GEOLOGY, GEOCHEMISTRY OF PHOSPHATIC ROCKS AROUND MARDEORA-HIRAPUR AREA IN CHHATARPUR AND SAGAR DISTRICTS, M. P.
X , ABSTRACT Ui \ M tPH j§i
THESIS SUBMITTED FOR THE DEGREE OF ©ottor of ^Ijilo^opJjp ^^ 3^^^,^ IN GEOLOGY
BY ZAFAR HUSAIN M. Sc, M. Phil., FGS <£ AMIG (Ind.) TA-S07
DEPARTMENT OF GEOLOGY FACULTY OF SCIENCE ALIGARH MUSLIM UNIVERSITY ALIGA R H 1 991 ABSTRACT
The early Proterozoic phosphorite occurrences of Hlrapur- Mardeora area/ districts Sagar and Chhatarpur (M.P.)« India* o£ Gangau Iron Formations of Bijawar Group are lying unconfor- mably over the basement of Bundelkhand Granite Complex of Archaean age, Mineralogically# the primary phosphorites being associated with shales. Ironstones and quartz-breccia are mainly composed of cellophane •> a carbonate fluorapatite phase, whereas the secondary phosphorites contain crandallite. The occurrences of cellophane and crandallite in the phosphorites indicated a contemporary phosphatization which was controlled by physical and chemical factors. The absence of organisms and carbonaceous matters revealed direct inorganic authigenic processes, which took place, during early Proterozoic age. The variations in the crystallinity of collophane and crandallite further supported the above observations.
The phosphorites bands and/layers suggested the supratidal to intertidal, continental margins and borderland of the Bijawar basin where phosphatization was completed. The subroundness of pellets indicated the low energy environment and poor transporta tion. The associations of hematite, goethite, limonite, iron- oxide and few grains of .magnetite as gangue constituents indicatec the highly oxidizing to slightly reducing environment followed by low grade metamorphism. -2-
The presence of primary and secondary sedimentary features supported the shallower, marine, restricted shoals of littoral basin of intracratonic sea which fringed the margins of the Bundelkhand Granitic Craton. The episodes of weathering in primary ores gave rise to secondary remobilised ore by diagenetlc processes in which crandallite was formed. The critical detailed study of the distributions and geo- chemical correlations among major constituents of the phosphorites, led the author to believe that most of the ores ^re in the primary state and deposited syngenetically with the host rocks through AUthiqenlc processes. The secondary ores, are mostly derived from the primary ores through eustatic sea-level changes, actions of sea-waves, tides, currents and groundwater circulations
It Is also suggested that the phosphatization might have taken place in a fairly oxidizing to reducing environments, tidal flats, continental margins, shallower parts of the Bijawar basin, tropical to arid climate, hight to moderate alkaline, marine, structural and stratigraphic controls, by upwelling currents and restricted circulation within the basinal waters. The formation of epigenetic secondary phosphorite was mainly due to lateriti- zation as indicated by the concentration trends of each element. There are innumerable cases of absorption and/adsorption and mutual ionic substitutions of certain major and minor elements attributed possible mild leaching of the syngenetic ores. The formation of crandallite in the .epigenetic ores may be due to ionic substitutions of Ca"^^ by Al'^"' Inside the apatite lattices. -3-
The distributions and inter-relationships of trace elements and trace with major oxides and their ratios in primary and secondary phosphorites revealed that these elements were also precipitated by direct, inorganic, syngenetic and authigenic processes in the primary ores and by epigenetic leaching, remobillzatlon and reprecipitation in the cavities, voids, fractures, fissures and vein fillings in the secondary ores during diagenetic processes. It may also be possible that some parts of the trace metals might have been adsorbed/absorbed in the groundmass and partly replaced within the apatite.
The Hirapur-phosphorites are classified in various groups as - sedimentaryi authigenic, orthochemlcal, allochemical and metachemical; nonaltered and altered; acid, furnance and benifi- ciation grades; ancient phosphorites; high alkaline and moderate alkaline; phosphatic silicanite and phosphatic dolomitic- limestone groups, etc.
The plots of individual weight percentages and ratios of major constituents revealed that the main source of the Hirapur phosphorites is adjoining Bundelkhand'Complex, which is the basement of the Bljawar basin. Besides, the other sources it may be the host rocks of Bljawar Group, local active ancient rivers and their major tributaries and to some extent sea- basinal waters. GEOLOGY, GEOCHEMISTRY OF PHOSPHATIC ROCKS AROUND MARDEORA-HIRAPUR AREA IN CHHATARPUR AND SAGAR DISTRICTS, M. P.
THESIS SUBMITTED FOR THE DEGREE OF Bottor of S^W^flophv IN GEOLOGY
BY ZAFAR HUSAIN At. Se., M. PMf., FGS4AMIG (Ind.)
DEPARTMENT OF GEOLOGY FACULTY OF SCIENCE ALIGARH MUSLIM UNIVERSITY ALIGARH 1991 DEPARTMENT OF GEOLOGY ALIGARH MUSLIlVi UK'IVERSiTV Dr. S~.;ad h. F.sjn 1ST3.1 i ALIGARH—202002 (IT^^DIA) \- 3c , Ph.D., D.Sc P-on. (Oo/I ) r 3 C 1 3 /A.S (h - - ; 'r(C'iaj PPOFES£0=^ Re'. No. Dated :i^.-..7.'.LJli
The thesis entitled, "Geology, Geochemistry of
phosphatic rocks around Mardeora-Hirpur area in
Chhatarpur and Sagar districts, M.P." is being submitted
for the award of Doctor of Philosophy at the Aligarh
Muslim University, Aligarh, by Mr. Zafar Husain, is his
original contribution and is an addition to the existing
knowledge on the subject.
The work has been carried out under my
supervision and has not been published or submitted for
any degree of this or any other University. He is,
therefore, allowed to submit the thesis for the award of
Ph.D. degree of this University. T4507
'iff Ace No. "^^
29 JUL W4
CHEC P-20oa
^-.-r-r ^ Ar»<: "'"^ ^5!^ ACKNOWLEDGEMENT
I am highly grateful to my supervisor, Professor S.H. Israili,
Ph.D., D.Sc, Chairman, Department of Geology, Aligarh Muslim
University, Aligarh, for his excellent guidance and estimable supervision in my present research from the beginning to a successful completion of work.
I am also highly thankful to Prof. S.H. Rasul (Ex-Chairman)
Department of Geology, A.M.U. and Prof. S.N. Bhalla, for their genial encouragement in course of my present investigations. I am aslo thankful to fTIJ\: A.V. Phadke (Ex-Director). Department of Atomic
Energy, Hytfeiqabad (A.P.) for granting me official permission to undertake present research in the Hirapur-Mardeora area, districts
Sagar and Chhatarpur (M.P.).
I am also thankful to Mr. A.S. Siddiqui, Deputy General
Manager, Indian Rare Earths Ltd. Chhatrapur (Orissa) and Dr. V.D. Rao,
Scientist, N.G.R.I., Hyderabad (A.P.) for providing the laboratory facilities to carry out chemical analysis of the rock samples; to
Dr. K.B. Rao, SO/SF and Mr. S.Q. Hoda, SO/SF for helping me to consult literature freely in the Central Library of my office in
Hyderabad; to Dr. M.W.Y. Khan for XRD analysis of phosphorite samples; to Dr. H.M. Khan, SO/SD for rechecking thin sections of rocks.
Thanks are also due to Messrs. L.D. Upadhyay, SO/SF and
R.M. Sinha, SO/SF for forwarding my leave application and to A.K. Das,
SO/SG and K.K. Sinha, SO/SG for sanctioning me leave for completion -11-
and submission of my thesis- To Messrs'- S.N. Singh, SO/SG;
D.V. Katre, SO/SF; E.U. Khan, SO/SF; A.K. Rai, SO/SE; S.K. Das,
SO/SE; R.G. Mohanty, SO/SE, M.B. Verma, SO/SE; P.K. Sinha, SO/SE;
S. Fahmi, SO/SE; Dr. Shiv Kumar, SO/SE; A.A. Qidwai, SO/SD;
S.J. Chavan, SO/SD and I:H; Israili, SO/SD; thankful for their valuable suggestions from time to time. Thanks are also due to
Drs. L.A.K. Rao, and S. Khursheed, Readers, Department of Geology and Dr. Hafiz Mohd. Ilyas Khan, Pool Officer, Psychology
Department and Mr. N.A. Khan, Co-brother-in-law,
Officer-in-Charge, University Telegraph Office, Aligarh, for their moral supports and encouragement during my stay at Aligarh.
Many thanks also due to Messrs Kr. Farahim Khan,
A.A. Khan and Mohd. Arif and Nurul Hasan, Research Scholars for assisting me in many ways to get the type-script of the thesis ready for submission; to S.H. Faridi for providing me accommodation facility at Aligarh; to (Late) Iqbal Ahmad for the preparation of thin sections; to Saleemuddin Ahmad and G. Martin for cortographic work; to Iqbal Khan for photography; to B. Nath for printing electrostat copies of the thesis; to S.M. Hasan for typing the manuscript and to Mohd. Akhtar for binding the thesis.
Last but not least, I acknowledge with pleasure for the assistance, I received from my wife, Mrs. Shahnaz Begum for the great pains she took to manage well my domestic affairs all throughout my engagement in research and without her help, I could not have successfully completed my research peacefully.
{ ZRFAB/RUS}''-h&Y' Scientific Officer/SD Department of Atomic Enerav CONTENTS
CHAPTER-I INTRODUCTION
1.1. Rock Phosphates Today 1 1.2. Location and Accessibility 3 1.3. Indian Phosphate Deposits 3 1.4. Important Phosphate Deposits of 5 the world 1.5. Climate and Rainfall 7 1.6. Flora and Fauna 7 1.7.,Topbgraphic Features 8 1.8. Drainage 9 1.9. Previous Work 9 9.1 The Bundelkhand Complex 10 9.2 The Bijawar Group 13
CHAPTER-II METHODS & TECHNIQUES OF WORK 18
11.1. Field Investigations 18 11.2, Laboratory Investigations 20 2.1. Petrological Investigations 20 2.2. Geochemical Investigations 20 2.2.1. Crushing and poweiering 20 of samples 2.2.2. Procedure adopted for 21 geochemical analyses
CHAPTER-III LITHOSTRATIGRAPHY & STRUCTURAL CONTROL 24 OF PHOSPHORITES
III.l. Generalised Geological Sequence 24 of Bijawar Basin -ii-
III.2. Geological Sequence of the Study ... 26 Area 2.1. Bundelkhand Complex .... 28 2.1.1. Granites ... 30 2.1.2. Granitic Gneisses ... 31 2.1.3. Schists ... 31 2.2. The Bijawar G-roup ... 32 2.2.1. Quartzites ... 40 2.2.2. Limestones ... 40 2.2.3. Shales ... 40 2.2.4. Ironstones ... 45 2.2.5. Quartz-Breccia or ... 48 Hornstone-Breccia 2.2.6. Shale-phosphorites ... 53 2.2.'7. Secondary Phosphorites ... 59 2.2.8. Ironstone-Phosphorites ... 60 2.2.9. Quartz-Breccia ... 61 Phosphorites
CHAPTER-IV PETROLOGY, PETROGRAPHY & PETRO-MINERALCX3Y ... 64
IV.1. Bijawar Group (Early to Middle ... 75 Precambrian) 1.1. Megascopic and Microscopic ... 75 Studies 1.1.1. Quartzites ... 1.1.2. Limestones 1.1.3. Dolomitic Limestones 1.1.4. Quartzitic Limestones 1.1.5. Quartzitic Shales 1.1.6. Shales 1.1.7. Ironstones and Iron- Ores -iii-
1.1.8. Quartz-Breccia ... 84 1.1.9. Shale Phosphorites ... 85 1.1.10. Secondary Phosphorites,». 87 1.1.11. Ironstone Phosphorites... 88 1.1.12. Quartz-Breccia ... 89 Pnosphorites 1.2. Scanning Electron Microscopic ... 90 (SEM) Study of Phosphorites 1.2.1. Shale Phosphorites ... 90 1.2o2. Secondary Phosphorites ... 91 1.2.3. Ironstone Phosphorites .... 93 1.2.4. Quartz-Breccia Phos- ... 94 phorites 1.3. X-Ray Diffraction (XRD) Study ... 95 of Phosphorites.
CHAPTER-V DISTRIBUTION OF MAJOR IONS & THEIR 106 CORRELATION
V.l. General Statement 106 V,2. Distribution of Major Ions 108 2.1. Phosphorus Pentaoxid^ ^^2^5^ 109 2.2. Lime (CaO) 123 2.3. Carbondioxide (COj) 126 2.4. Hydrogen Peroxide (HjO"*") 133 2.5. Alumina (AI2O,) 135 2.6. Ferric Oxide (Pe202) 141 2.7. Ferrous Oxide (FeO) 149 2.8. Silica (Si02) 151 2.9. Soda (Na20) 156 2.10.Potash (K2O) 160 2.11.Magnesia (MgO) 163 2.12.Titania (Ti02) 166 2.13.Manganse-0xide (MnO) 170 -IV-
V,3. Geochemical Relationship between 173 Major elements 3.1. Relationships of P2°5 with 174 various oxides 3.1.1 P2O5 vs, CaO 174 3.1 ,2 P2O5 vs, CO 2 179 3.1 .3 P2O5 vs, AI2O3 185 187 3.1 ,4 P2°5 ^^ 189 3.1 ,5 P2°5 ^^ Na2 0 3.1.6 P2O5 vs, 192 3.1.7 P2O5 vs 192 ^^2°3 3.1.8 P2O5 vs FeO 196 197 3.1.9 P2°5 ^^ SiO^ S.l.lO.P^O^ VG MnO 200 3.1.11.P20^ vs MgO 2 02 3.1.12.P20^ vs. TiO^ 205 3.2 Inter-relationships between 207 various oxides 3.2.1. CaO vs. CO2 207 3.2.2 . CaO vs. H20'^ 208 3.2.3. CaO vs. SiO- 208 3.2.4, CaO vs. MnO 210 3.2.5. CaO vs. Fe-O- 210 3.2.6, CaO vs. FeO 212 3.2.7, CaO vs. Na20 212 3.2.8 CaO vs. K2O 215 3.2.9. CaO vs. AI2O3 216 3.2.10.CaO vs. MgO 218 3.2.11.Fe203 vs. HjO"*" 221 3.2.12.Fe203 vs. COj 221 3.2 .13.Fe202 vs. AI2O3 222 3.2.14.Fe203 vs. Ti02 224 3.2.15.Fe203 vs. FeO 224 -V-
3.2.16.Fe202 vs. MnO 227 3, 17. FeO vs. MgO 229 3. 18. FeO vs. Mn.O 231 3, FeO vs. TiO 231 19 2 3, 20 AI2O3 vs Ti02 232 3, 21 SiO, vs, AI2O3 232 3 ,22 SiO. vs, Ti02 234 3 ,23 SiO, vs, Na20 2 34 3 ,24 SiO, vs K2O 236 3 ,25 SiO, vs Fe203 236 3 , 26 SiO, vs, FeO 238 3 27, Na2 0 vs K2O 240 3 28 Na20 vs, AI2O3 240 3 29, NajO vs, CO, 241 3 2.30, ^32^ vs 243 3 2.31. NajO vs ^^2^3 245 3 2.32, NanO vs , FeO 247 3 2.33, K2O vs. ^^2^3 247 3 2.34, K2O vs. FeO 248 3 2.35, K-O vs. AloO 2^3 248 3 2.36 K2O vs. MgO 250 3 2 37, Ratio Ca0/P20^ vs. ^2^5 251 3 ,2 38, Ratio Na2 0/P2 0c vs. 254
3.2.39 Ratio CO2/P2O5 vs. PjOc 256 3.2.40. CaO/MgO/vs. P„0^ 257
CHAPTER-VI TRACE METAL DISTRIBUTION & THEIR 261 CORRELATIONS
VI.1. General Statement 261 VI.2. Trace Metal Distributions 273 2.1. Uranium Oxide (U^O.) 273 2.2. Vanadium (V) 275 2.3. Nickel (Ni) 276 2.A. Chromium (Cr) 278 -vi-
2.5. Copper (Cu) ... 280 2.6. Cobalt (Co) ... 281 2.7. Zinc (Zn) ... 281 2.8. Cadmium (Cd) ... 283 2.9. Gallium (Ga) ... 285 2.10.Lead (Pb) ... 285 VI.3. Trace Metal Correlations ... 287 3.1. vs . 287 U3°8 Ni 3.2. vs. V 289 ^3^8 3.3. VS . Cr 289 U3°8 3.4. vs . Cu 290 "3°8 •3 • ^ • vs. Pb 290 "3°8 3.6. V vs. Cr 292 3.7. V vs. Ni 295 3.8. V vs. CO 295 3.9. Ni VS; . Or 295 3.10 . Ni VEi . Cu 297 3.11 . Ni VSi . Co 297 3.12 .Ni V£i . Cd 297 3.13 . Cd V£! . CO 299 3.14 . Cd V£; . CiJ 299
3.15 .Co V£> • 0 jc 301 VI.4. Trace and Major Ions Correlation's ... 301 4.1. vs. P2°5 ^3^8 302 4.2. P2O5 vs. Ni 304 4.3. ^2^5 vs. Pb 306 4.4. vs. P2°5 Cr 306 4.5. vs. Cd ^2^5 308 4.6. vs. Co ^2^5 310 4.7. vs. Cu ^2^ 310 4.8. vs. V ^2^5 312 4.9. P2O3 vs. Zn 312 4.10 .CaO vs. 312 "3^8 -vii-
4.11. CaO vs. V ... 314 4.12. CaO vs. Pb ... 314 4.13. CaO vs. Ni ... 316 4.14. CaO vs. Cu ... 316 4.15. CaO vs. Cd ... 318 4.16. CaO vs. Co ... 318 4.17. CaO vs. Cr ... 318 4.18. AI2O3 vs. Co ... 320 4.19. AI2O3 vs. UjOg ... 320 4.20. MnO vs. ^2^8 "' ^^^ 4.21. CO2 vs. U^Og ... 323 4.22. H20"'" vs. U3OQ .... 324 4.23. Fe203 vs. U^Og ... 324 4.24. Pe20^ vs. Cr ... 327 4.25. Fe2°3 ^^* ^° *** ^^^ 4.26. Fe2^3 ^^* ^^ '" ^^^ 4.27. NajO vs. 030^ ... 329 4.28. KjO vs. U30g ... 329 4.29. Si02 vs. UjOg ... 331 4.30. SIO2 vs. Cr ... 331 4.31. Si02 ^^* ^ ••* ^^"^ 4.32. Si02 vs. Ni ... 333 4.33. MgO vs. Ni ... 335 4.34. MgO vs. Cr ... 335 4.35. Ratio U3O /P 0 vs. ^2^5 "' ^'^'^
4.36. Ratio ^-^^Q/^^O^S ^^' ^^2*^3 "* ^"^^ 4.37. Ratio U30g/Fe203 vs. ^2^5^ "' -^^^ ^«2°3 4.38. Ratitatio V/PV/P^O2 0^ vs. P^OP2O^5 ... 340 4.39. Ratio Cu/P20^ vs. P2O5 340 4.40. Ratio Cr/Al203 vs. ^120^ ... 342 -vll^-
CHAPTER-VII CLASSIFICATION OF PHOSPHATIC SEDIMENTS 344
VII.1. General Statement 344 VII.2. Classification of Phosphatic 345 Sediments of the Study area
CHAPTER-VIII PROVENANCE OF PHOSPHATIC SEDIMENTS 356
VIII.1. General Statement 356 VIII.2. Sources of Phosphorus 357
CHAPTER-IX GENESIS OF PHOSPHATIC SEDIMENTS 374
IX.1. General Statement 374 IX.2. Genesis based on Petrology, Petro- 379 mineralogy and Petrography IX.3. Genesis based on major Elements 401 Geochemistry IX.4. Genesis based on Trace Elements 414 Geochemistry IX.5. Genesis based on Major and Trace 418 Elements Geochemistry
CHAPTER-X SUMMARY & CONCLUSIONS 422
LITERATURE CITED 429 LIST OF FIGURES
Flgure-1 An outline map of Indla^ showing the location 2 of Hlrapur-Mardeora area, Sagar and Chhatarpur districts.
Flgure-2 Precambrian phosphorite occurrences in India. 4 Figure-3 Phosphorite occurrences in the world. 6 Figure-4 Diagramatic cross-section along the line A-B 19 across the phosphorite deposits, Hlrapur- Mardeora area/ districts Sagar and Chhattarpur (M.P.). Figure-5 A typical X-Ray Diffractogram is showing the 97 occurrences of carbonate-fluorapatite (cellophane) and quartz in silt sized fractions of primary phosphorites of Hlrapur-Mardeora area. Figure-6 A typical X-ray Dlffractogram is showing the 99 occurrences of carbonate-fluorapatite (cellophane) and gangue minerals (quartz, muscovite, goethite, etc.) in clay fractions of phosphorites of Hlrapur-Mardeora area. Figure-7 A typical X-Ray Diffractorgram is showing the 102 occurrences of carbonate-fluorapatite (crandallite) and quartz in silt sized fraction of secondary phosphorite of Hlrapur-Mardeora area. -11-
Figure-8 Distribution of P^^s 119 Figure-9 •• CaO 124
Figure-10 '• CO2 131
Figure-11 " II H2O+ 134
Figure-12 " AI2O3 139
Figure-13 •• 148
Figure-14 " FeO 150
Figure-15 " Si02 155
Figure-16 " Na20 158
Figure-17 162
Figure-18 " •• u MgO 165
Figure-19 " Ti02 168
Figure-20 " MnO 122
Figure-21 Relationship between ^2^5 VS. CaO 178
Figure-2 2 •• w « vs. CO2 178
Flgure-23 M M « vs. AI2O3 186
Figure-24 •• " •• vs. H2O+ 186
Figure-2 5 •• '• •* vs. NagO 190
Figure-26 " " " vs. K2O 190
Figure-2 7 " " •• vs. ^«2°3 195 Flgure-28 " H vs. Feb 195
Figure-2 9 •' vs. SiOj 199 Figure-30 " vs. MnO 199
Figure-31 " vs. MgO 204
Figure-32 " II vs. TiO- '204 -iii-
Flgure-33 ReXationship between CaO vs. CO, 206
Flgure.34 vs. HoO"* 206
Figure-35 vs. SiO, 209
Figure-36 vs.- MnO 209
Figure-37 vs. Fe2 03 211
Figure-38 vs. FeO 211
Figure-39 " vs. NajO 214 Figure-40 " vs. K^O 214
Figure-41 " vs. AI2O3 217
Figure-42 " vs. MgO 217
Figure-43 ^®2°3 ^«- "2°'' 220 Figure-44 " vs. COo 220
Figure-45 " vs. AI2O3 223
Figure-46 •• vs. Ti02 223
Figure-47 " vs. FeO 225
Figure-48 •* vs. MnO 225
Figure-49 FeO vs. MgO 228
Figure-50 '• vs. MnO 228
Figure-51 " vs. Ti02 230
Figure-52 AI2O3 vs. Ti02 230
Figure-53 Si02 vs. A1203 233 Figure-54 vs. Ti02 233
Figure-55 vs. Na2 0 235
Figure-56 vs. KjO 235
Figure-57 vs. Fe203 237
Figure-58 vs. FeO 237 -iv-
Pigure-59 Relationship between NSjO vs. KjO ... 2 39
Pigure-60 " " " vs. AI2O3 ... 239 Pigure-6l " " "vs. COj ••• 242 Figure-62 " " " vs. HjO ... 242 Figure-63 " " " vs. PSjO^ ... 244 Figure-64 " " " vs. FeO ... 244 Figure-65 " " KjO vs. ^6203 ... 246 Figure-66 " " " vs. FeO ... 246 Figure-67 " " " vs. AljOj ... 249 Pigure-68 ' " " " vs. MgO ... 249 Figure-69 Relationship between ratios CaO/PjO^ vs. P2O5 252 Figure^70 " " " NajO/PjOg vs. P^^S ^52 Figure-71 " " " COj/PjOg vs. P2O5 255 Figure-72 " " " CaO/MgO vs. P2O5 255 Pigure-73 Distribution of UjOg and V ... 274 Figure-74 " " Ni and Cr ... 277 Figure-75 " " Cu and Co ... 279 Pigure-76 " " Zn and Cd ... 282 Figure-77 '* " Ga and Pb ... 284 Pigure-78 Relationship between U^Og vs. Ni ... 286 Figure-79 " " '• vs. V ... 286 Figure-80 " " " vs. Cr ... 288 Figure-81 " " " vs. Cu ... 288 Figure-82 " " " vs. Pb ... 291 -V-
Figure-83 Relationship between VV vs. Cr 291 Figure-84 " '• n vs. Ni 293 Pigure-85 " n vs. Co 293 Figure-86 " Ni vs. Cr 294 Figure-87 " •1 vs. Cu 294 Figure-88 " •• •t vs. Co 296 Figure-89 " " H vs. Cd 296 Pigure-90 " " Cd vs. Co 298 Figure-91 " '• •• vs. Cu 298 Pigure-92 Co vs. Cr 300 303 Figure-93 " " ^2^5 vs. ^3°8 Figure-94 " " II vs. Ni 303 Figure-95 " " 11 vs. Pb 305 Figure-96 " " II vs. Cr 305 Figure-97 " " II vs. Cd 307 Figure-98 " " II vs. Co 307 Figure-99 " " •• vs. Cu 309 Figure-100 " " II vs. V 309 Figure-101 •• » II vs. Zn 311 CaO Pigure-102 " •• vs. "3^8 311 Figure-103 » II vs. V 313 Figure-104 " " II vs. Pb 313 Figure-105 '• " II vs. Ni 315 Pigure-106 . '" II vs. Cu 315 Figure-107 •• " II vs. Cd 317 Figure-108 '• '• II vs. Co 317 Figure-109 •' " II vs. Cr 319 -vi-
Pigure-110 Relationship between AljOo vs. Co 319 Plgure-111 " ^^. U3OQ 321 Plgure-112 MnO vs. U^Og 321 Pigure-113 CO2 vs. U3OQ 322 Pigure-114 H2O+ vs. U3OQ 322 Figure-115 ^«2°3 ^^- "3°8 325 Pigure-116 " vs. Cr 325 Figure-117 " vs. Co 326 Pigure-118 " vs. Ni 326 Pigure-119 Na20 vs. UgOg 328 Figure-12 0 K2O vs. U3OQ 328 Pigure-121 Si02 vs. U3 0g 330 Figure-122 vs. Cr 330 Pigure-123 " vs. V 332 Plgure-124 vs. Ni 332 Pigure-125 MgO vs. Ni 334 Flgure-126 " vs. Cr 334 Pigure-127 Ratio U30g/P205 vs. P20g 336 Figure-.128 " U3V^«2°3 ^^- ^^2°3 336 Pigure-129 " "3V^^2°3 ^^- P2°5 339 Pigure-130 " V/PjOg vs. P2O5 339 Pigure-131 " Cu/P20g vs. PgOc 341 Pigure-132 " Cr/Al2 03 vs. AI2O3 341 -vii-
Pigure-133 Petrochemical classification of phosphorites 353 based on weight percentages of Si02 - CaO + MgO.
Pigure-134 Relationship between Ti02 vs. Total iron/MgO. 364 Pigure-135 Triangular plot showing relations of TiOj - 365 K2O - P2O5. Figure-136 Triangular plot showing relationship of Ti02 - 367 MnO - P2O5. Pigure-137 Triangular plot showing relationship of 369 AI2O3 - Total Fe203 - Si02
Pigure-138 Triangular plot showing relationship of 370 Si02 - AI2O3 - K2O. Pigure-139 Triangular plot showing relationship of 372 CaO - Fe203 - M^O^.
In Pocket Geological and Sample Location map of Hirapur- Mardeora area* Districts Sagar and Chhatarpur (M.P.), India. LIST OF TABLES
Table-I Showing the location of important villages/ 485 towns in the study area. Table-II Major elements distribution in phosphate 486 bearing rocks of Bijawar Group around Hirapur- Mardeora area. Table-III Major elements distribution in various litho- 489 logical units of Bundelkhand Complex, Bijawar and Semri Groups around Hirapur-Mardeora area. Table-III A Major elements variations in phosphate bearing 494 rocks of Bijawar Group around Hirapur-Mardeora area. Table-IV Trace elements distribution in phosphate bearing 496 rocks of Bijawar Group around Hirapur-Mardeora area. Table-V Trace elements distribution in various lithologi- 499 cal units of Bundelkhand Complex, host rocks of Bijawar and Semri Groups around Hirapur-Mardeora area. Table-VA Trace elements variations in phosphate bearing 502 rocks of Bijawar Group around Hirapur-Mardeora area. Table-VI Generalized Geological set of the Bijawar Basin 24 (after Krishnan, 1949 and Dubey, 1952).
Table-VII Generalized Geological set of the Bijawar Basin 25 (after Rajarajan, 1978). -ii-
Table-VIII Generalized Geological set of the Bljnwar Basin 26 (after Mathur and Mani, 1978). Table-IX The stratigraphic succession of the study area 27 (after Banerjee, et al., 1982). Table-X Showing the details of phosphate bearing minerals. 503 Table-XI Recalculated ratios of major elements of phos- 512 phorites of Bijawar Group of study area. Table-XII Recalculated ratios of major and trace elements 514 of phosphorites of Bijawar Group of study area. Table-XIII Recalculated weight percentages of major elements 515
of phosphorites of Bijawar Group of study area. Table-XIV Recalculated weight percentages of major elements 516 of phosphorites of Bijawr Group of study area. Table-XV Recalculated weight percentages of major elements 517 of phosphorites of Bijawar Group of study area. Table-XVI Recalculated weight percentages of major elements 518 of phosphorites of Bijawar Group of study area. LIST OF PLATES
Plate-I Photomicrograph A I Shale Phosphorites 520 Plate-I Photomicrograph B t Shale Phosphorites 520 Plate-li Photomicrograph C ! Sfecondary Phosphorites 522 Plate-Ii Photomicrograph D : Secondary Phosphorites 522 Plate-III Photomicrograph E ; Ironstone Phosphorites 524 Plate-III Photomicrograph F : Ironstone Phosphorites 524 Plate-iv Photomicrograph G 1 Ironstone Phosphorites 526 Plate-iv Photomicrograph H : Ironstone Phosphorites 526 Plate-v Photomicrograph I : Quartz-Breccia Phosphorites 528 Plate-V Photomicrograph J t Quartz-Breccia Phosphorites 528 I
CHAPTER - I INTRODUCTION
I.l. ROCK PHOSPHATES TODAY :
Rock phosphates today are regarded as one of the most important economic minerals used by man, nearly 90% of the total world phosphate output is utilized for the manufacture of a number of fertilizers like, superphosphate, triple-super phosphate, diamnionium-phosphate and monoammonium phosphate, which are essential for agro-industries all over the globe. Agricultural resources, followed closely and now intimately by energy, are the most basic of all the resources available to man. Phosphates are also very promising potential source of not only a number of trace elements and by-products but also used for the manufacture of phosphoric acid, detergents, water softening agents, pharmaceuticals, metal protection and gasoline additives (Leibig, 1830; Krishnan, 1942; Freeman, 1977; Riggs, 1979; Bentor, 1980; Sheldon, 1981 and 1982; Notholt and Hartley, 1983; Cook and Shergold, 1983; Sinha, 1984; Shangquing, 1984; Banerjee, 1985; Cook, 1987 and Radha- krishna, 1937). 2 3
1.2. LOCATION AND ACCESSIBILITY :
The Proterozoic phosphorites of Hirapur-Mardeora areas, districts Sagar and Chhatarpur, Madhya Pradesh, lies between latitudes; 24°19'0" N and 24°23«0" N and longitudes; 79°9«0" E and 79°14'0" E (Survey of India, Toposheet No. 54 P/3), Mardeora village is situated at about 76 kms, north of Sagar district Headquarters of Sagar-Chhatarpur road and falls in the Chhatar- pur district of Madhya Pradesh. Hirapur village is situated at about 6 kms, further north of Mardeora village on the sane road and falls in the Sagar district of Madhya Pradesh (Figure-1). The latitudes, longitudes and geographic locations of the villages/towns namely, Bijawar, Hirapur, Mardeora, Hatkoi, Agra, Chauki, Tighora, Amarmao and Bassia are given in Table-I.
1.3. INDIAN PHOSPHATE DEPOSITS :
During the last decade, India achieved a major break through in the identification of large resources of sedimentary phosphorites based on the geological concepts. The discovery of phosphate deposits in association with stromatolitic structures in the Precambrian rocks around Udaipur at Jhamarkotra* Matoon, Kanpur and other localities in Rajasthan; Cuddapah in Andhra Pradesh; Hirapur-Mardeora and Jhabua in Madhya Pradesh; Pithora- garh and Lalitpur in Uttar Pradesh, is no doubt the most out- 4
U Ul
<< Q ^ Q P lu in U) 1o " K |0 a C£> O of £ aul \^ O m 3- < 3 1 ?^1 o a Hi 5 f? UJ 1 3 > D 2in C>sc>j 0 W M n (X (0 tu u o 10*" o < < > > O K OL t- a Ul 3 C UJ O < U 5 < a Q 2 g I a (D !3 S a: (t o in u o ai u U^ »— — ex. a: u) o t CL <: c/) ^ o X a. < w Ul a: V- tJ V if « *2 C c CD c JO 1° h < p •* ^ O U) U «
standing attainments of the systematics of prospecting and exploration. Other important promising phosphate deposits of India occur in the Hazaribagh and Singhbhum districts of Bihar; Purulia in West Bengal; Jammu and Kashmir state; Chamba/ Mandi, Bilaspur, Mahasu and Sirmur in Himachal Pradesh; Paritibba/ Garhwal* Nainital, Mussoorie and the Vindhyan tract in Uttar Pradesh; Jaisaimer and possibly in some parts of jodhpur in Rajasthan; Khammam# Warangal# Karimnagar, Adilabad, Kasipatnam, Mehboobnagar, Kumool in Andhra Pradesh; Trichirapalli, S. Arcot in Tamil Nadu state; and Pondicherry; Laccadive Islands (Dar, 1970; Kapur, 1980; and Lodha, et al., 1984).
Total probable reserves of rock-phosphate in our country have been estimated at —^145 million tonnes of which 20 million tonnes are directly usable in the fertilizer industry (Lodha, et al., 1984). Estimated reserves and grade of the Precambrian phosphorite occurrences of Hirapur area are 1.44 million tonnes with an average, grade of 17.33% (Srivastava and Banerjee, 1981) (Figure-2).
1.4. IMPORTANT PHOSPHATE DEPOSITS OF THE WORLD :
Among the important occurrences of the world phosphorite deposits mentioned, mention may be made of U.S.A./ Mexico, U.S.S.R. and Morocco. Other important deposits are known from Africa, Middle East, China, Ocean Islands, Vietnam, Australia, 6
en
°o_ Q cr <: o X 00 uJ CL
Q:
Qc:<
"O LU X
00-
CO LU o (O ul t- LJ lO oc Ul "o Q: o X CM X UJ ID -i '^ ain O o aS X o o a u o > (T (/} < o CD- UJ 111 Z 7 CO 1-1 ul a. cc o LJ > o Ul 2 -1 o CL iij Z 2 < ">o tn tr ^ < -^ < _l O o S < (£> X • X a CL « • —• evi ro I "O-
•o 7
Peru, Finland/ Canada, Brazil, Senegal, Israel, Jordan, Iraq, Turkey, Saudi Arabia, Sri Lanka, Siberia and Scandinavia (Howard, 1979) (Figure-3).
1.5. CLIMATE AND RAINFALL t
The climate of Hirapur-Mardeora area of Banda Tehsil, Sagar and Chhatarpur districts, M.P, is generally pleasant and salubrious. The temperature of the area is very moderate. An observatory was established in 1870 at an elevation of 1769 feet and was later removed to another at an elevation of 1807 feet in 1896. The average monthly minimum and maximum temperatures are 52°F and 77°P in January, 78.5°F and 105°F in May and 74°F and 83.5°F in July and the lowest, 39.1*^P recorded on 9th February, 1893. Slight frosts occur during the cold weather and cause which damage the crops on low lying land near the rivers. The annual rainfall has been varying from 101 to 140 cms, (Dubey, 1952 and Rajarajan, 1978).
1.6. FLORA AND FAUNA :
The study area, which is thickly forested, has been divided into Hirapur Reserve Forest in the South and Tighora and Amarmao Reserve Forests in the North and South-west (Figujre - in pocket) . These forests are of the mixed types (Dubey, 1952) . The important and common vegetations in this ares are teak samplings (Tectonia grondis), Saj (Terminilia tomentosa)/ Dhaura (Anogrinus latifolia)* Koha (Terminalia arjuna)# tendu or ebony (Diospyroz tomentosa), Kullu (Strenlia ureus) and Sejo or Lendia (Lager stroemia pariflora). The forest of the Banda Tehsil are infested with tigers and bears, though the animals are occasionally seen in the Reserve Forests of other parts of the district. Leopards are usually seen in scrubby jungles and they occasionally stray into plain country. The tigers are seldom found in the jungles infested with wild dogs. The hyena# fox and wild cats are other carnivours which inhibit these forests. Among the herbivorous animals, nilgai, sambar, spotted deer, bears, porcupines and rarely wild goats, could be seen in the jungles. The reptiles are also common in this area (Rajarajan, 1978).
1.7. TOPOGRAPHIC FEATURES :
As far as the scenary is concerned this area provides a pleasant spot. Mostly the region is hilly rising upto ^iSS. The hills are usually clothed with vegetation. The tropical weathering of Bundelkhand Complex on the western parts of the region rugged dome shaped, large boulders which are often found resting on the hills. The soil is brownish in colour 9
having coarse grains of quartz dispersed throughout. The eastern part is low lying* made up usually of limestone, which, on weathering, and erosion gave rise to a topography, which is characterized by the presence of elephant skin structures and Karst. There are scane pockets of iron-ores that form beautiful red hills and the soil near about is vermi- llian red in colour (Dueby, 1952).
1.8, DRAINAGE i
Though the topography is rugged in this area, it is farily good for the drainage. The oldest river of the area, known as the Kauthan, flows through Semarkhera, Chauki, Hinota, Kachhar and sagoria from south-east of Hirapur, but it is a 4 seasonal river which is generally full of water during rainy season. There are several gullies and nalla-cuttings by rapid streams (major nala of the Bila River which passes near Amarmao village) and water courses are active only during the rainy season (Dubey, 1952 and Rajarajan, 1978) (Figure - in pocket).
1.9. PREVIOUS WORK s
The author presents hereunder = brief summary of the geological contributions of the previcus workers on the 10
Bundelkhand Complex and the Bijawar Group occurring in the study area.
1.9.1. The Bundelkhand Complex s
The attention of the Geological Survey was first directed to the Central India in 1854. Medlicott (1859) was the pioneer worker who identified and reported the occurrences of 'Bundelkhand Complex*. Later on, Medlicott (1860, 1862, 1867, 1868 and 1869) and Medlicott and Blanford (1879-87) studied in some detail the geology. Mallet (1872) introduced the term 'Bundelkhand Gneiss*. Geological formations of the Sagar and Damoh districts were first surveyed and mapped (scale !•• » 1 mile) by W.L. Willson, a geologist of the Geological Survey of India, during the year 1868 to 1876, under the stewardship of sir Thomas Oldham, the first Director of the Geological Survey of India. During this survey Willson (1874) noted that the trap dykes traversing the Bundelkhand country were in some cases younger than the quartz-reefs although they never penetrated either the Bijawars or the Vindhyans. He however, did not publish his work and the old geological map prepared by him is also untraceable. Heron (1936) had also written a brief account of 'Bundelkhand Gneissic Complex'. it
Many other geologists of Geological Survey of India namely, Chatterjee (1941-42); Mehta (1944-45); Krishnaswamy (1945-46); Roychowdhury (1947-48; 1950-51 and 1955-56); Sri- vastava (1951-52) tried to map the Central part of India in an attempt to search for some economic minerals. The later work done by Rochowdhury of the Geological Survey of India was published by the G.S.I, in 1955 and under the title as 'Economic Geology and Mineral Resources of Madhya Bharat*. Rajarajan (1951-52 to 1961-62) carried out systematic geolo gical mapping of Sagar and Daraoh districts (M.P.), covering a total area of about 15884.40 sq. kms. on the R.F. Scale 1 s 63,360. The work, done by Rajarajan continued for iO field seasons published by the G.S.I, in 1978 under the title, 'Geology of Sagar and Wfestem part of Damoh districts (M.P.)*, Krishnan (1948, 1949, I960 and 1968) has written a detailed account on •The Bundelkhand Gneisses and its equivalents in India* belong to Archean age, Pascoe (1950,' 1955 and 1965) studied the meta- morphism of the granites and later intrusives in the Bundelkhand regions.
Misra, et al. (1952); Chiplonkar (1952) and his M.Sc. students of Saugar University, Sagar (M.P.) and Chibber (1952) of Banaras Hindu University, Varanasi (U.P.), have also described the petrology of granites of Bundelkhand area. Mathur (1954 and 1955) has published notes on 'The Granitization of quairtzites and Zircon in granite of Bundelkhand area*. 12
Misra (1948) studied the Hybrid-Gneisses and Misra and Saxena (1955), variations in Bundelkhand Gneisses etc. Later on Misra and Saxena (1956) identified some xenoliths and other older rocks of Bundelkhand Granites. Saxena (1953, 1956, 1957, 1961, and 196IJ.) has published papers on *Agmatites* in Bundel khand Granites and associated Gneisses and the phenomenon of •Granitization'; trend of variations in *heavy minerals* percentages during the course of granitizations, structural study of the Bundelkhand Granites and their associated rocks; the Bundelkhand Granites and associated rocks and 'inclusions' and 'raetamorphism' in Bundelkhand Granites.
Jhingran (1953-54) who studied the Bundelkhand Granites and Gneisses of this region has published a few p^ers. Misra and Sharma (1974) studied the 'Petrochemistry of Bundelkhand Granites and Associated Rocks of Central India*. The published book on 'Geology of parts of the Bundelkhand Granite Massif of Central India' by Basu (1986) and was reviewed by Radhakrishna (1987), About a couple of years ago, Roday, et al. (1989) published paper on structural analysis of shear zones in Basement Granite and their relationship with folding, shearing and faulting in the cover sediments near Hirapur, district Sagar, Central India. 13
1.9.2. The Bijawar Group :
Everest (1833) made a route survey from Mirzapur (U.P.) to Sagar (M.P.) with close and accurate observations on the rock types encountered along the route. Later Coulthard (1833) who took a traverse in the area# described the ferruginous beds of Hirapur (Bijawars), the Vindhyan sandstone and the trap formation of the Sagar district. Subsequently, Williams (1852), was also reported to have surveyed a part of this ar«a but his papers and maps are not available for references in the G.S.I, library.
Medlicott (1859) was the first among the pioneer workers in this area to introduce the formation of the Bijawar princely state, Bundelkhand region as 'Bijawar series'. This series of rocks crops out more or less continuously extending from Bundel khand in the south of the Narmada river and Hirapur village. According to Medlicott (1860) the village name, Hirapur often occurs in the accounts of Bijawar and Upper Vindhyan Group of rocks. There seems to be some controversy over the limestones found there. He had previously placed the limestones in the Semri Series of Lower Vindhyan Group by virtue of their moderate beddings, massive, horizontal nature, pink colour, etc, later on included with the Bijawar Series. The occurrences of iron-ores and Hornstone-Ereccia in the Bijawar Series were also recorded by Medlicott (1852), 14
According to Mallet (1872) the patches of limestones north-east of Hirapur village which was conjectured to belong to the Lower Vindhyans and mapped as such, has been found on more detailed examination to be referable to the Bijawar Series.
According to Vredenburg <1901) the famous iron ores of Bijawar Series are of a different nature and appear to occupy the areas of faulting or crushing. These crushed rocks often consist of a breccia whose matrix is a mixture of silica and hematite of a bright red colour and they were found to be very similar in appearance to the bedded jasper. Krishnan (1948, 1959, I960 and 1968), wh6 has described a generalised account of the geological set-up of Bijawar Series gave a brief petrographlc description of rock types of this area. Dubey (1950) classified the different rock units of Bijawar Formations in the Bundelkhand region. Later on, Dubey (1952) has published a brief report on •Geology of the area in and around Heerapur in the Banda Tehsil, Sagar district, M.P. (India)'. He also analysed a few samples of Bijawar iron- ores just to assess their metal contents.
An integrated geological, geophysical and geochemical studies near Tighora village, Sagar district, M.P. led Rao, et al. (1969) to identify a number of shear zones represented by a single quartz-vein or en-echelon system of quartz-veins emplaced in the Bijawars in addition to some surface indications of copper mineralization. 15
Some scientific officers of Atomic Minerals Division, Department of Atomic Energy, Government of India (including the present author) discovered and reported for the first time from India the occurrence of some uranium bearing phosphorites from the Hirapur-Mardeora area, Sagar and Chhatarpur districts (M.P,) during the field season, 1975-76. Their findings of the uraniferous phosphorite from the area could be compared with any one of the world's topomost uraniferous phosphorite deposits like that of Nigeria, South Africa, U.S.A, etc.
Israili (1978) (Guide of the present work of the author) was the first person from India to report the origin and classification of Indian phosphorites in which, he had discussed briefly the petrography, geochemistry, classification and origin of the 'Bijawar phosphorites*. Pant (1980) reported some synclinal and anticlinal structures which are prominently displayed in the shales and Gangau-Perruginous Formations of the Bijawars occurring in the Hirapur-Bassia area, district Sagar (M.P.). The inter-layering of thick mud beds with relatively thin sand beds, which is conspicuous in Bijawar, was assigned to the characteristics of sediments of intertidal flats (Reineck and Singh, 1980). Haider and Ghosh (1981) discussed some uncer tainties in the dating of the Bijawar and the Vindhyan rocks. 16
Srivastava and Banerjee (1981) has published a paper on •Apatite Crystallite sizes of Precambrian phosphorites of India' in which they discussed briefly crystallite sizes and cell dimensions of Hirapur phosphorites district Sagar, M.P.
Later on Banerjee (1982) and Banerjee,et al. (1982) published two papers on •Lithotectonic phosphate mineralization and regional correlation of Bijawar Group of rocks in the Centra^ India* and •Precambrian phosphorites in the Bijawar rocks of Hirapur-Bassia area, Sagar district, M.P., India'. Saigal and Banerjee (1984) have published a paper on 'Proterozoic phospho rites of India' in which they discussed briefly the petrographic, geochemical and genetic aspects of the Hirapur phosphorites. The Hirapur, district Sagar (M.P.) and Sonarai, Lalitpur district (U.P.) phosphorite deposits occur in the Bijawar belt underlying the Vindhyan basin (Nath, 1984). Mahadevan (1986) has published a paper on 'Space controls in Precambrian uranium mineralization in India' in which he discussed briefly the uranium mineralisation in the phosphorites of Hirapur-Mardeora area. Recently, Misra (1987) published a paper on 'Bijawar and Vindhyan tectonics of Central India' (particularly of Uttar Pradesh and Madhya Pradesh) based on air borne, magnetics and ground geophysical survey. During field season, 1931-82, geologists of Geological Survey of India, namely, Ali, X.N.; Kumar, B. and Sonakia, A. carried out the field investiaations 17
in and around Hirapur-Mardeora phosphorite deposits, districts Sagar and Chhatarpur (M«P») and later on Nath, J.S. and Mukherjee, S»K.», Director-Generals of the above organisation published their investigation reports in the Annual General Report of G.S.I,, Calcutta in the year 1987. The contributions of the above investigators will follow in the coming chapters. 18
CHAPTER - II METHODS AND TECHNIQUES OF WORK
II.1. FIELD INVESTIGATIONS s
About 27 square miles of the study area was mapped on a scale - 2 inch to a mile with the help of Brunton compass and tape. The geological symbols indicated on the map are according to the International Geological symbols (Figure - in pocket). Stratigraphic contacts of the Bijawars with the underlying Granite Complex and the overlying Lower Vindhyans are the various lithological types and some structural features of the
Bijawars. During surveying, a total of 18 phosphate-bearing beds (shale-phosphorites, 5; ironstones phosphorites, 4; and quartz* breccia-phosphorites, 9) were identified in the field by testing with ammonium solution (NH.OH). In the shale phosphorites, which have under gone lateritization, cavities and voids are developed at places. The phosphorites with cavity and/void fillings are recorded as secondary phosphorites.The shales, ironstones, end quartz-breccia-phosphorites are of primary origin. The ironstone- phosphorite may also be recalled highly ferruginous-shale phosphorite due to higher contents of iron.
A total of 82 fresh samples, out of them 17 samples of Bundelkhand complex; 63 of the Bijawar Group and 2 of Lower 19
UI t— o < I— < < z o UI 03 o tr z U o s Q Q Ui U. O z UJ O CE V) o u. X UI o o u Ui tt. cr z Ui HI Q. 3 a a. Hi cO ^- en £ o I a. < ^ in X ."^X ui X ^.^^. X o •A^^, in a: 3 u m z 1 > u z < CL -1 3 cr o 1 O < *- HI < cr s Vindhyan Group each measured 6" x 4" x 2" approxinsately collected. The locations of 24 rock samples of phosphorites are indicated on the geological map of the study area (Figure - in pocket). The author also prepared the Geological Cross-section along the profile line A-B across the phosphorite beds, just to show more clearly the geological sequence of rock units of the study area (Pigure-4). II>2. LABORATORY INVESTIGATIONS J 11.2.1, petrological Investigations s The rock samples thin sections were prepared. An account of the megascopic and microscopic characters of the various lithounits of the Bijawar Group is given in some detail in the following chapter. The primary phosphorites (shales, ironstones and quartz-breccia) and secondary phosphorite were examined under the Scanning Electron Microscope (SEM) to describe in detail the sub-microscopic petrographic characters of some fine-grained phosphatic rocks. X-ray Diffraction study of both the primary and secondary phosphorites were also carried out in order to identify some doubtful minerals. 11.2.2. Geochemical Investigations s II.2.2.1. Crushing and Powdering of Samples : The following procedures were adopted to prepare the rock samples for their chemical analysis. About 5 0 gms. of 21 each rock sample was taken for crushing and powdering, which were done as follows :> 1. Crushed in a steel nusrtar to coarser fractions. 2. The partly crushed material was further crushed in porcelain mortar till it became medium to fine grained. 3. Finally* the material was finely powdered upto 300-400 raesh sizes in an agate mortar. 4. The finely powdered rock was then transferred into polythene bags, numbered and packed properly for analysis. II.2.2.2. Procedure adopted for Geochemical Analysis : The powdered rock samples of Bundelkhand complex, Bijawars and Lower Vindhyan Groups were selected for the determinations of their major oxides llke^siO,, ^^0^3' ^^^2' MnO,CaO, MgO, ye2°3* ^®°' ^^2° ' ^2°* ^2°5 ^"*^ ^2°^ ^^ adopting the procedure followed by Shapiro and Brannock Two types of solution 'A' and 'B* were prepared. Solution *A* was used for the determinations of SiO- and Al-O, and solution •B* for the determinations of TiOj, MnO, CaO, MgO, Fe 0-, Na,©/ KjO and PjOs* The oxides like, SiO^, AI2O2, Ti02, KnO, total iron and P2O5 were determined by Beckman DU-2 spectrophotometer using various wave-lengths following USGS standards {pGV-l, BCR-1 and GSP-1) for each major oxides. CaO and MgO were analysed 22 by titration method with EDTA using Erichrome Black Indicator-I, FeO was also analysed by titration method using potassium di- chromate solution treated by diphenylamine sulphonite as an indicator. Both NajO and K2O were determined with the help of flame photometer. Water (HjO*) was determined by using nine inch long hand glass ignition tube (0.2* inner diameter) consisting two bulbs one at the end and the other at the middle part of the tube. One tube was separately required for each rock sample. The individual weight percentages of all the above major oxides were calculated and obtained data are properly placed in Tables-II and ill. Carbon-di-r oxide (CO2) was determined volume trie ally in a series of 250 ml beakers, 0.5 gm of calcium-carbonate (CaCO^) as standard and 0.5 gm of powdered sample was placed. 25 ml of hydrochloric acid (HCl, 0.5 N) was added to each beaker and allowed to remain overnight. The remaining acid in the beaker was titrated with sodium hydroxide (NaOH, 0.35 N) and Bromo- phenol blue was used as an indicator, which gave yellow to blue end point. The calculation for CO- in per cent was aade as stated below j- 1. Calculated the acid alkali ratio - ^ 25 volume of NaOM for blank 2. Multiplied each of the NaOH titration values by the acid alkali ratio. 23 3. Substracted each figure obtained in step 2, from 25 ml HCl. This gives the HCl in millilitres consumed by the carbonates. 4. A factor was obtained on the basis of titration of the standard CaCO, (This standard contains 44 per cent COj) - 44 ' MCI consumed by standard * FACTOR 5. Multiplied each sample value for HCl consumed as obtained in step 3 by the factor to obtain COj in per cent. 6. Where POOR is greater than few tenths of a peifjcent corrections were made by multiplying its value by 0,67 and subtracting this from the value obtained in step 5. Total 50 representative rock samples, out of total S2 were selected for the determination of trace elements like, Ni, Co, Cu, Cr, Ga* Pb, V, U^O- and Zn adopting procedure followed by Naqvi and Husain (1972), Among them Ni, Co, Cu, Cr, Ga, Pb, V, Cd, and Zn were determined by X-Jtay Flourescence (XRP) techniques and UgOg with the help of Atomic Absorption Spectro photometer. The calculated values of the elements in ppm and weight percentages are given in Tables-IV and V, An attempt was also made to determine the content of organic matter, sulphate, Y, Zr and Sr but their presence are almost negligible particularly in the phosphate-bearing rocks. CHAPTER - III 24 LITHOSTRATIGRAPHY & STRUCTURAL CONTROL OP PHOSPHORITES III.l. GENERALISED GEOLOGICAL SEQUENCE OF BIJAWAR BASIN : The generalised geblogical sequence of entire sedimentary Bijawar basin which covers a large part of Madhya Pradesh and a few parts of Uttar Pradesh, India has been discussed in the last volume previous workers. The Bijawar basin which canprises rock formations of different ages starting from the oldest/ Archean (Bundelkhand Complex covers nearly one half of the total area of the Bijawar basin and the rest is occupied by sedimentary formations. Among the earlier workers, Krishnan (1949) and Dubey (1952), classified the stratigraphy of the Bijawar basin, which is presented below «- Table-VI : Generalised Geological Set of the Bijawar Basin. System ~ series ~~ General Succession Formations (After Krishnan, 1949) (After Dubey,1952) 25 Upper Rewa Sandstone Conglomerates a < Semri Jhiri Shales and Sandstones Lower Rewa Sandstone -Unconformity- 2@ Panna Shales UNCONPORMITY Ferruginous Sandstone X Hornstone-Breccia with pockets of Hema and Iron-ores < tite. Q Bijawar Siliceous-Limestones Shales g and Hornstone-Breccia, Limestones Quartzite & Sandstones 2: < Basic-Dykes Dykes Bundel Quartz Veins Quartz Veins khand Pegmatites a Complex Schists Schists < Gneisses Gneisses Granite Granite 25 Subsequently, Rajarajan (1978) of the G.S.I, who carried out the systematic geological mapping of the Bijawar rocks around Sagar and vfestern part of Damoh district, Madhya Pradesh proposed the following classification of the Bijawar rocks. Which is not much different from those of Krishnan (1949) and Dubey (1952). Table-vii $ Generalised Geological Set of the Bijavar Basin. Lower Vindhyans Semri Series Semri Formations .- UNCONFORMITY Ferruginous Quartzites occasionally coarse Bijawar Series Red shales with Pre-Riphena pockets of iron-ores Group (Transition Reibung-breccia Series) (Hornstone-breccia) Siliceous-magnesium Limestones. EPARCHEAN - NON-CONFORMITY Archaean - Bundelkhand Complex Also Mathur and Mani (1978) independently made an attempt to classify the rocks of the Bijawar sedimentary basin more or less on the same lines as the earlier workers but defining precisely the nomenclature of the formations of the Bijawar Series of rocks as given below :- 26 Table-VIII : Generalised Geological Set of the Bijawar Basin. Lower Vindhyan Group Semri Formations (Upper Proterozoic) UNCONPORMITy Gangau Ferruginous Tillites Formations Shales Ferruginous Congloaerates, Breccia and Phosphorites Bajna Dolomites Bijawar Group Amronia Quartzite (Early to Middle- Proterozoic) Dargawan Traps Malhera-Breccia UNCONFORMITy BUNDELKHAND COMPLEX . BUNDELKHAND GRANITE & GNEISSES (Archean) III.2. GEOLOGICAL SEQUENCE OP THE STUDY AREA t Following the observation made by the earlier workers, as stated above, on the geological successions of the Bijawar basin, the author made an attempt to study the stratigraphy of the Hirapur-Mardeora area, Sagar and Chhatarpur districts, M.P. 27 (India) after mapping it in greater detail on the scale, 2 inches to a mile covering about 27 sq. miles falling within longitudes, 79°9'0- E : 79°14*0" E and latitudes, 24°19'0«« N j 24°23*0" N. Hie stratigraphic succession of the study area is given as below* Table- ijc Lower Vindhyan Semri Group System (Late/Upper Precambrian) UNCONFORMITY II Quartz-Breccia Gangau phosphorites. Ferruginous Ironstone- and Phospha- phosphorites. Bijawar tic Formations Cuddapah Group (After Mathur Shale-phosphorites, System (Early to and Mani, at places weathered/ Middle 1978 and leached formed Precambrian) Banerjee, secondary et al.,1982). phosphorites. Non-Phosphati c Formations UNCONFORMITY Archaean - Bundelkhand Complex 28 The stratigraphic, petrological, lithologlcal and some structural features of each rock formations of Bundelkhand Complex, Bijawar and Lo%*er Vindhyan Groups ranging in age from Archean to Late Precambrian of the Hirapur-Mardeora areas are given as follows s- III.2.1. Bundelkhand Complex (Archaean) s The age of the Bundelkhand granitoid massif is around 2100-2400 Ma, the type Bijawar, which unconformably overlies the granitic mass, is considered to be not older than x.arly Proterozoic (Proterozoic I), (Sarkar, et al., 1984). A large, bluntly triangular tract but slightly foliated granite occupies the northwestern half of Bundelkhand, most of the Sagar, Chhatarpur, Gwalior and Datia districts of Madhya Pradesh and adjoining other states of India. This granite passing into a strongly-foliated gneiss upon, which as well as upon a Gneissic Complex. The tract is sharply bounded by a scarp, several hundred feet in height of Vindhyan or of Bijawar rocks, which through ancient are younger than the granite. The granite some times form hills, but the general features of the ground are gently undulating, sparesely-cultivated uplands with shallow valleys and alluvial plains, transversed at an interval by quartz- veins in the form of abrupt wall-like ridges (Pascoe, 1965). 29 The main rock unit of the Buncelkhand Complex which covers most of the part of the region occupying the north western half of Bundelkhand, most of tsie Sagar, Chhatarpur, Gwalior and Datia districts of Madhya Pradesh and also some deposits in the states adjoining M.P., is usually a massive granite. Occasional occurrence of banded or crudely foliated equivalent rocks in certain areas td.thia the granite does not make any change in the nomenclature of the Bundelkhand Granite. Due to wide variations in mineralogy and structures of the granite and gneisses from place to place« these Archaean rock formations have been grouped together as 'Bundelkhand Complex* that formed the basement sequence in the Hirapur-Mardeora area. The Bijawar Precambrian rock group overlies the basement rock group with a proposed unconformity at its base. According to Bandopadhyaya and Roy (1987), the litho- stratigraphy, structure and tectonics of the Bijawar of tiie Son- valley point to an ensialic interplate (?) basin or geosyncllne which evolved into an ENE-WSW trending linear belt within the Indian Shield. They also reported thar the Bijawar rocks are unconformably overlain by the Vindhyan Supergroup in the north and by the Gondwana Supergroup in the south. The Bundelkhand Complex comprises granite, granite- gneisses, /gneissose-granite, schists and later intrusives (Jhingran, 1970). 30 The Complex, which possibly contains some of the oldest metasedimentS/ is primarily a granitic unit. The associated metasediments are believed to be part of the early sedimentary package which provided a floor to the subsequent granitic intrusions and sediments. These sediments are believed to have been granitized in different stages, giving rise to different types of granites and migmatites (Baherjee, 1982). III.2.1.1. Granites s It is now considered to be mainly a metasomatic granite, which has assimilated older rocks and contains inclusions of quartzites, mica-schists, talc-schists, amphibolite, etc. (Jhingran, 1958 and 1970). The chief characteristic features of this granite and its massive structure, its obscurely developed foliation and the rarity of accessory minerals. It is a medium to coarse grained rock consisting chiefly of orthoclase, hornblende and quartz. Sometimes, superficially weathered plagioclase occurs much smaller in crystal size than that of orthoclase and always in quite suborinate amounts. The greater prevalence of large red and pink orthoclase-feldspars gives the rock its characteristics appearance (Figure > in pocket). 31 111.2.1.2. Granite Gneisses : The Bundelkhand Gneiss Is predominantly granitic In appearance, gnelssoslty being developed only at few places. About 0.80 km. north of Agra village the granitic gneiss shows foliation along NlO°w - SlO^E direction and here the rock Is rather white uhlike the usual pink variety (Rajarajan, 1978) (Figure - in pocket). 111.2.1.3. Schists : These are represented by different types of schistose rock units and from the major part of the Bundelkhand complex which occur in between Bundelkhand (on the west) and Bljawars (on the east), (Jhingran, 1958). The metamorphltes such as quartz-pyrophylllte-schists, quartz-schists, chlorlte-schists, hornblend-schists and phyllltes occur as an inclusions In the dominant Bundelkhand granite mass which has developed faint gnelssoslty at places (Rajarajan, 1978). In the Hlrapur-Mardeora type area, there are three types of schists occurring namely, sericite-schists, quartzose-schlsts and chlorlte-schists. These schists generally show east-west trends and steep southerly dips amount varying from 70° to 85°. The serlclte-schists occur near the Forest Rest House, Hlrapur 32 and about 1,70 km. southeast of Hirapur village. These schists have the appearance of talc-schists on account of their soapy 11 touch in hand specimens. The quartz-schists outcrops also seen near Tighora and Bassia villages. The chlorite-schists are not very common in this area. About 2 km. northwest of Mardeora# there is a band of chlorite-schist inclusion in granite (Figure - in pocket). Among the coimion varieties of intrusives« which are post Bundelkhand Complex but pre<*BlJawars, mention may be made of veins of pegmatites and quartz, and of basic dykes. III.2.2. The Biiawar Group (Early to Middle Precaaabrian s Medlicott (1859) first coined the name *Bijawars* for the pile of low grade metasediments occurring just south of the Bundelkhand massif. Later on, he (1860) designated the formation as 'Bijawar Series* after the type area in the former Bljawar state in Bundelkhand region. The type area that lies south of the Narmada river has a total thickness of less than 240 meters. According to Mallet (1872) the Bijawars that often begin with a basal quartzite are followed up by limestones which are mostly siliceous. He also observed that sometimes siliceous limestone occurs as basal member in place of quartzite. The siliceous nature has been explained as the effect of shattering together 33 with alternating strata of limestone and quartzite giving rise to an intermixed mass of siliceous-limestones.The basal quartzite and siliceous-limestone are overlain by ferruginous and siliceous- shales, iron-stone, iron-ores, homstone or quartz-breccia# etc. According to Krishnan (1949, 1968) and Dubey (1952) the quartzites and sandstones and sometimes conglomeratic form the basal members of the series resting on unconfomably over the Bundelkhand Gneissic Con^lex. Siliceous-lime stones and homstone- breccia are also associated with the quartzites. These are rather irregularly distributed and are of less than 60 meters In thick ness. They are overlain in turn by ferruginous sandstone contain ing pockets of hematite. The rocks are either horizontal or have a south-easterly dips, though at a few places in the south they have been subjected to crushing and disturbances before the Vindhyans were deposited. In the Hirapur —Bassla area« the Bundelkhand granites are either directly overlain by Bajna Dolomite or juxtaposed against the 'Gangau Ferruginous Formations* made up of conglomeratic-breccia and shales. There is no tillites in the vicinity of the phosphorite horizon but it has been recorded in the adjacent regions (Mathur, 1960 and Mathur and Mani, 1978). Open synclinal and anticlinal structures are prominent in the shales. The Gangau formations is bounded by the synformal structures in the Bassia area. Also similar phosphorites occur 34 at Sonrai area in the western Bijawar basin, district Lalitpur, Uttar Pradesh, where Cu, Pb, Zn and U-minerels are intimately associated with the secondary phosphorite horizons (Banerjee, et al., 1982). The major rock types of the Bijawar formation include siliceoas-magnesiaro-liinestones, Riebungs-breccia or homstone- breccia and red shales. Systematic mapping of the formations by Rajarajan (1978) indicates that the Bijawar rocks constitute an asymmetric anticline and a syncline plunging towards south-east The Bijawar sediments alongwith associated volcanics lie either directly on the Bundelkhand granites or the granite-gneisses of the basement or on the metamorphic foliated schists (Krxshnan, 1968 and Banerjee, 1982). The *Bijawar Group'of rocks exposed in the type area of Bijawar and in the Jhansi-Lalitpur districts have been studied fairly well by Mathur (i960) and Mathur and Maal (1978) and Prakash, et al. (1975), while Misra and Sharma (1975) have extended the realm of Bijawar sedimentation farther north into' the heart of Bundelkhand massif. The Bundellchasd granite massif possibly behaved as a shallow platform with predominance of clastic component due to higher relief of the northern land area. With the passage of time and chemical ccntrcls excerted by the atmospheric agencies during the early Froterozoic era, carbonates alongwith associated argillites were precipitated 35 at the sediment-water interface and accumulated in the shallow open expanse of the littoral sea* vrfiose shallow undulating floor was made up of granites and metamorphics. Repetition of argillites and arenites in the southernmost Bijawar outcrops indicates the presence of a southern cratonic mass which limited the southern and eastern extents of the Bijawar sea. The sedi mentation is being largely controlled by the neighbouring cratonic mass as well as by the sharp undulations of the basement topography. This southern cratonic mass has apparently disappeared through denudation^ subduction due to reactivation of Son-Narmada lineament and out-pouring of the Deccan lavas during mesozoic times (Banerjee^ 1982). A general review of the Bijawar rocks and adjoining areas shows that the Upper Bijawar of the type area designated as the *Gangau Ferruginous Formation* in the east seems to have been overlapped by a regressive cycle of sediments represented by clastogenic sequence on the western part of the Bijawar basin. If such was the case, the 'Sonrai Formation* and *Gangau Ferruginous Formation* could be considered fades variations f representing changes from an argillaceous-phosphate-conglomeratic facies in Hirapur-Bassia area to a dolomitic-sandy-phosphate-facie in Sonrai area. Numerous primary beddings in the associated clastic units and occasional sandy carbonate layers are indica tive of an all prevading shallow sea whose depth never exceeded 36 beyond the intertidal zone, in most cases, the primary struc tures indicate quiter environment fairly protected from the turbulent open-sea by numerous basement uplands which gave ponded character to the shallow marine Precambrian littoral basins of the Central India. These palaeodepressions were strongly influenced by the palaeo-topography provided by the primordial Bundelkhand Complex (Banerjee, 1982), During subsequent tectonic episodes, the basement conqolex with its early meta- sediroents (e,g. Kukraicha Formation of Misra and Sharma, 1975),, were folded, faulted and locally migmatized. Consequent to stabilization of the Bundelkhand Platform heralding a period of emergence and submergence of landmass, the Bijawar sediments were deposited on an eroded peneplanned surface with breccia and matrix-supported conglomerates at some places, ferruginous fine grained sands at other and fine carbonate muds with minor sands at still other place, well within the same Bijawar littoral waters. The distribution of sediments was apparently controlled by the amount and nature of river transport and dispersal current in the Bijawar basin (Banerjee, 1982). intermittent basic volca- nism provided ingredients for the enrichment of phosphates in the basinal waters. Towards the close of the Bijawar sedimenta tion in the eastern Hirapur area, the basin was filled up and the land areas developed, while towards the west around Sonral, sedimentation continued in extremely shallow sea with abundant continental type of sedimentation in the border land (Banerjee, 1982). 37 In the Hirapur-Mardeora area the Bundelkhand Granite Complex constitutes the basement over which the Bijawar Group of rocks (Early to Middle Precambrian) were deposited with a sharp unconformity. These Bijawars were in turn overlain unconformably by the Lower Vindhyan System of rocks which belong to Late Precambrian age. The Bundelkhand granites occur mostly in the eastern and western parts of the study area. The Bijawar Formations occupy some portions mainly in the southeast and northwest sides and the Lower Vindhyan system mainly in the southern and eastern part of the area. Though the quartzite is the basal bed member of the Bijawar Formations lying over the Bundelkhand Conqplex, at places limestones, shales, ironstones« iron-ores« quartz-breccia and phosphatic rocks also lie directly over the Bundelkhand conqplex. The quartzite is generally overlain by limestones which in turn are successively overlain by ferru ginous and siliceous shales, ironstones and iron-ores and quartz- breccia. These ferruginous, siliceous and non-phosphatic shales, ironstones and iron-ores and quartz-breccia are further succeeded by ferruginous, phosphatic and uraniferous shales, ironstones and quartz-breccia. At places, these phosphatic rocks are over lain unconformably by sandstones which is ferruginous, quartz- itic and conglomeratic and belong to the Semri Group of Lower Vindhyan System. There is no evaporites, tillites, stromatolites. 3S Dargawan-traps and volcanic flows in the vicinity of Hir=pur- Mardeora area as reported by earlier workers in other parts of the basin (Mathur and Mani, 1978; Rajarajan, 1978 and Banerjee, 1982) (Figure . In pocket and Tables-VII & VXII). The Bljawar Group cover sediments (Bajna dolomite and Gangau Formation, ^^^ 1800 m.y.; Crawford, 1970) have a basal 30 to 40 metres thick carbonate member dolomite or dolomitic- limestone which contains well-rounded pebbles of granite, pegmatite and vein-quartz at the base, suggestive of the widespread erosion of the basement prior to the laying down of the Bijawar cover sediments. There are evidences of moderate- scale slumping in the basin associated with convolute bedding and minor scale high angle reverse faults. C3>ertificatio3 and silicification are dominant in almost all lithounats (Roday, et al., 1989). In course of surveying, mapping and saonpling, the author came across some common primary sedimentary structures in the non-phosphatic as well as phosphatic Bijawar rocks in the Hirapur-Mardeora area. They are rain-drops iirorints; ripple- marks; horizontal, cross and wavy laminations; current bedding, concretions, mudcracks, grooves, striations, etc. Besides these primary structures some secondary deformational structures like micro- to megascopic folds, minor scale slippages, probable faults and penecontemporaneous contortions etc. were enccantered in all the rock types and talcose bands particularly in lime- 39 -stones also seen. The tensions fractured, veins* voids/cavities/ pore filling features are also associated with them particularly in secondary phosphatic rocks (Figure - in pocket). The folds encountered in the study area vary from sharp kinks to gentle warps. They are dishannonic in respect of both axial trends and intensity of folding. The plunge of these folds varies from northeast to southeast. The amount of the plunge of the folds varies from 20° to 40°, Panning and cuxrvilinearity of the axial trends of these folds is a common feature. This non uniform nature of the folds was possibly guided by the surface irregularities of the basement (Bundelkhand Complex) and also relative competence of the rocks. At places* some instances of flow folding of quartz layers particularly« in limestones on the Sagar-Chhatairpur road were recorded. The faulting may be the cause of brecciation of the quartzites and other rocks forming hornstone or quartz-breccia. Siliceous and ferruginous materials occupy the fracture spaces and bedding cleavage in some lime stones and quartzites. Brecciation is not confined only to the quartzites but ha^ also affected the ferruginous shales, iron stones, sandstones, etc. (Figure - in pocket). The compositional and lithological characters of the different lithological types of the Bijawar formations of the study area are described in some detail as follows :- 40 III.2.2.1. Quartzite : Quartzite is the more common type of basal rock of the Bijawar Formation. It is generally medium to coarse grained. Occasionally* it appears pebbly consisting of pebbles of white quartz. The general strike trend of the quartzitic bed is east- west and dip 4° to 8° due south. The secondary veins of silica delineated along the bedding plane partings of the quartzitic bodies. The Bijawar Formations often begin with a basal quartzite and are followed up by limestones which are mostly siliceous (cherty). It is also observed that in these Formations* sometimes in place of quartzite, siliceous-limestone forms the basal member. In the Hirapur-Mardeora area* occasionally* in place of quartzite, which formed the basal bed of Bijawar Group, limestones, ferruginous shales, iron-ores and ironstones, and quartz-breccia occur as basal beds. At places the quartzites which is sorwtime brecciated contain angular to subrounded and rounded pieces of quartz. The angular to subrounded fragments of quartz are embedded in an iron-oxides matrix. It is generally reddish in colour and medium to coarse grained. The reddish colouration is obviously due to the presence of iron-oxides (Figure - in pocket. Table-IX). III.2.2.2. Limestones : Limestone which, at places, is dolomitic in nature, occurs conformably over the quartzites and at other places, directly 41 overlies basement of granite-gneisses and schists of Bundelkhand Complex with all unconformity at its base. It strikes nortHeast with a maximum dip of 16° south and 40° east (Krishnan, 1949). The siliceous nature of the limestone has been explained as an effect of shattering together with alternating strata of lime stones and quartzites giving an intermixed mass of siliceous- limestones (Mallet, 1872? Dabeyv 1952 and Krishnan, 1968). The limestone formed the valley floors because of its greater susceptibility to chemical weathering. The rock, too is highly siliceous and is associated with thinjlayers of silica and shapeless aggregations of chert. However, massive limestone forms major part of the sequence in the Bijawaf Series (Dubey, 1950 and Krishnan, 1968). The limestone is white to pale, dark-grey in colour, fine grained. It shows 'Karst* and forming small dome like masses. Within the limestone terrain a number of basic dykes and quartz-reefs occur and the contact between the(dyke/reef) and limestone is simple (Jhingran, 1958 and 1970). The fine-grained Bajna dolomites are of two types namely, (a) brown ferruginous dolomite and (b) grey dolomatic limestones. The first type grades into overlying 'Gangau Formations•. Their composition vary from cherty and shaly dolomite to pure dolomite rock (Mathur and Mani, 1978). 42 The limestone is usually bluish-grey in colour, though it is occasionally interbanded with light grey and dark grey varieties. The dark grey limestone is calcitic and pare, but it is subordinate in amount. A representative sample of the common bluish grey-limestone of Hirapur contains 54,74% of CaCO- and 23.61% of MgCO^, indicating its high magnesia content. This limestone is, therefore, unsuitable for cement, flux or chemical industries (Rajarajan, 1978). Siliceous (cherty) veins are common in the limestones though there also some veins of iron oxides which are rather rare. The presence of some talcose bands in limestones indicates localized low grade metamorphism of the limestone. The limestone is very fine grained, thick and contact. Some limestones and intercalated with chert, especially a furlong NE from the Hirapur Rest House. It interceptively grade into the overlying shales through calcareous shales. The general strike of the limestone is north-south and dip 10° to 35° due east and at places due 10 west. At places, the strike of the limestone is north-east southwest and a southerly dip of 12°. The bluish grey variety of limestone is more or less highly dolomitised. The 'Karst* topographic feature is developed in the limestones particularly, near the Hirapur village and along the cutting of Sagar-Chhatarpur road (Figure - in pocket and Table-IX). 43 111.2.2,3. Shales : I ^ _ The *Gangau Formations* on the the other hand are composed of ferruginous-breccia* conglomerates and reddish- brown slates and shales. Ferruginous sandstone and shales occur as intercalation within the ferruginous conglomerates and breccia with abundant apatite grains in the groundmass (Hathur/ 1960 and Mathur and Mani, 1978). About 4 km. ENE of Tighora* the limestone beds azre intercalated with slaty rocks ^rfiich are exposed in the valley sections between the hills. These rocks show rhombohedral cleavage and dip at 60*^ due S40°w. This indicates compression and folding of the strata here and the rock appears to be an indurated calc-shale. About 1.60 km ESE of Hirapur, some shaly rocks having the appearance of phyllite which are white, grey and purplish in colour exposed in the Kauthan river. They show a dip of 20° due SlO°w. About 1.60 km, southeast of Hirapur, the arenaceous-shales in the stream section show a dip of 70° due WSW near the contact of the Archean inlier, (Krishnan, 1949; Dubey, 1950 and Rajarajan, 1978). In the study area* the shales lying over the limestones conformably but at places these shales are directly resting over the basement rocks of Bundelkhand Complex. There are lot of structural and j^trological variations in the shales namely 44 as ferruginous shales, calc-shales, siliceous (cherty) shales, very high ferruginous shales (ironstone)^ quartzitic>sandy shales, phosphatic shales, ironstones'-shales, lateritic-shales, etc. Due to much variations in the rock types of Bijawar Formations, Medlicott (1860) makes the following pertinent observations on the Bijawar Formations, "I could not separate any safely defined subdivisions, although there is a large variety of rocks. They are so tossed about the mixed that it must be a work of considerable detail to discover the true order and grouping, if indeed any noticeable division exist.** This observation of Medlicott (1860) appears true if one takes a traverse along the 'Bijawar Formations*. However, the systematic mapping of the formations appear to indicate that the Bijawar rocks constitute dn asymmetric anticline and syncline plunging towards southeast, considering the contorted nature of the strata, although the dip amounts recorded in some places are rather low (Rajarajan, 1978). Most of the shales are ferruginous, siliceous (cherty) and at places highly phosphatic also. The primary and secondary structures are mostly common in non- phosphetic and phosphatic shales, ironstone and quartz-breccia in the study area. Thus, the author will discuss in detail all types of structures in phosphate bearing shales, ironstones and quartz-breccia, and this will be helpful in dealing with the geochemical and genetic aspects of these rocks. The reddish- 45 brown colour of these shales may be due to the presence of iron-oxides and/secondary iron-coatings (Figure - in pocket and Table-IX). 111.2,2,4, Ironstones (Highly Ferruginous Shales) and Iron Ores ! According to Vredenburg (1901) the famous iron-ores of •Bijawar* are of a different nature and appear to occupy areas of faulting or crushing. These crushed rocks often consists of a breccia* whose, matrix is a mixture of silica and hematite of a bright red colour, very similar in appearance to the bedded jasper. There are beds of red colour iron-ores that occur in the Bijawar Series, in which the proportion of iron is often so high due to which they could be considered as valuable ores of iron (Krishnan, 1949). The bodies of iron-ores are found as pocket fillings or lenses or associated with the shales. Most of the iron-ores that is found in this area is of a pellety or concretionary type with small rounded and oval pellets cemented together in a ferruginous matrix. Besides this, a massive compact variety of iron-ore is also found rarely as in case of the deposit south of Hirapur Forest Rest House and about 1/2 mile from it. The iron-ore bodies along the Damoh-road and towards Kachhar and 46 Mardeora sides are all of pellety type. Some of the pellets of the Iron-ores are oval in shape exceeding the size of an egg, but usually they are a little bigger than peas (Dubey, 1950). Dttbey (1952) determined the percentages of iron from the top and middle portions of the iron-ores samples occurring northeast of Hirapur village about two furlongs from the Forest Rest House, Hirapur. The obtained geochemical analysis results of top sample, the 5'e202 content, 22.25% and middle 6.44% respectively. Very rarely massive iron-ores are also noticed in this area. The iron-ores do not show any kind of bedding or any significant sedimentary features in any part of the study area. It may possibly be suggested that the ores have its origin to the leaching of iron from the ferruginous sandstone that was overlying the shale. Ferruginous sandstone has been mentioned to be occurring above the limestone and hornstone-breccia in the Bijawar series. It is just possible that the iron-ore deposits at present occurring may be due to leaching of iron whicA was concentrated in shales (Krishnan, 1968). There is a prominent outcrop of black cherty rock about 1.20 km northwest of Hirapur. This rock appears to have been formed by metasomatic replacement of the limestone by ferru ginous solutions followed by oxidation and extreme silicifi- cation. This process is envisaged by formation of chalybite in 47 the first instances, producing magnetite on further oxidation and subsequent silification of the whole rock. This black cherty rock is thus identified as a silicified ironstones, (Rajarajan, 1978), In the Hirapur-Mardeora type areas, the shales are overlain by highly ferruginous shales (ironstones) and pockets Of iron-ores at places. It can also be suggested on the basis of field observations that the shales are slowly grading into the very highly ferruginous-shales at places. The presence of iron bearing minerals like magnetite, hematite, limonite, etc. this rock can be recalled as ironstones and iron-ores. At places these ironstones and iron-ores are directly resting over the Bundelkhand Complex and dolomitic-limestones and overlain by quartz-breccia and sandstones. Near the contact of pockets of iron-ores, the shales have become very highly ferruginous and showing very bright red colouration. They weathered into biscuit like pieces on the Hirapur-Damoh and Hirapur-Sagar motor roads and their dip and strike confirm with that of the underlying limestones. The pellets of iron-ores are oval and rounded in shapes. Within these pellets concentrations of hematite iron- ores are to be noticed. In the early days these pockets of iron-ores gave rise to small local industry of iron smelting. Iron leached from this, appears to have red coloured the under lying shales and even percolated into them making at least the contact portions highly ferruginous. These facts can be observed throughout in the study area. The strikes of the ironstones in the area are north-south and north-east-southwest dipping around 45° due east and 8 to 16° due north-westerly. The pockets of ironr-ore« do not show any definite strike directions and the amount of dip is very low (Figure - in pocket and Table-ZX)• 111.2,2.5. Quartz-Breccia or Hornstone-Breccia : Medlicott (1859) stated that the quartz-breccia overlies the pellety iron-ores of Bijawar Series. The breccia consists mostly of angular fragments of quartz« differing in size with sporadically rounded fragments. The individual fragments are held together by means of a jasperoid cement which might have acted as the dominant constituent with a lesser amount of feldspars. Mallet (1872), presumed that shattering in situ and deposition of silica in cracks from solution in water could be a possible cause for the origin of hornstone-breccia. The Bijawar age of the Mehdikhera chert-breccia and Lohar dolomite have been suggested by Blanford (1869) and Bose (1884) on the basis of their stratigraphic position between the Archean metamorphics and the unmetamorphosed Vindhyan sediments, Krishnan (1949) and Dubey (1950) discussed the hornstone-breccia as a compact, yellow, brownish to red in 49 colours in which angular fragments mostly of quartz occur. Roychaudhury and Sastry (1954) pointed to the singular petrology of the chert-breccia (as a silicified-breccia) with lack of notable bedding or foliation and its peculiar outcrop pattern (as isolated, linear ridges or escarpments fringing the Vlndhyans and proposed that they represent a post-Vindhyan fault breccia. They also recorded •intercalated* dolomite and sandstone block within this horizon. Considering all aspects of this formation in the area# this type of rock conforms to the definition of *R16bungs- breccia* described by Pettijohn (1957) as follows - "More common are the fold breccias or Rieburgs-breccia, which are the result of sharp folding of thin bedded brittle layers between which there are incompetent plastic beds. Inter-bedded chert and shale are likely to form a Reibungs-breccia on sharp folding. Such breccia are local and confined to sharply folded strata and are likely to pass into unbroken beds*. This description of the breccia by Pettijohn (1957) aptly agrees with the field observations and hence it is desired to term this group of rocks as *Riebungs-breccia'. It is significant that this breccia forms the limbs of the asymmetrical anti clinal and synclinal folds and also a part of the synclinal* being younger than the massive limestone beds (Rajarajan, 1978). 50 Heron (1959) described these breccia as 'hornstone- breccia* which formed irregular and massive beds and reported that they might have originated due to compressive stresses acted upon the formation, which consists of massive limestones overlain by thin bedded quartzites with intercalations of softer argillaceous rocks, like slates and shales. The underlying thicker formations, being competent, withstood the istresses without folding or crumpling, whereas the brittle quartzites with intercalations of some argillaceous rocks had yielded to the forces of plication resulting in the compact breccia, unfolded lie of the formation. Siliceous (cherty) llmestcxies and quartz->breccla are found associated with the quartzites. These are rather irregu larly distributed and are of less than 60 metres in thickness. These are overlain by sandstone containing some pockets of hematite. The rocks are either horizontal or have a low south easterly dip, though in a few places in the south, they have been subjected to crushing and disturbances before the Vindhyans were deposited over them, (Krlshnan, 1968). According to Rajarajan (1978), the limestones beccwie progressively more siliceous towards the top of the formation and ultimately merge into a compact breccia constituting the high hills. The hills of the Indora Reserve Forest and the prominent hill, southwest of Tighora are entirely formed of 51 this type of rock which varies in their physical characters such as the density of pebbles, silicification and compaction both laterally and vertically. The thickness of the formation in the different hill sections varies from 46 metres to 92 metres. The pebbles in this breccia are composed of guartzite, vein- quartz and chert which show considerable variations in size, such as from 1.30 cm to 0.62 cm and 10 cm. to 7.5 cm. Some of the pebbles are rectangular in shape. Sometimes, only small quartz-grains are seen in a reddish-ferruginous matrix. But the rock as a whole being quite compact and tough formed conical hills of some topographic eminence. It merges into massive quart- zites and occasionally slates and shales. The quartzites have been further silicifled and generally ferruginated with reddish- brown iron-oxides. Under the microscope, the breccia shows angular fragments of quartz, quartzite and chert in a matrix of quartz granules coated with reddish-brown ferruginous films of iron-oxides. In the Hirapur-Mardeora areas, the quartz-breccia is lying over the ferruginous shales and ironstones and iron-ores but at places it is directly resting over the Bundelkhand Complex, limestones and the underlying unconformably below the sandstones of Semri Group of Lower Vindhyan System. It is ferruginous, massive, irregular and bedded deposits. The breccia consist of angular to subrounded fragments of quartz, quartzite, chert and 52 rarely schistose rocks. The silicification and ferruginisation is a common features in this breccia* Divergent views have been expressed regarding the origin of these breccia. One group of geoscientists believed them to be of tectonic origin while others assigned thea to slipping of one formations over another less competent forma tion as a depositional feature. It is presumed that shattering and faulting locally of older rocks (schists, quartzites, etc.) and deposition of silica in cracks and interspaces of the angular fragments of the rock could be the possible cause for « the origin of the quartz-breccia. The quartz-fragments are of two genetic types viz., i) of igneous origin and ii) of secondary origin %«hich consists of angular to subrounded fine to medium grained quartz fragments, The subrounded to rounded sized particles indicated that the material was transported for a long distances from the source rocks. Itie general strike of the quartz-breccia varies from east-west to northeast-southwest with a true dip around 13° due North and 20 southeasterly in this area. The pockets of iron-ores and ironstones and quartz-breccia, definitely nrar" III.2.2.6 Shale Phosphorites : The author has already mentioned under the head 'Previous Work* that the phosphorites of the study area was discovered recently by the scientific officers. Department of Atomic Energy, Northern Region, New Delhi. The work done by the above Department as also by the Departrtent of Geology and Mines, M.P. state etc. stl'll remains unpublished. However, whatever little work done and published by the Geologists of the G.S.I, during field season, 1977-78 and 1981-82; as also by Banerjee (1982); Banerjee, et al. (1982) and Saigal and Banerjee (l987) will be discussed here in detail. The characteristic features of these phosphorites will be discussed separately. Here, the author desires to clear one more important point that the structural features are mostly comimsn in the non-phosphatic and phosphatic rocks of the Bijawar Group though they differ in their lithdlogical and petrological characters. The shales, ironstones and quartz-breccia are not phosphatic in the study area. All phosphorites occur as lensoidal bodies, red phosphatic beds and patches, silty and clayey layers and/bands, muddy-banks, basinal bordering phosphorites, etc. All the phosphorites are ferruginous and show red colouration due to the presence of iron-oxides. These phosphorites, which belong to early to middle Precambrian age, are affected by several tectonic activities, volcanic instrusions, faulting, folding. 54 crushing, brecciation, weathering and erosion, lateritization uplifting and low graderaetamorphism processes . The 'Bijawar Formations• manifest themselves in two outcrops. The larger one between the two extends for a distance of approximately 75 kms. from Mardeora on the west and Gangau village in the east. The other and smaller one, occurring further west of Mardeora falls in the Sonrai area, district Lalitpur (U.P.)» Major phosphorite occurrences are, however, located in the larger patch of outcrops. The ferruginous- argillaceous group of rocks (red-beds) are the host of uranium as well as phosphate in the study area. This group is composed mainly of ferruginous siltstones, shales, mudstones and iron stones. In the lower horizons, the ferruginous siltstones are dominant which laterally and vertically merge gradationally into the other type. This represent an environment, where clastic fine-grained sedimentation was predominant with inter mittent precipitation in the form of ferruginous cherts. These rocks contain phosphate and uranium. The phosphate at places, is recognised as crystallized apatite, whereas, at other places, it is in nodular and concretionary masses as well as layers and thus appear to be syngenetic in origin (personal discussions with Scientific Officers of Department of Atomic Energy at Camp Hirapiir during the months of November-December, 1976). 55 Rajarajan (1978) while discussing the origin of the Bijawars stated that the predominant red colouration and the lithology of the Bijawar rocks indicated that they belong to •Red Bed* facies. Regarding the origin of the red-beds, Twenhofel (1950) says, *As with most sediments, they originally were referred to marine origin but the weight of opinion at the present time refers them to deposition in a continental environ ment which at times has some connection with the sea'. In relation to his field observations, Rajarajan (1978) further addes, 'The absence of evaporites deposits and also of marine fossils, as is notably the case for many parts of the 'Red Beds*, coupled with the presence of sedimentary features seemingly best interpreted of stream formation, hardly permits the postulate of a marine environment for these merits and suggest deposition over flood plains or the subaerial plains of deltas and possibly to some extent over the subaqueous plains of deltas. He concludes, *The most favourable condition for deposition and preservation of colour of red sediments on land areas lies between the extremes of some degree of moderate rainfall and- semi-aridity under relatively high temperature conditions. Deposition need not have been extremely rapid but rapid deposition would have been a favourable factor*. Mathur and Mani (1978) put the phosphate bearing rocks at the top of the Bijawar Group, They mentioned that the phos phorites in the Hirapur area, district Sagar (M.P.), India, occur 56 among the shales, ferruginous breccia and conglomerates which show low grade of metamorphisa at places. These ferruginous and phosphatic rocks of Bijawar Group of rocks were Introduced by them as *Gangau Ferruginous Formations* after village name, Gangau, on the east, some 75 kxns. from Mardeora village (Table-VIII). Later on Banerjee (1982) and Banerjee, et al. (1982) and Saigal and Banerjee (1987) visited the Hlrapur-Mardeora areas# districts Sagar and Chhatarpur (M.P.) and classified the phosphorites into four types on the basis of field observations and stratigraphic positions already given by Mathur and Mani (1978). The four types of phosphorites are a) ferruginous, shaly, laminated phosphorites; b) massively, bedded, highly ferruginous phosphorites; c) brecciated/conglomeratic ferruginous phosphorites and d) veins/pore-filling type remobilised/secondary recrystalli- zation apatite-phosphorites. They put shaly phosphorite type at the lower part of the Gangau Formations of the Bijawar Group. Each of these phosphorites show transition into the other phosphorites type depending upon the degree and intensity of weathering, leaching, recementation, etc. According to Banerjee, et al. (1982) the bedded phos-» phorites originated by quite water precipitation have been remobilised and recrystallised at places during episodes of weathering/leaching. The lower CO2 content in the carbonate- 57 -fluorapatite phase indicated the hidden weathering by which the decarbonation took place. Higher alkalies content indicated the palaeosalinity of the Bijawar basinal sea waters. This also supported the restricted circulation of the sea-waters which was controlled by palaeotopography of the sea. The presence of crandallite in secondary phosphorites further supported the episodes of weathering processes which might have taken during tropical to arid climatic conditions. Widespread ferruginous content in these phosphatic sediments supported the origin in the •Gangau Iron Pormations *. A team of geologists namely, Ali« K.N.; Kumar, B.; and Sonakia/ A. of the G.S.I, had carried out the field investigations of the Bljawars in the Hirapur area, district Sagar (M.P.) during field season, 1981-82. A report of their field investigations was later published by Nath and Mukherjee (1987) of G.S.I, as below :- The investigation led the investigators to establish the succession of the Bijawar lithounits. Further, geological mapping of the Bijawar formations enabled them to locate detached occurrences of brecciated-phosphorites at the contact of ferruginous-shale and to determine the lithologic relation of the phosphorite horizons with respect to the dolomite, shale, ferruginous-breccia, etc. They also demarcated a laminated band of phosphorite trending E-W for about 300 metres with average 58 width of outcrop of about 70 metres. The present author fully agrees with the observations made by Mathur and Manl (1978); Banerjee (1982); Banerjee, et al.(1982); Ali, et al. (1981-82); Nath and Mukherjee (1987) and Saigal and Banerjee (1987) that the Gangau Ferruginous Formation lies at the top of the Bijawar Group. Primarily, the phosphorites are found to be of three types namely, shaley-laminated phosphorites, iron stones-phosphorites and quartz-breccia phosphorites. At places the shaley-phosphorite show a greater intensity of weathering and leaching as a result of which innumerable voids/cavities/porea/ veins, etc. were formed. Later on these open spaces were filled with secondary phosphate and other materials. They are introduced here as secondary phosphorites. The descriptions of these phos phorites are given as follows s- The shaley-laminated phosphorites overlie the non- phosphatic shales and form the lower most bed of Gangau Ferruginous Formations. These phosphorites are thinly laminated and brownish red in colour. Bedding fissility is well developed. Silicification of the rock is a common feature. But at places, these phosphorites directly rest either over the older basement rocks of Bundelkhand Complex or limestones and/dolomites of the Bijawar Group, sericite and some micaceous-minerals with some grains of quartz are their main constituents. Bedding laminations, ripple marks, parallel disposition of flaky minerals, rain drop Imprints, current bedding, grooves. 59 etc. are the common primary structures found In these rocks, some secondary structures like boudins, faults, anticlinal and synclinal folds, mineral-veins and fracture fillings, pebble/boulder like structures, striations, together with minor scale slippages and penecontemporaneous contortions in the rocks are also discernible. At places, the folds are represented by sharp kinks and gentle warps. They are plunging and disharmonic in respect of both axial trends and intensity of folds. The direction and amount of these folds vary from northeast to southeast and from 20*^-40*^ respectively. Panning and curvilinearity of the axial trends of these folds are the common feature. A total of five major shaly-laminated phospho rite bodies were identified in the field. Their approximate strike length and width of outcrc^ vairy from 1 to 7 furlongs to 1/2 to l?/2 furlongs respectively. Occasionally, the phos phorites are feebly metamorphism as indicated by the occurrence of some slates and phyllitic in them (Figure — in pocket, and Table-IX). Ill,2.2.7.secondary Phosphorites : The weathering and leaching of the mineral constituents of the primary phosphorites played a very significant and important role. The intensity and degree of weathering and 60 leaching effects are more conspicuous in the shaley-laminated phosphorites which formed the lower most bed of Gangau Formations according to Mathur and. Mani (1978); Banerjee (1982) and Banerjee et al. (1982). The primary sedimentary structures of the shaley phosphorite have been completely obliterated due to weathering and leaching, but at places the 'reiniform* structures still preserved. In the study area, total at four places, the secondary phosphatisation of the primary shaley-laminated phosphorites were located. Unlike the first type of phosphorite this one is light reddish to greyish white in colour. Rest of the primary and secondary structures are almost same as in the first type (Figure - in pocket and Table-IX). III.2.2.8, Ironstone Phosphorites s The iron concretionary shale, ferruginous quartzite and brecciated chert layers host economic phosphorite deposit, presently being mined by the Madhya Pradesh State Mine Corporatioi (Roday, et al., 1989). They are very fine-grained and their outer surface is comparatively smooth and dark brown in colour. At places, there are some nodules of hematite were seen. Besides, hematite, magnetite, there are some encrustations of goethite and limonite associated with the rocks. The intensity 6t of weathering Is milder in comparison to the shaly-laminated phosphorites. Due to very fine granularity and compactness of this ore, this phosphorite may be called as mudstone or clay- stone. Due to the presence of hematite, magnetite and secondary iron-bearing minerals (goethite, limonite, etc.) these rocks may also be called ironstone phosphorite, sericite, muscovite and quartz are some of the minor constituents. The presence of some primary and secondary sedimentary structures are common as in the case of shaly-laminated phosphorite. Four ironstone/mudstone and claystone phosphorites bodies/beds/patches were identified. The strike length and width of outcrop of these beds varies from 1 to 7 furlongs and 1/2 to 5 furlongs xrespectively. At places, the ironstone phosphorite rest directly over the non-phosphatic shales, ironstones, quartz-breccia and rarely linestones also. Secondary silica veins composed of cherts are common in all the four types of phosphorites (Figure - in pocket and Table-IX). III.2.2.9. Quartz-Breccia-Phosphorites t In the study area, the quartz-brecciated and/brecciated- quartzitic phosphorite is the fourth type. It is also bedded and ferruginous but they are not laminated. A total of nine phos- phatic bodies in this type of rock were identified. This type of phosphatic rock overlies the ironstone-phosphorite but at 62 places it overlies directly the non-phosphatic shales, iron stones and mostly on non-phosphatic quartz-breccia. This brecciated-phosphorite rocks are gradually merged into the host rocks. Their structural characteristics are very similar to these of the associated rock. In other words, these brecciated bands behave as a distinct lithological unit and are omni present in the Bijawar Formations. They have also undergone folding like other lithic units in the study area. As such, they appear to be intraformational sedimentary breccia only. Possibly both types of sedimentary breccia, viz., para- conglomeratic/tilloids and real deforroational ones are also present. The degree and Intensity of %*eathering and leaching in this ore is also milder in comparison to first type of phosphorite. At places, these phosphorites are also feebly metamorphosed (phyllites, phyllonites, etc.). The rocks consist mainly of clasts of subangular to subrounded cherty materials, quarta(which may be derived from quartz-veins/reefs), quartzites, schistose rock fragments and other host rocks of the Bijawar Group. The intergranular spaces of these brecciated- phosphorites are filled with secondary silica, iron-oxides and calcareous materials in the form of matrix. Thus, the matrix of these breccia varies from ferruginous mudstone on one hand to a ferruginous cherty mass on the other. The approximate measured strike length and width of outcrop of these phosphatic 63 bodies varies from 3/4 to 6 furlongs and 1/2 to 3/4 furlong respectively. Rest of the primary and secondary sedimentary structures are almost the same as those found in the first to third types of phosphorites (Figure - in pocket and Table-ix), 64 CHAPTER - IV PETROLOGY, PETROGRAPHY AND PETRO-MINERALOGY Before discussing in detail the petrology, petrography, petro-mineralogy (megascopically and microscopically), scanning electron microscope, chemical composition and X-ray diffraction studies of the Hirapur-Mardeora area, the author will discuss the general petrographic. X-ray diffraction and scanning electron microscopic and chemical composition, nomenclatures of particularly 'phosphate* bearing rocks which are known all over the woiMd and proposed by earlier workers. The general nomenclature of the world phosphorite deposits, based on the petrography, chemical composition, scanning electron microscope and X-ray diffraction studies and given as below. The term •cellophane* applied to many of these mineral complex is probably just a convenient name for several phosphate related minerals. Most common are the 'Phosphates* of calcium, particularly the varieties of apatite such as francolite, dahllite often asso ciated with 'Collophane' (Lacrox, 1910; Schaller, 1912; Rogers, 1922 and 1944; Hendrich, et al., 1932; McConnell, 1950; Bushin- sky, 1955 and Pettijohn, 1984). McConnell (1950) listed 38 phosphate minerals known in rock phosphates, many of wnich are rare. The mineral components of the phosphates are different 65 to study because of their sub-microscopic crystals and admixture studies show that isomorphic replacements are common. Mabie and Hess (1964 and 1974) were nicely discassed in detailed the nomenclatures, classifications, nature of occurrences, optical properties, etc. of the 'phosphate• bearing minerals of the 'Phosphate ores' of United States. The brief descriptions of the above workers are given as below. The 'Collophane* occurs in the form of syngenetic, spherical, oval or ellipsoidal bodies, pellets or nodules or as interstial materials between gangue mineral grains or as structureless massive form. The texture is generally described under three headings - (1) nature of dispersion of pellets - whether compacts, semi-dispersed, dispersed or interstial; (2) nature of pellets - whether incased, nucleated, ovulitic or oolitic and (3) crystalline nature of cellophane - whether isotropic or anisotropic, in the later case whether macro crystalline, microcrystalline or micro-cryptocrystalline. Pelletal 'Cellophane* exhibited both oolitic and ovulitic structures. Pellets were further classified as either simple* or compound, with the former being the most common. Simple pellets usually consisting of a single pellet centre encased by •Collophane*. In some samples pellets with an oolitic structure graded into those with an ovulitic structure. 66 These gradational textures may represent stages in the •diagenesis' of the pellets. As a result of compaction, pellets had often been flattened to take an oval, ellipsoidal or spindle shapes. In a few sample, some pellets have been severely mashed into irregular, ill defined bodies, mashing appears to be most severe in the samples with sand sized quartz, cellophane pellets adjacent to one another were inter locked by shallow to deep sutures. Mabie az3d Hess (1964 and 1974) again define the word •Cellophane* is used as a general term to describe the crypto- crystalline end microcrystalline apatite found in sedimentary phosphorites. It has no specific compositional connotation but it does sioplv a chemical origin. They studied around 150 crypto-crystalline varieties of different 'phosphate* bearing minerals by X-ray analysis. The chief commercial mineral is apatite (Ca2(?0^)2 Ca(P, CI) which occurs in comparatively pure deposits of rock phosphate, or phosphorite, which forms the bulk of the material entering the trade is composed mainly of apatite ii: finely crystalline or amorphous conditions and may contain varying quantities of aluminium and iron phosphates and also earthy impurities including clay, silica, lime and other minerals - (1) spherulitic •Cellophane* was commonly associated with buggy areas. Chains of microcrystallines Cellophane Spherulitic occasionally occurred as veinlets in 67 isotropic cellophane. During the study of Hirapur-Mardeora phosphorites, the author has studied the all world phosphate deposits and classified the 'phosphate' bearing minerals particularly on the basis of 'C^hfinical composition* into total 17 major groups namely, phosphates of uranium, rare- earths, aluminium, iron, calcium, zinc, magnesium, manganese, lead, vanadium, alkalies, ammonium, copper, beryllium, lithium, strontium, chromium, etc. These 17 major groups of phosphates are having total 197 varieties of 'Phosphates' minerals (Table-X) The essential mineralogical constitutents of the 'phosphate' bearing rocks or phosphorites are difficult to study because of the predominance of cryptocrystalline and amorphous states of minerals associated with fine grained impurities and numerous isomorphous replacements (Carozzi, 1960), Altschuler, et al. (1952); McKelvey (1953) and Gul- brandsen, et al. (1966) favoured the more specific composi tional term 'carbonate-floiirapatite' or .apatite, rather than collophane. The non-pelletal phosphorites are composed pre dominantly of a fine-grained structureless 'cellophane' groundmass with siliceous, calcareous or ferruginous inclusions. Under high magnification, it is evident that the collophane groundmass is composed of a fibrous mass of fine apatite needless; in some instances, the needles appeared to be randomly oriented but in other cases, the needles are arranged 6S in a radiating form giving the rock is a microspherulitic habit (Deer, et al., 1962 and Cook, 1972). The Mussoorie phosphorites are composed essentially of carbonate-fluorapatite - Ca^(PO^)^{F, CI, OH, CO3) parti cularly 'collophane* (amorphous and colloidal) and francolite (a crystalline carbonate-apatite). Microscopic examination of thin sections also revealed the mineral assemblage-collophane (rock phosphate), carbonates (calcite and dolomite), silica and silicates (chert, quartz and mica), pyrite along with traces of gypsum, barite and magnetite. The phosphatic material occurs as an extremely fine and irregular granules cemented by calcareous and siliceous materials. 'Collophane' is a massive form of apatite, is seen as bands associated with chert and shale as a rim to rounded chert pebbles as fracture-fillings in dolomite, pebbles and pellets of phosphorites are also seen cemented by carbonate (Rao, et al., 1974 and Dubey and Partha- sarthy, 1975). Mineralogically, the two main phosphatic mineral in phosphorites are carbonate-apatite-'dahllite• (Cac (PO., CO^, OH3) F) and 'francolite' (Ca5(P0^, CO^* OH)^ OH); these two occur together with cryptocrystalline phase known as 'collophane* (Sankaran, et al., 1980). All the phosphate minerals were iden tified only by a petrographic microscope. The following termi nology is used - prigmatic apatite; cryptocrystalline, brown. 69 isotropic apatite (Cf. collophane) and crystalline colourless, commonly fibrous apatite (Twenhofei, 1950; Pettijohn^ 1975 and Trompette, et al., 1980), The chief phosphate-minerals aire 'collophane*, a crypto- crystalline, carbonate-fluorapatite and its microcrystalline fibrous variety francolite. in some phosphatic rocks, however, aluminium or calcium-aluminium phosphates (wavellite or cranda- llite) may be the main phosphate mineral-s. The later characterise the leached zone deposit of Florida, Senegal and Nigeria (Emigh, 1958; Espenshade and Spencer, 1963; Dar, 1970; Cook, 1972; Parker and Siesser, 1972). By far the largest pari: of the apatite in the phosphorites occurs as •Cellophane' (the name of collophane is here applied to the varieties of apatite consisting of crystallines of submicroscopic size). Most of the collophane of the sediments of the Bettle Creek Formation occurs in parti culate form as pellets and minor fossil fragments. However, some of the collophane, particularly in the basal section of the Creek phosphorites, occurs as colloform mudstone beds or as cements binding breccia fragments or clastic constituents (Russell and Trueman, 1971; Chakrabati, et al., 1973; Fuller, 1979; Al-Bassam, et al., 1983 and Boyle, 1984). The characteristic minerals of phosphatic sediments are collophane which is isotropic and dahllite which is optically similar to apatite. The phosphatic materials appears in a number of forms which may be briefly summarised as follows s- 70 (1) Bones, phosphatic tests, excreta; (2) Relatively purs phosphate with fine scale banding; (3) Nodules of collcrphane; (4) Pseudo^jnaorphs of calcite shells, oolites etc; (5) Collo- phane cements of sandstone. The cellophane is a coinplex phos phate of carbonate, chloride, fluoride etc. of calcium. It is massive in nature and occurs as colloform, oolitic etc., often containing organic remains. Optically, it is isotropic or weakly showing birefringent due to strain and index above Canada balsam (McConnell, 1950; Banerjee, et al., 1980). The phosphorite bands consisting of poorly birefringent 'Cellophane • are also partly recrystallised into fluffy form of dahllite. The bands of fibrous Chalcedony are intimately associated -with bushy tuffs of a fibrous mineral oriented at right angles to the chalcedony fiberes. The fiberes show low order interference colour, straight extinction, moderate relief, uniaxial, negative character and appeared to be dahllite and one length fast (Bhattacharya and Sengupta, 1984). Classification and nomenclature of apatite is based on the presence of chloride, fluoride, carbonate, hydroxyl, oxygen groups etc. An apatite having chloride molecules in its structure is known as chloroapatite (Ca.QCl2(P0^)g); fluoride as fluor- apatite (Ca^^QFj (PO^)g); carbonate as carbonate-apatite (Ca2^0^3^^^4^6^' ^y^^^o^Y^^ol as hydroxyl-apatite (Caj^QCOH). (PO. )g ) and oxygen as oxy-apatite (Ca]L0^^^4^6^ (Krishnan, 1942; Parker, 1971 and Pettijohn, 1975). 71 The technical discussions was held along with Khan (1979), Scientific Officer, Department of Atomic Energy at Hyderabad (A*P*}« India, who was studied the phosphorites samples of Hirapur-Mardeora area during field season, 1975-76 and 1976-77 under the petrological microscope. He told that petrographically the apatite is primary (non and/less weathered) phosphorites occur as *Collophane» and in secondary phosphorite samples it looks like a dahllite in the form of thin veinlets etc. In some phosphorites, the 'Collophane* occurs as granular, rounded pellets of an amorphous form giving the rock a pseudoolitic character. a.rt The vesicular varieties^altered products into which enter phosphates of iron and alumina. Various phosphatic nodules found in different state may either be carpolite in the strict sense or be composed of *Collophane* calcium-carbonate and mineral matters. These phosphates are essentially varieties of calcium phosphate with or without fluorine, calcium carbonate, iron-phosphate, aluminium phosphate etc. Among specific minerals may be mentioned 'Collophane, dahllite, francolite'. Associated impurities include quartz, calcite, dolomite, chert, pyrite, marcasite, glauconite, etc, (Milner, 1950; Teodorovich, 1961 and 1981; Fletcher, 1981 and Tiwari and Qureshi, 1985). As pointed out by Lehr, et al. (1968), the crystal shape, packing effects and strain influence the X-ray determination of crystallite size, therefore some of the apatite crystallites in 72 the microsphorite were also examined by Scanning Electjron Micro scope (SEM), Polished as well as fresh fractured rough surfaces of phosphorites were studied under a Camscan Scanning Electron Microscope not only to determine the textural variation in the microsphorite but also photograph the apatite crystallites in order to confirm the size measurements resulting from the X^ray method. The apatite crystallites occur adjacent to flat prismatic carbonate grains and the crystallite size of the apatite is on the order of 0.1 to 0.3 /ton which is quite compatible with the results of the X-ray diffraction measurements. Most of the apatite crystallites are equant in shape while some show a Oaxis elonga- tion. In recrystallized stromatolitic phosphate layers, apatite crystallites occur as large (1.4 to 7/Cm) prismatic grains with a shorter a-axis. The SEM examination clearly shows that the phosphorites described* here were formed 'authigenic* by chemical precipitation (Banerjee, et al., 1980), Altschuler, et al. (1953) gave 9.413 A° for hydroxiapatite; 9.386 A*' for fluorapatite and 9.344 A° for carbonate-fluorapatite, McConnell (1938, and 1956) gave for francolite, 9.34 A°; the carbonate-fluorapatite of M©ntel, 9.36 A and synthetic fluora patite, 9.37 A*'. For other authors (Deer, et al., 1963) the average values are 9.41 A*^ for hydroxiapatite; 9.34 A° for carbonate-fluorapatite and only 9.35 A° for fluorapatite. 73 For average apatite samples from Jhamarkotra the cell- dimensions are ao= 9.36 to 9.368 and Co = 6.888; for Matopn samples, a^ * 9.369 to 9.371 and Co « 6.880; for Kanpur samples, a^ = 9,357 to 9.360 and Co = 6.90 and for Hirapur-Bassia samples a « 9.296 to 9.335 and Co = 6.851 to 6.890, An average Cumbum sedimentary apatite has a = 9.34 A° and Co » 6.87 A**, cell dimension (Banerjee, et al./ 1980; Srivastava and Banerjee, 1986 and Banerjee and Saigal, 1988). The unit-cell dimensions values for the Georgia Basin phosphorites show a considerable spread, as is a ranging from 9.3424 A° to 9.3596 A° and Co from 6.8758 A° to 6.8944 A°. The cell-dimensions, A and Co are dependent on the amount of CO, and F substituted in the carbonate-fluorapatite (Smith and Lehr, 1966 and McClellan and Lehr (1969). Banerjee, et al. (1980) said that the variations in a cell-dimensions particularly in the 2 —3 apatite due to substitution of (CO,)' for (PO,)" which resulted in the formation of carbonate-fluorapatite with slightly more than 2% F in their structure. This study conform the observation of Trautz (I960) and LeGeros, et al. (1967) who found that carbonate substituted apatites have a shorter a axis and somewhat longer Co axis compared to carbonate free but F and OH rich apatites. Thus,the carbonate is apparently located within the apatite structure (McClellan and Lehr, 1969). It is interesting to note that 'a ' length increases unproportionally where C0„ falls lower than 1% (llyuin and Bliskovsky, 1984). 74 The apatite is crystalline fluor-carbonateapatite with well defined diffraction peaks and contain more than 4% CO- (Gulbrandsen, 1970 and Lucas, 1984). X-ray diffraction study indicated that carbonate-fluorapatite is the major apatite phase in all four types of phosphorites of Hirapur-Bassia area. In secondary phosphate the pattern of peaks comparable to crandallite- an aluminous-calcium-phosphate, which seems to have formed by variable substitutions in the apatite structure along the apatite-* crandallite-millisite weathering series. The XRD patterns for roost Precarabrian Indian phosphorites show sharp, well defined diffraction lines suggesting a.high degree of crystallinity for these apatites the other major mineral components of the phos phorites, such as quartz, calcite, dolomite, side rite, goethite and occasional illite, montomorillonite are identifiable in the X-ray diffraction pattern of the bulk phosphorite sanples. The study area, particularly in the primary phosphorites, there is still controversy regarding the nomenclature of apatite varieties, whether the apatite is cellophane and/francolite and/ dahllite but in secondary phosphorite the apatite mineral variety is crandallite (calcium-aluminium phosphate) which has been confirmed by X-ray diffraction and scanning electron tnicroscopic studies. ThusJ on the basis of different studies of earlier workers all over the world phosphorite deposits as discussed above, the author will take apatitic phase (carbonate-fluorapatite) as 75 •Collophane' in the primary (non-weathered) phosphorites and •Crandallite' in secondary (weathered) phosphorites samples. In few saaples of primary phosphorites, thin veinlets of Collophane also seen and this mineral and/phase author will call as •recrystallized collophane*, etc. On the other hand, in megascopic and miqroscopic study of Bundelkhand Complex (basement of Bijawar Group Rocks); Bijawar Group Rocks (host rocks of phosphorites) and Lower Vindhyan Group Rocks (overlying rocks of phosphorites), the author will take •apatite* as a general term known all over the. globe. Now the author will discuss systematically in detail the megascopic, microscopic, scanning electron microscopic, and X-ray diffraction studies including chemical compositions of all the rock types of the Hirapur-Mardeora areas as follows - IV. 1. BIJAWAR GROUP (EARLY TO MIDDLE PRECAMBRIAN ) : IV.1.1 Megascopic and Microscopic Studies : A detailed account of the petrography and petromineralogy of the phosphate bearing rocks of Gangau Ferruginuous Formations is given in addition to the megascopic and microscopic characters of the host rocks of the phosphorites. The host rocks of the phosphorites of Bijawar Group are quartzites, limestones, dolomitic-limestones, shales, ironstones, quartz-breccia, etc. 76 Among these rocks, some are of heterogeneous association like quartzitic-limestones, siliceous-dolomitic-limestones, ferru ginous, shaly quartzites, etc. The main •phosphate' bearing rocks are phosphatic shales, ironstones and quartz-breccia. IV. 1.1.1. Quairtzites s Megascopic Characters s Quartzites are white to reddish white in colour. The predominant mineral in the rock is quartz that occurs in granular forro. Pew specimen show xenoblastic texture having foreign rock fragments of feldspars. Quartz is anhedral,lts grain-size fine to medium. These rocks are firm, hard and consolidated after being cemented by secondary solutions. There are several thin laminations of secondary silica and iron-oxide seen at the outer margins of tire rock. Microscopic Characters : The rock exhibits crystalloblestic and granuloblastic textures. Occasionally, idioblastic texture is also developed in the rock. Quartz is mostly colourless or light yellow in colour. There are some secondary microveir.s of cherts and chalcedony, sericite composed mostly of minerals mica-flakes of muscovite. There are few grains of feldspars that are visible 77 in the fine groundmass of quartz. Grains of opaque are ubiquitous. A few fine grains of limonite showing blood-red colour have also been identified. They usually occur as inclusions in the ground- mass of quartz. Some iron-oxide occasionally# the cementing material of the quartzite is made up of red iron oxides. „ "S®" IV. 1.1.2. Limestones s AocNo. "^>^ Megascopic Characters s ^(^B^v ^ I J J — x'^a.^^ .-'i^ In hand specimen, the colour of limestones vary from light grey to white, pale-greyish to much darker colours. They are mostly fine to medium grained, hard and compact, Calcxte is cryptocrystalline in form and have very minor silicified and calcite veins. Occasionally, secondary siliceous, calcareous and ferruginous micro-veins in the limestones. The ferruginous secondary fillings are more or less obliquely disposed with respect to the siliceous and calcareous veins. There are some pseudomorph of calcite aftr quartz, Ihere are two generations of calcite present in these rocks, the first one is of light pale grey and the second one is white in colour which occur as thin laminated veins. Microscopic Characters : The limestones are mostly epiclastic, oolitic or crys talline. The grains of calcite is medium to fine, some thin 78 sections show the occurrence of coarse grains of calcite together with some subhedral grains of dolomites. The carbonate minerals are subangular to angular in shape. The rocks are well to moderately sorted and sabmature to mature in nature. Inter- granular contacts are floated long and tangential. The framework is normal to condensed. Calcite is subeqaidimensional and mono- crystalline. Occasionally, silica and iron oxides also constitute the cementing material. Dolomite occurs interwoven with the calcite forming a mosaics structure. Dolomitic grains which are usually euhedral are subequldimensional and monocrystalline. Cellophanes being amorphous are very fine-grained. Often, cellophanes made up the groundmass of calcite which is almost monocrystalline and inequidimensional. Sometimes, quartz occurs as a secondary vein mineral* IV.1.1.3. Oolomitic Limestones t Megascopic Characters t In hand specimens, the dolomitic-limestones appear earthy, and exhibit dark blue to light bluish, pale-grey and light red colour. They are massive, hard, compact and thr grain size is fine to coarse. Occasionally, there are minor veins of iron oxides and carbonates cutting across the rocks. Calcite grains are partly replaced by dolomitic grains. The presence of small pits 79 and cavities on the surface of the rocks are supposed to have originated on account of ground water reactions over the outcrops. Microscopic Characters : The dolomitic limestone show epiclastic, crystalline and oolitic textures. Calcite is the predominating mineral which is anhedral to subhedral in shape. Often there are some fine aggregations of calcite and dolc»nite. Usually the crystals of calcite are elongated and have floated contacts with each other. Few thin sections show disrupted grains of calcite and dolomite, which are anhedral and subhedral and occasionally euhedral in shape. There are two sites of cleavage %7hich intersect at more than 65 . The crystals of calcite are colourless to pale-grey in colour and show one set of cleavage with symmetrical extinc tion. The grains show slight alteration at a few places. There are calcareous and ferruginous contents present as cementing materials along the grain boundaries of calcite. Dolomite is generally cryptocrystalline and pale-grey in colour. It is also subequidimensional having one set of cleavage and symmetrical extinction extinction like that of calcite. Opaque grains of hematite also seen randomly. The hexagons and cryptocrystalline cellophane occur in the groundmass of calcite and dolomite. Cellophanes are massive, brown to grey in colour. 80 IV.1.1.4. Quartzitic - Limestones : Megascopic Characters s As the name indicates, it is a combination of two different rock units. This rock sample was collected from the contact of quartzite with limestone both of which occur at the base of the Bijawar Group. The quartzite is composed mostly of quartz and the limestone of calcite. In hand specimen, both quartz and calcite grains are clearly discernible, it is yellowish, white to grey in colour and shows granulose texture. Sedimentary structures like concordant laminations and crossed fractures are observed in calcite bearing portion but rarely seen in quartzose portion of this unit. Microscopic Characters s In thin sections, the quartzitic-limestones reveal epi- clastic, interclastic and crystalline textures. The fine grained Cclcite predominates. The fine grained calcite intermixed with fine to medium grained quartz form a mosaic structure. Both Calcite and quartz are sub-rounded to angular in shape and they are moderate to poorly sorted and submature in stage. The grain contact of calcite with quartz are floated and tangential. Celcite is colourless to light grey in colour. It is equi- dimensional and monocrystalline in form. It is composed of 8t one set of cleavage planes with symmetrical extinction. The cementing materials are generally siliceous or ferruginous. Quartz grains which are medium to coarse grained are colourless or light yellow in colour. It is subequidimensional and poly- cirystalline in form. IV,1.1.5. Quartzitic Shales s Megascopic Characters : The rocks are hard and compact and usually coloured faintly reddish to red. They are almost fine to medium grained. Quartz grains are generally anhedral and granular in form. Some hand specimen have concordant laminations and workable iroa- oxide content as cementing material. Microscopic Characters s In thin sections, quartzites are reddish-brown and dark red in colour. They show epiclastic crystalline and oolitic texture due to cellophane. The quartz grains are mostly fine to medium grained and anhedral to subhedral in shape. These rocks are moderately sorted and submature in stage. The quartz grains have sutured and tangential grain contact with condensed to normal framework. Quartz is the most dominating constituent. It is brown, red and reddish-black in colour. It is equi- 82 dimensional and having polycrystalline phases. Hematite, limonite and collophane occur as inclusions in quartz. There are also some veins of quartz in the fine groundmass. Other silica minerals namely, chalcedony (as fibrous grains) and opal occur here and there. Collophane occurs as colloform forming oolitic textures in the fine groundmass of quartz. It is light brovm in colour, due to red colouration by iron oxides. In some thin sections, collophane occurs in euhedral, hexagonal and fibrous forms. IV.1.1.6. Shales s Megascopic Characters : In hand specimens, the shales are brown, reddish-brown and dark black in colour. They are fine to medium grained and became hard and compacted due to cementation by ferruginous and siliceous materials. They show primary bedding, laminations and current beddings. Some of the shales are cross-bedded with small cracks and minor fractures. These shales are actually highly ferruginous throughout the area due to their close association with ironstones and iron-ores beds. Microscopic Characters r In thin sections, the shales are brown, pale-grey and reddish in colour. Sometimes, collophane is associated with the 83 shales besides some quartz. The minerals are mostly subangular to angular in shape. The clay minerals are arranged parallel to bedding planes. Often the thin laminations of clay minerals aire bent around some coarse quartz grains. The rocks are stained by universally^iron oxides throughout thin sections. Minute particles of hematite, limonite, magnetite/ cellophane, sericite, chlorite, feldspars (albite) and some mica-flakes (biotite and muscovite) constitute the groundmass of the rock. Kaollnite is the most predominent clay mineral. Kaolinite is pale-yellow in colour. IV.1.1.7. Ironstones and Iron Ores J Megascopic Characters s ' In hand specimens, the ironstones sometimes known as black shales which on geochemical analysis revealed very high content of iron. The ironstones are dark red to or steel grey in colour. Grain size of these rocks varies from fine to medium Grains are mostly euhedral in shape and granular to sub-angular in form. They show metallic lustre, conchoidal and uneven fractures. Ironstones are very hard, compacted. Microscopic Characters : In thin sections, the ironstones are dark in colour. They are mostly fine grained and composed of granular forms of u iron bearing minerals. Hematite is the most dominating consti tuent and its grains are variable in size. They are mostly anhedral to subrounded in shape. The ironstones show epiclastic, oolitic and crystalline textures. Cellophane grains occur in the fine groundraass of the hematite. There are few fine grained crystals of quartz that occur in the groundmass of hematite. Its grains are anhedral and brown in colour. Quartz and cello phane grains occur in the groundmass in all the thin sections. IV. 1.1.8. Quartz-Breccia s Megascopic Characters s The rock is composed of essentially innumerable angular fragments of quartz embedded in a groundmass of iron oxides and secondary silica. In hand specimen, quartz-breccia is reddish- brown in colour. The fragments of range in size from 4 to 12 cm in size. The rock is hard and compact. Microscopic Characters s In thin sections, the quartz-breccia is composed of angular fragments of quartzite. These fragments are cemented by jasper. They show epiclastic and cataclastic textures and are fine to coarse grained. Siliceous and ferruginous materials occupy the fracture spaces generated through brecciation. 85 The iron stained quartz grains consists of fine grained cellophane Quartz is colourless and anhedral in shape with low relief and subguidimensional grains. Some iron oxides also occur in the groundmass. The presence of some limonite and collophane was also recorded from the groundmass. IV.1.1.9. Shale Phosphorite x Megascopic Characters : The common sedimentary structures in all the four types of phosphorites are primary bedding, laminations, ripple marks, rain drop imprints, current beddings, grooves* fracture fillings, pebble/boulder like structures, striations, boudins, minor scale slippages, penecontemporaneous contortions, etc. are the other structures. The shale-phosphorites are brown, reddish-brown to dark black in colour. They are fine to medium grained and have became hard. They are thinly laminated used hence they may be called laminated shale-phosphorite. They are actually highly ferruginous throughout in the area due to their close contact and association with iron-ores and ironstone beds. The mineral constitutents which can be recognised are mainly sericite and some micaceous mineral alongwith some grains of quartz. 86 Microscopic Characters : In thin section, the shales appear brown, pale-grey and reddish in colour, since the shales have the highest concentra tions of phosphatic material and may be called as phosphatic- shales or shale-phosphorites. They show epiclastic, crystalline collophane and oolitic textures. The"colloformals arranged in radiating form. The collophane, quartz, mica grains are mostly subangular to angular in shape and moderate to poorly sorted. The rocks are immature in stage and grain contacts are embedded, tangential and floated. The clay minerals are arranged parallel to beddings with occasion large grains of quartz. Quartz is the most dominating mineral in the shales. It is stained by the red ferruginous material. The mineral is anhedral and brown to reddish-brown in colour. The cellophane, hematite, magnetite, limonite, chlorite and sericite minerals occur in the groundmass. Iron-oxides occur as cementing material. collophane Occasionally^occurs in hexagonal shape. The collophane is also seen as pelletal form, fine grained spicules which are arranged in radiating form. They are finely crystalline, interstial and amorphous. Hematite occurs as very fine graiiBd disseminations. Limonite is also associated with the fine grained groundmass of quartz. There are a few grains of magnetite also presnet. There are some remnants of feldspars. Albite is identified by its typical albite twinning. Among 'clay* minerals the presence of kaolinite is identified. 87 IV.1.1.10, Secondary Phosphorites : Megascopic Characters : As the author has already mentioned that the intensity of weathering and leaching are greater in the first type of ore association, namely, ghale-phosphorite as compared to ironstone and quartz-brecdiated-phosphorites. Due to weathering and/leaching by ground water circulation, etc. some voids and/ cavities were formed at places. Subsequently, these cavities were filled by phoaphatic, ferruginous and siliceous materials. This ore is white to light brown in colour. It is also hard, firm and compact in nature. This rock seems to be devoid of any primary sedimentary structure and it is thought that the primary sedimentary structures haVe been destroyed by remobilization and recrystallization processes. Some relict sedimentary features like ovulitic texture and mosaics and the presence of framboidal iron-oxide in a very fine grained matrix are recognisable. In some hand specimens the 'jreiniform* structures are also identified, Microscopic Sediments t In thin sections, the ore show we11-developed fissility with criss-cross fractured. These fractures contain lath shaped crandallite grains. The g^ngue minerals are sericite, tiny mica- flakes and a few grains oi quartz. Sometimes, the proportion of quartz grains increases. The ore, which is slightly metamorphosed 88 shows lepldioblastic texture. In some thin sections the recrys- tallization of new minerals and destruction of primary sedimentary structures is also discernible. Only relict type of pelletal texture in the form of ovular crandallite, mosaics and the framboidal iron-oxides having fine grained matrix is also noticed. The minerals in these rocks are chiefly equlgranular with anhedral grains of crandallite and intergranular sericite or muscovite and iron-oxide (mostly goethite and hematite). IV.1,1.11. Ironstones Phosphorites : Megascopic Characters s In hand specimens/ the ironstones sometimes recalled as a black shales which on geochemical analysis reveal higher concentration of phosphate and iron is called highly ferruginous and phosphatic shale or ironstone phosphorite in the present study area. This ore is dark red or steel grey in colour. It is very fine grained, compact and hard. In some hand specimens, the discontinuous thin fine laminations were seen. At places, the intensity of weathering and leaching is milder than the first type of phosphorite. Nodular stiructure were also seen here and there. 89 Microscopic Characters : In thin sections, the highly phosphatlc ironstones consist predominantly of hematite, goethite and quartz with rare grains of muscovlte and serlcite. The rock is wholly crypto- to micro- crystalline and its cementing material is iron and phosphorus. Collophane generally occur as oolitic, ovulltic to nodular in form. Occasionally/ there are rare occurrences of recrystallized thin veinlets of collophane and/crandallite. Association of limonite, ilmenite, iron-oxide and a few grains of rutile in the groundmass of hematite and goethite was also noticed. IV.1.1,12, Quartz-Breccia-Phosphorites : Megascopic Characters s In hand specimens, this ore is brownish in colour, hard and fine to medium grained. There is no indication of bedding lamination in the rock. The angular to subrounded fragments of chert and quartzite, some schistose metamorphic compose the groundmass of the rock. There are some thin minor veins of chert and iron oxides. The brecciated and conglomeratic structures are common in all the samples. There is little evidence of weathering and leaching of the ore. 90 Microscopic Characters s In thin sections, the rock contains angular to subrounded grains of cherty quartz, quartzites and some schistose rocks. The cherty portion in the slide is making ovulitic to nodular, oolitic or pisolitic type of grain arrangement. The brecciated portions in the rock is filled with phosphatic and iron-oxide materials. IV.1.2. Scanning Electron Microscopic (SEM) Study of Phosphorites Following the observation made by Lehr, et al. (1968) that the crystal shape and its packing effects and strain influence the X-ray determinations of crystallite size, an attempt has been made to examine some of the apatite crystallites in the microsphorite from the study area by Scanning Electron Microscope. Polished as well as fresh fractured rough surfaces of phosphorite were studied under SEM. The detailed descriptions of the photomicrographs of the phosphorites are given as below :- IV.1.2.1. Shale Phosphorites : The collophane pellets are angular to sub-angular in shape and show initial stage of weathering (whitish). Collophane 91 grains are occasionally very fine to medium grained (crypto- to microcrystalline sizes) and embedded in a groundmass of ferruginous minerals (black colour) alongwith other gangue minerals like fine grained quartz, chlorite, sericite and clay minerals. The criss-cross fracture fillings by ferruginous, siliceous and phosphatic solutions are ubiquitous. Occasionally, there are few euhedral hexagons of apatitic (cellophane) which are embedded and surrounded by larger grains of cellophane pellets. The crypto- to microcrystalline cellophane granules sometimes make pseudo-rings and aggregations (PlatejI-A). In this photomicrograph, the cellophanes appear very fine to coarse grained. They are angular to subangular and lath shaped (whitish). The fine grained cellophane grains show microlaminations and ring like structures. The cellophanes which are amorphous, show interstitial textures in a groundmass of ferruginous materials (black) and were associated with gangue minerals like fine grained quartz (whitish), clay minerals (black), etc. The dark coloured iron-oxides are pervasive in thin sections (Plate s 1-B). IV.1.2,2. secondary Phosphorites t This photomicrograph shows the recrystalllzation of phosphate minerals to form crandallite (aluminous phosphate). The crandallites (white) appear crypto- to microcrystalline; 92 elongated and lath shaped; and angular to subangular and sub- rounded in shape. The mineral showing intergrowths towards the cavities/voids which are filled by ferruginous (black) and phosphatic materials that appear as a cementing material* Occasionally* the pseudo-microlaminations and ring like structures are still presezrved after weathering and leaching of primary- shale phosphorites. The ferruginous minerals may be hematite, magnetite, goethite, limonite and iron-oxides associated with fine grained clay and quartz forming gangue minerals. Sometimes, the crandallite also occurs in massive, ovulitic to oolitic and disseminated forms. Twinned crystals of crandallite also seen in this photomicrographs (Plate : II-C). At the centre of this photomicrograph, the filling materials appear to be one cavity filled by ferruginous, siliceous and phosphatic. The secondary phosphate mineral like crandallite (white) shows a progressive growth towards the border of cavity. The mineral occurs in the form of crypto- to micro- « crystalline, granular, amorphous, lath, disseminations and sub- angular to subrounded grains. The fine grained amorphous pellets occur as primary laminations. The gangue minerals being very fine grained, are quartz, ferruginous and clay minerals and which aire mostly confined to the groundmass in which the crandallite grains are embedded. The ring like structure of the fine to medium grained pellets is displayed in the photomicrograph. These all above features of the rock supported remobilization and re- precipitation of the phosphatic and Its associated minerals (Plate i II-.D). 93 IV.1,2.3. Ironstone Phosphorites s In the photomicrograph of ironstone or highly ferrugi nous shaly-phosphorites, collophane which is crypto- to micro- crystalline appear concretionary. These fine grained collophane (white) pellets show discontinuous/ thin, microlaminations. The mineral is granular, massive, amorphous, spicular, ovulitic to oolitic in shape. Fine grained spicules of collophane are making ring like structures. Quartz is also very fine grained. The dark coloured ferruginous and clay groundmass is pervasive in which collophane is embedded. The dark-coloured fracture fillings also clearly seen in the middle as well as at the bottom of the photomicrograph (Plate s III-E)* In this photomicrograph the collophane pellets appears micro to macrocrystalline. These fine grained collophane makes discontinuous ring like structures. The bigger pellets of collophane are elongated, twinned, lath shaped, angular to subangular and subrounded in shape. The collophane pellets are amorphous, spicular, colloform and hexagonal in shape. Pew bigger pellets show intergrowth and/recrystallization. These light coloured cellophanes are embedded in the fine grained groundmass of quartz (white), clay and black coloured iron bearing minerals (Plate 5 III-P). 94 In this photomicrograph, the cellophanes (white) are mostly crypto- to mlcrocrystalline in nature which are embedded in the huge groundmass of black iron bearing minerals. The collophanes are granular, amorphous^spicular, ovulitic, disse minated and weak thin microlaminations in shape. At places, the fine grained spicules of collophanes are making pseudo-ring like structures. The very fine grained quartz (white) grains and clay minerals are also seen as gangue minerals (Plate s IV-G). In this photomicrograph, the cellophane is medium to coarse grained though some fine grained spicules of cellophane are rarely present. At the centre, needle shaped (white) recrys- tallized cellophane and/crandallite is also seen. The cellophanes are pelletal, lath shaped and disseminated. These light coloured cellophane is embedded in a dark ferruginous and clayey groundmass (Plate : IV-H). IV.1.2,4. Quartz-Brecciated Phosphorites : The photomicrograph of this type of phosphorite subrounded (white) of quartzite and angular fragments of elder schistose rock (whitish). The darker and dirty whitish coloured materials cemented the brecciated and conglomeratic fragments of quartzites. The groundmass is ferruginous, phosphatic or siliceous. The collophanes are crypto- to mlcrocrystalline, macrocrystalline 95 angular to subangular^ massive, fragmented^ pelletal/ spicules, lath-shaped, granular, etc. The"dark coloured and subrounded to rounded shaped hematitic and magnetite grains occupy the inter spaces of the brecclated fragments of the quartzites and schistose rocks. These dark coloured magnetite grains are fine to coarse grained. The phosphatic minerals are embedded in the fragmented brecciated rock masses, clay and ferruginous contents (Plate : V-I). In this photomicrograph, the broken angular fragments of quartzites, schistose rocks (whitish) are clearly pervasive. The cellophane (white) are crypto- to microcrystalline, mega- crystalline, angular, amorphous, pelletal, spicular, ovulitic to oolitic, nodular, pseudo-oolitic, fragmental, etc. The fine spicules of cellophanes made very thin discontinuous ring like structures. Some cellophane pellets are lath-sahped v/ith thin veinliBts of crandallite and show growth towards the interspaces of brecciated rock. Pew dark coloured and subrounded to rounded magnetite grains are also among the rock fragments. The dark coloured ferruginous and clay minerals compose the groundmass in which some phosphate minerals are embedded. No laminations were seen in this type of ore (Plate j V-J). IV.1.3. X-ltay Diffraction (XRD) Study of phosphorites : A Phillips X-ray diffractometer with Cu-I^ radiation and nickel filter incorporating a focusing monochromometer was used 96 for analysing the samples. The samples were treated with Silver man Solution for the removal of free carbonates and a purer fraction of apatite concentrate was obtained. The only remaining contaminant was silt-sized quartz. Those samples were scanned by an X-ray diffractometer between 25° to 55° 2^ for measurements of differences in the 2^ values for (004) and (410) hkl indices (Rooney and Kerr, 1969; Banerjee, et al., 1980 and 1982). The lattice parameters were calculated from the observed diffraction patterns and by referring to hexagonal axes with the equation - a° =./l.3333 d^ (h^ + k^ + hk) for (210), (310), (320) and (410) planes and C° = 1 d for (004) and (002) planes. The lattice dimensions of apatitic minerals values are comparable to crandallite in secondary phosphorites (ASTM file No. 16-162) - an aluminous phosphate which seen to have formed by variable substitutions in the apatite structure along the apatite- crandallite-millisite weathering series.(Srivastava and Banerjee, 1981 and Banerjee, et al., 1982). The primary phosphorites (shales, ironstones and quartz- breccia) and secondary (void/cavity/pore/vein/fissure filling types) phosphorite samples were powdered in an agate mortar and sifeved through ASTM sieve sets. The sand sized (200 mesh) and clay sized (-2 00 mesh) fractions are powdered and collected separately. 97 O *-> u ^j O*J rH 5 J- LL t M ^ oo o • ri "=<: m "O J- f* u N •>J rr, • c o rrtj o 3 «J «.(.H' ^-^ 3 c —1 S M «« — V4 > a o 1 o 1 " m (1) D- U-\ 1 4-> c ro fH 10 ITN . c < a. O '•n o o ^^ L- r»"•> ^ p. J/J 0) ^ O CO ir O --< O e TJ ff• XRD study was carried out on the bulk samples of silt sized (coarse to medium) fractions of primary and secondary phosphorite separately but the clay fractions (fine) drawn from both the types of phosphorites are mixed together for XRD study. The sand sized fractions of primary phosphorites were kept chart on 1^ interval angle from 24^ to 54 and the carbonate-fluor- apatite phase comes in between 26.00° to 53.45 for a and for Co, it is, 53.32°. The intensity for a^ is 5.23 to 100.00 and Co is 22.50 only. The d A*^ for a^ varies from 1.71 to 3.43 and for Co, 1.72 only. The calculated lattice parameters of carbonate fluorapatite phase (hkl) for a^ are (210), (300), (310^, (400), (203), (410) and for Co is 004. The lattice cell dimensions of these carbonate-fluorapatite parameters for a varies from 9.31 to 9.36 (9.31, 9.34, 9.35, 9.34, 9.32, 9.31 and 9.36) and for Co, 6.880 only. On the other hand, for quartz, the angle varies from 26.6° to 32.30° and ^he intensity from 45 to 100 only. The lattice parameters of quartz (hkl) are (112 and 112) and d A° varies from 2.77° to 3.31° (Figure-5). In silt sized fractions of primary phosphorites, the carbonate-fluorapatite is the most dominating phase as Indicated and supported by the above X-ra)r'diffractogram. The obtained values of lattice parameters, (hkl), cell dimensions (a and Co) d A, intensity, angles on chart in degrees, etc. supported the occurrences of 'cellophane•. The sharpness of the graph on the 99 o \ r- 0) u. (TJ c o 1 e J3 O l- •» o01 <". r~\ /o •o > o o • ! ON no xxo u V. 00 o en II •»> • o 3 « •\K0 2 Q- o U CO H|( «\ um. c N 1- if U 5 o Ou *-* U) o w 4-< x: 'C V— "5 0) §. c o > is x: CM Q) a. (M 3 o en M ^**\ o o X) c ro •H (J) T-H 'a (\1 • »» U) CD c • HH ^ o o • r^ ^« M E c o O < u -=« • fl3 i:; :t o o '^ u. o »- «J (0 ^ Q o >.? •£ > oj a oO ct: ^ -- CO A u a X cu ^ .•-• O) 4-> «N <0 — O < LL (!) I11JI/VA/WOV CO CD I I ' ' I I I I 100 x-ray cliffractograms are further supported the author's mega scopic, microscopic and scanning electron microscopic (SEM) studies on these phosphorites. Pew graphs in the figure indicated the presence of quartz as a major gangue mineral. The carbonate- fluorapatite phase further supports the occurrences of crypto- to microcrystalline, megacrystalline, amorphous, pelletal, cements, collophane, phosphatic.^ etc. and on the other hand, quartz supports the assemblages of chert, quartz-veins and/silica- veins and silica as cementing material in these phosphorites. X-ray study of the bulk samples of clay fractions (fine) of primary and secondary phosphorites were also carried out on the chart interval of 1° from 4° to 54° with the help of X-ray diffractometer. The carbonate-fluorapatites phase for a varies from 28.00° to 53.45° and for Co is 26.2° and cell dimensions varying in a^ from 9.310 to 9.359 (9.310, 9.317, 9.342, 9.318 and 9.359) and Co is 6.780; intensity of a^ varies from 8 to 100 o and for Co is 33 only. The lattice parameters (hkl) for a are o (210), (300), (310), (400) and (410) and for Co is (002) and d A° for BQ from 1.71 to 3.0537 and d A° for Co is 3.39 only (Figure-6) Among gangue minerals quartz varies on chart angles from 26•SO to 50.20 ; intensity from 14 to 100, the lattice parameter (hkl) is (112); and d A°, from 1.81 to 3.32. For goethlte chart angles vary from 18.00° 21,08°; intensity from 19 to 22; lattice parameters (hkl)(020) and (110) and d A° from 4.21 to 4.92 only. 101 The tnuscovite chart angle is 9,18°; intensity, 35; lattice parameters (hkl) (002) and d A° is 9,625 only (Figure-6). The clay fractions of both the types of phosphorites as shown in the above X-ray diffractograms indicated that carbonate - fluorapatite is the most dominating mineral phase in these phosphorites. Most of the graphs are shorter (except one) reveal cryptocrystalline and amorphous# types of cellophane and as a cementing material. The data obtained from the X-ray diffracto- grams is very close to the 'cellophane• more or less similar to silt sized fractions of cellophane. Quartz is the moat dominating phase among the gangue minerals of these phosphorites. The presence of quartz in the x-ray diffractograms supported the gangue mineral assemblages like quartz, chert, which constitute the cementing materials. The next gangue mineral is 'goethite' in the clay fractions of these phosphorites. The presence of goethite in the clay fractions supported the mineralogical assemblages which were identified during megascopic, microscopic and scanning electron microscope studies are hematite, magnetite, limonite, iron-oxide, and ferruginous content as cementing materials. The gangue mineral in clay fractions is muscovite mica represented by chlorite, sericite, decomposed feldspars, and finally clay minerals (kaolinite, illite, montmorillonite, etc.) which were already identified in megascopic and microscopic study. 102 tn c •rH *-> 1—eo oo ^ u • --> -< II 4- •H ^ 1 o 1-1 4-1 CI UN • »^ ^-^ ^-^ vO 00 n. 4-" »-^ Xr\ m Al JO CM \0 ro •H^O II 11 tl 4-1 l>. • • • « * x>i-o o o UA 0 ro M r^ o ro .. O N t-( CO c 1 m "^ « O-' -> >-i II '\J <-< :f o vO rM M^ »-^ '.M ® M rO r. ro O The XRD study of silt sized fractions of bulk samples of secondary phosphorite were also carried out separately with the help of X-ray Diffractometer on chart angle of 1 interval from 24° to 54°. The carbonate-fluorapatite phase of apatite is the most dominating. The lattice parameters (hkl) of carbonate- fluorapatite phase in a^ are (210), (300), (212), (400), (213) and (410) and for Co (hkl) is (004). The angles varies foT a^ from 25.95° to 52.40° and Co is 53.20°; intensity for a^ varies from 6.9 to 100 and Co is 10.5; and d A° for a^ from 1.74463 to 3.43011 and Co is 1.72028. The cell dimensions of carbonate- fluorapatite in secondary phosphorite in a varies from 9.329 to 9.399 (9.329, 9.399, 9.338; 9.3433, 9.336 and 9.335) and for Co, 6.881 (Figure-7). Besides, carbonate-fluorapatite phase in the secondary phosphorite samples, quartz is a major gangue mineral. This presence of quartz supported the occurrences of chert, chalcedony, and silica-veins and silica as a cementing material in nil the samples. The angles in which quartz falls is 32,20°; intensity 45; lattice parameter (hkl), (112) and d A° is 2.7775 (Figure-7). A comparison of data obtained from XRD analyses of silt- sized fractions of primary and secondary phosphorites indicates that there are much difference between the two in their lattice parameters, cell dimensions, intensity, d A°, chart angles, etc. The XRD data of carbonate-fluorapatite phases of primary 104 phosphorite samples are very close to those of 'Collophane' and in secondary phosphorite close to crandalllte (calclum- alumlnous-phosphate)(ASTM File No, 16-162). Thus, the XRD study of phosphorites now confirmed that silt and clay sized fractions of primary phosphorites contain •cellophanes• and in secondary phosphorite particularly, the silt sized (coarse grained) ones are made up of •crandalllte' as^a phosphatic mineral constituent. SUMMARY s The megascopic, microscopic, scanning and X-ray study of the phosphatic rocks of the Gangau Iron Formation' in the study area revealed that there are two distinct types of phosphorites viz., primary and secondary, Mlneralogically, the primary phosphorites being associated with shales, ironstones and quartz-breccia are mainly composed of collophane, a carbonate- fluorapatlte phase and in secondary phosphorite having the same rock associations are as crandalllte is the predominant phosphorus mineral usually occur as primary phosphorite as pelletal, oolitic, ovlulitic, granular, cryptocrystalline, micro to megacrystalline, disseminations, radiating, amorphous, recrystallised as thin veinlets, nodular shaped,etc. In m secondary phosphorites, th^ crnndnlTit*^ occur monUly nn Int.h shaped in the pores, d^vities, voids, fissure fillings, etc. It also occurs as pelletal, ovular/ irregular grain etc. Quartz is the most predominant mineral among the gangue constituents in both primary as well as secondary phosphorite. The other common gangue minerals are hematite, magnetite, limonite, goethite, muscovite, serlcite, chlorite, kaolinite, ilmenite, rutile, cherts, feldspars etc. cemented in a common groundraass of ferruginous and siliceous materials. 106 CHAPTER - V DISTRIBUTION OF MAJOR IONS & OHEIR CORRELATION V,l. GENERAL STATEMENT : The present study has indicated that within the inter preted and inferred- basinal conditions, the chemistry of basinal waters and subsequently post-depositional alterations played significant roles in producing different varieties of phosphorite in different proterozoic basins. The original composition of the sedimentational water was of prime importance. Conceding the facts that some of the trace elements and as well as that of the major mobile elements were either introduced into the apatitic mud or left the indurated apatite. The concentration or depletion of major and trace elements was dependent primarily on such factors like their mobility with respect to apatite associated assemblage of elonents, type and intensity of weathering and the effects of secondary processes. Various elements, both major and trace which combined to form phosphorite of a particular conpo- sitions changed their characters in course of geological history. In spite of such addition or substractions of the primary elements, they left some traces of their presence in the original sediments. These have been used for making significant interpretations about various palaeo-environmental condition (see Saigal and Banerjee, 1987) . 107 The inter-correlations of elements bring out three major associations such as - (1) apatitic-phosphorite, (2) ferruginous- clayey phosphorite^ and (3) weathered (leached) aluminous- phosphorite • Each element association reflects a grouping of elements - (a) structurally substituted in major mineral apatite, (b) adsorbed on to the mineral surface or (c) existing as discrete minerals derived from apatite by weathering* Host elements actuaLl exists in more *than one associatipn (see Banerjee, et al.* 1982). Some salient features of the phosphorites of interest are - 1* Association with carbonate minerals* 2. Presence of black shale, pyrtte and other features of reducing environment. 3. The role of organic and inorganic process in influencing I the concentration and precipitetion of phosphates. 4. Occurrence of sedimentary ^arlte involving extensive isomorphous substitutions of both cations and anions. 5. The vast areal extent of phosphorites considering the low phosphorus of the present and. past sea-water (see Wedepohl, 1970; Subramanian, 1930). The variations in major and trace elements abundance are indication of a change in environmental condition of deposition (see Mahadevan, 1985). The concentration and kind of element adsorbed or entering into the crystal stzracture depend on a number of factors, such as ^H, Eh, nature and structure of the adsorbant, availability and concentration of ions (see Krauslcopf, 1967), rate of nodule growth, nature and rate of sedimentation and various other parameters (see Cronan, 1969; Ghosh, 1975; Glasby, 1977 and Roy, 1981). Because such varied factors have complex interaction elements in nodules can occur in several chemical association as weekly adsorbed, strongly adsorbed or in the structure of carbonate or oxides of Mn and iron (see Ghosh, 1988). V.2. DISTRIBUTION OF MAJOR IONS : The chemical analysis of the phosphorus and their host rocks belonging to the Bijawar Group of Mardeora-Hirapur area/ districts Chhatarpur and Sagar (M.P.) were carried out at the N3RI , Hyderabad (A.P.) and the IRE Ltd. Chhatarpur, district Ganjam (Orissa). A total 63 rock samples from the above rock group were analysed for the qualitative and quantitative deter minations of their major and some trace elements and the data so obtained, presented in Tables-II, III, IV and V. Among the Bijawar rocks, the higher concentration of ^2^5 ^^® recorded from the samples of shales, ironstones and quartz-breccia. The phosphate content is very low in the basal rock units of the Bijawars. T^he concentration and dispersion pattern of thirteen major oxides of phosphorite collected from the Mardeora-Hirapur area are discussed in the foregoing pages. 109 V,2,l. Phosphorus Pent^oxide (P2Q5^- * Goldschmidt (1923) classified phosphorus as siderophile probably because of the presence of this element as schrciberisite ((Fe, Ni)3 P> iin iron meteorites. Dietz, et al. (1942) reported that the phosphorus which is probably present in sea waters at a few hundred metres depth, is essentially saturated with ^^2^^^A^2 According to them, if the ocean is saturated with tri-calcium phosphate, an amount of phosphorus equal to that carried annually to the seas by river must be precipitated because the phosphate saturation point depends on the ^H, changes in biological or phvsicochemical conditions which affect the concentration of phosphate ions.and consequently cause solution or precipitation of phosphate (Lerman and others, 1975 and Pettijohn, 1984), Ocean circulation gyres driven by the trade winds and westernly winds have strong divergent upwelling in the trade wind belt on the eastern sides of the oceans; these gyres have been suggested as the mechanism for marine phosphogenesis (Kazakov, 1937 and 1950; McKelvey and others, 1953; McKelvey, 1967). However, the most effective circulation systems in so far as phosphogenesis is concerned equatorial upwelling during episodes transitional from high level, warm oceans to low level, cold oceans. The effectiveness of the upwelling of either type depends on the interplay between deep-ocean richness of phosphorus 110 and the intensity of upwelling (Kazakov, 1937; Klemme, 1958? Kelvey, et al./ 1959; Strakhov, 1962; Smirnov, et al., 1962; Sheldon, 1964; Legeros, et al.# 1967; Saffir and Rubin^ 1970; Russel and Trueman, 1971 and Sheldon, 1980). It is known that fluorapatite is formed under strict 2 2 11 condition. In the system Ca - HPO^" - HCO3" - F " - HjO, only 2- 2- when the concentration HPO^ is higher than that of Ca or HCOo*** fluorapatite can be formed. In case of higher concentra- tion oH COj/ tho inciin phonphnto minorol lormod Ij; nroncolito, but the sodimenhary phosphorite on the Yangtze landmass IS composed mainly of carbo-fluorapatite. From the section of the phosphorite bearing sequence,it is clear that phosphate minerals were deposited prior to carbonate minerals which reflect sedimen tary sequence francolite and calcite. Generally, francolite is completely precipitated only when pH is from 6.5 to 7.5 (Simpson, 1966; Gowda and Rajulu, 1980; Liang and Chang, 1984). Pertinent synthesis are rare most apatite synthesis have been done at elevated temperatures (Jaffe, 1951 and Deer, et al., 1962) and most attention has been given to hydroxy-apatite owing to its physiological importance. It is inferred that during the early Proterozoic, the stable platform (Protoplatform); had been formed. The Jiangsu- Anshui-Hubel phosphorite belt was once located on a continental shelf within the trade wind zone. A stable, tectonic setting, a lit warm and dry palaeoclimate and the uprise of cold P-rlch ocean currents resulted in the concentration of phosphate is that belt, forming the series of phosphorite deposits (Long Kang and Zhendong, 1988)• The diagenetic mobilization of phosphorus and the formation of apatite concentrations from interstltal waters in the model proposed by Bushinskii (1966) and favoured by Kolodny (1978) in a recent view of the genesis, phosphorites. This is also the opinion of the Price and Calvert (1978) based on a geochemical study of phosphorites from the Namibian shelf. They conclude *the origin of the phosphorites is believed to be the result of the diagenobic precipitation of phosphorus within sediments'. Finally,the fact that no clear correlation could be found in phosphorites between petrographic types and chemical composition" (Gulbrandsen, 1966; Nathan, et al./ 1979) also points to an early diagenetic environment for the genesis of phosphorites, Ouir interpretation that the Central California margin phosphorite are the result of direct interstitial precipitation is supported by recent experimental data vfhich have demonstrated for the first time, that carbonate-fluorapatite can given sufficient time, precipitate from marine waters simply by increasing the phosphorus and fluoride content via degradation of organic material (Gulbrand- sen, 1966; Cristopher and others, 1970 and Gulbrandesen, et al., 1984)• m Al-Bassam, et al• (1983) reported that most of the phosphate in the Campanion-Maastrlchtian depositional basin in the part of Iraq was syngenetically precipitated as phosphate mud at the sediment-water interface, mixed with fine quartz, clay minerals and carbonaceous matter. Further, they added that the intensity of phosphate precipitation was greatly increased in certain periods only, giving rise to the phosphate bearing horizon, when physico-chemical condition favourably for apatite precipitation and preservation occurred (Al-Bassam, et al.* 1983)# Properonts of direct precipitation of phosphorite on continental shelf areas as a result of rise in ^H and tempera- tur«rt (Yoni^fl*»f, l*)5fl, 1965r Krnuskopf, 1967 «iv1 Putw^rdhnn r\n<\ Ahluwalia, 1973). In Florida* the environments which have the maximum (l(5volopincint t)!' Ulio f>h')ni>nori»,« onillinfMil.n nr« tha shallow water coastal and nearshore shelf platforms associated with the structural highs (Riggs, 1979). Bushlnki (19 64) and Gulbrandsen (1969) also find that most of the major marine phosphorite deposits of the world were of a shallow water origin (Cgrrozzi, i960; Berg, 1972; Birch, 1977 and Howard and Hough> 1979). It is felt by more and more people that some kind of a trapping mechanism for the accumulation of the phosphorus carried up continental margin by the upwelling currents of the 113 oceanic waters is necessary for the formation of phosphorite deposits. This mechanism should obviously be related to the regional basin topography and palaeogeographic and palaeotectonic conditions (Patwardhan and Panchal, 1984). It has also been assumed that the phosphatizing medium was sea-water or sediment pore-water acting during very early diagenesis when diffusional and convective contact with sea-water maintained the oxygen isotopic composition at sea-water values (Benmore, et al^^ 1984)« Gulbrendsen (1969) proposed few mechanisms for the formation of apatite in the marine environments, direct precipi tation and replacement of CaCO^- Parker (1975) on analyzing 53 samples of typical marine phosphorites found that there is little variation in the average Po^c content between sample localities (23,9 - 25,9H)# although absolute values ranges from a minimum of 11.5% P2O5 to a maximum of 31.0% ^n^S' ^^^^ ^^ average of 24.4% P2O5 for.all the 53 samples analysed. Mullin and Rasch (1985); Lucas and Prevot (1975) noted that a reducing environment was useful for mobilization of phosphorus but a more oxidizing one is necessary for phosphate genesis. According to Krauskopf (1967), the precipitation of apatite requires the concentration of PO^ ion to be increased to the point that solubility product (S.P,) of the following simplified reaction is exceeded s- 114 Cag ^PO^)^ F > 5Ca^+ 3P0^~ + F SP - [ Ca^^f [PO;M' [ F- ] The POf" concentration is affected by its reactions with H**" according to the following reaction j- H3PO4 > "2^°4 "*• "^ H2P0;j • • "PO4 + J^t HPO^"" > Po|" + H"^. Thus, the PO4 concentration is dependent on the pH of the system and higher the pH the greater the percentage of PO^" ion to the total dissolved phosphate. The pH of the ocean water is controlled primarily by the reactions of CO2 and water to give Carbonic acid, so that the more dissolved CO^ the lower the pH at any give alkalinity. PO^" forms a number of complex ions, of which perhaps the most important to sea water, phosphorus reaction is the MgPO^ ion (Goldberg and Parker, I960; Kramer, 1964; Roberson, 1966; Krauskopf, 1967; Gulbrandsen, 1969; Atlas, 1975). Any such complex ion formation reduces the concentrations of PO^" ion. The solubility product of the reactions forming apatite is affected by temperature and pressure. Both the decrease of temperature and an increase of pressure increase the solubility product or make apatite more soluble. In addition lower tempera ture and higher pressures allow increased partial pressure of 115 dissolved COj* which decreases pH in the ocean water. Thus for several reasons decreases of temperature and increase of pressure tend to change the sea water chemistry toward undersaturation with respect to apatite. Sheldon (1980) discussed that on the contrary increase of temperature and decreases of pressure tend to change it towards saturation. With progressive leaching/weathering of the carbonate fraction, the grade of ore in terms of Po^c also increases (Choudhuri, et al., 1980; Sant and Sharma, 1984). The environment of the phosphorus may be related with the velocity of sedimenta tion. In general, rapid sedimentation is unfavourable for the enrichment of phosphorus. It is obvious from the rock assemblages that slow sedimentation is very important factor for the environ ment (Liang and Chang, 1984) . In several regions of the world, marine sediments are reported to contain more than lOOOppm phosphorus (Subramanian, 1984). Riggs (1980) reports that sediments off S.E. Coast of U.S.A. contain as high as 40% P-O^ (about 17,000 ppm P) but these are as stated by him, likely to be detrital continental apatitic grains derived from earlier phosphate deposits (Hashmi, et al., 1978 and Subramanian, 1984). Jitts (1959), it is quite likely that major portion of the phosphate associated with the acid soluble fractions is tied up with the sedimentation in the adsorbed state. The fact that - 116 (i) the waters are characterised by high concentration of phosphate, (ii) large quantities of finer minerals are kept in suspension as evidenced by the turbidity of the waters and (iii) silts are capable of adsorbing larger quantities of phosphate and that in the natural state they seldom approach saturation with phosphate. Phosphate associated with the acid soluble fraction of the sediments i.e., in association with tho carbonate phase and/in adsorbed state can occur in at least two kinds of associations - (i) in areas of high organic productivity associated with reducing conditions during their formations and (ii) in areas which do not have a high organic productivity and associated with oxidizing conditions in the environment (Parop- kari, et al-, 1991). McArthur (1978,b) and Reedman (1984), the phosphate content varies considerable with particle size and there is a gradual increase in phosphate grade with depth. This is partly due to lateritization processes near the surface which have increased the iron content at the expense of the phosphate content, but it is mainly due to partial solution of apatite in the shallower zone and reprecipitation as, secondary apatite (Staffelite),at deeper levels. Phosphorite precipitation has been attributed to purely chemical factors such as loss of carbon-dioxide and increase in pH resulting from warming of phosphate rich waters by Kazakov (1937), McKelvey, et al. (1953). Although, it has been 117 suggested by Sheldon (1981) that this mechanism is nonfunctional to form phosphorite in the present sea» It is considered to be the most powerful mechanism involved in the formation of the ancient phosphorites (Kazal(pv, 1937; McKelvey, et al., 1973; Sheldon, 1964, 1980; Frees and Riggs, 1965; Riggs, 1979). Phosphates of divalent metals with additional anions (OH, F, 0, sometimes Co or in the form of acid phosphates are most stable, also when the compounds contain relatively large cations (Ca, sr and sometimes Pb) (Betekhtin, 1959). Bremner (1975) concludes that precipitation occurred in shallow, warm lagoons which were periodically disturbed by storm- generated waves and pellets resulted from the disruption of semi- lithified cellophane muds. He further believed that the warm waters, high phosphate content of upwelled water circulating into the lagoons, high pH from decomposing organic matter and high CaO/MgO ratio would favour direct inorganic precipitation of phosphate. Sholkovitz (1973), suggested that the interstitial water composition (SO^", alkalinity, sulfide, Ca"*" , Mg"^ , K"*" , Si"*' , OH4, phosphate, NO2, NO3, NH^ and Cl"%) of both the basin sediments in the centre of the Santa Barbara basin and the •slope* sediment shallower than the basin silt is compared. The basin sediment is deposited in sea water which is almost anoxic (0.05-0.1 ml/1 of O2) whereas the 'slope" sediment is overlain which is more oxygenated sea water (0.3 - 0,4 ml/1 of 0^) 118 Martin and Harris (1970) found that the rate of addition of phosphate to sea water and the corresponding rate of crystalli zation had no effect on the nature of precipitate formed. The pH remained between 7.5 and 8,0 (Degens, 1972), The P^Oe content of Maton phosphorite deposits district Udaipur (Rajasthan) is as high as 36% (Banerjee, 1982). In the Jaiselmer phosphorite deposits of the Mesozoic age (Viquar, 1981) the P^Oc content varies from 5 to 15%. The ^2*^5 content of Mussoorie phosphorites varies from 15 to 35% (Gokhale and Rao, 1950). Rock from the weathered zone (also termed as Al-phosphate zone or the •Leached Zone') characteristically contains 8% to 12% P2^5 ^"^ about 0.012% uranium in contrast to the unaltered phosphorite which commonly has 10-15% P2*^5 ^"^ about 0,008% uranium (Altschuler, et al., 1956). Along the continental margins phosphorites contains P2'^5' several to 33%; CaO, 7-52%; AI2O3* traces - 7%; ^e^O^, 0.1 - 50%; Si02, 0,1-48%; QO^* 3 to 29%; F 4 1^3; organic matter from 0.1 to 3.4%. The phosphatic matter of sea-floor-phosphorites consists of fluor-carbonate apatite. According to chemical analysis it contain, 30-32% P2<^5'' 46-48% CaO%; 0.5 1.9% MgO; 0.1-0.5% K2O; 1.4-2.3% Na20; 3,8-4,3% CO2; 1.3-1,7% SO3 and 2,8-4.1% F. (Baturin. 1975 and Bliskovsky, et al», 1975). P^Oc in the primary phosphatic rocks (shale, ironstone and quartz-breccia) of the study area varies from 14.79 to 25.05% 25.99 to 29.70% and 15.32 to 2 8,30% and the concentration Of P2^5 in the secondary phosphates ranges from n^ CM ro CM CO CM Cv» O + o C^ A UJ I— GO o CL LU tn UJ in \— (/) < CO (/) Q 00 • • -r- liJ a: O in li- c4 "T" -I r iO -r to ^r^ s o ^ ro 120 32.10 to 42.83% (Figure-8 and Tables-II and IIIA). The occurrence of 'phosphate* in these rocks supported the following aspects of genesis j- (1) The occurrences of 'Collophane' and phosphatic cements in primary phosphorites and crandallite in secondary phosphorite samples supported the higher content of phosphate. (2) The very high content of phosphate in secondary phosphorite samples indicated the weathering and/leaching of primary phospho rite ores and refilled the phosphate in the cavity/voids/vein- fillings. The higher content of phosphate also due to removal of 'gangue* minerals from the primary rocks by groundwater action and auistotia ooo l®v*9l ahangos fsnd du« to notion offl«f» wAvew , tides and low currents. (3) The absence of organic content in these phosphorites indicated the direct and inorganic precipitation of primary phosphorites and diagenetically by secondary phosphorite. The Eh and pH of the Bijawar basin may be around 0.00 to 0.20 and 5.8 to 7.5. (4) The removal of the carbonate by phosphate may be within the basinal waters before the final precipitation of these phos phorites. But there is no replacement of CaCO-a by PO. as post- depositional in this area. (5) The crypto microcrystalline cellophane in primary phos phorites indicated the moderate to very shallower and marine 121 conditions of the basin at the time of formation of these rocks. (6) The association of phosphate among three different rock types is indicated the wide variations of physical-chemical condition of the basinal-sea waters and they may be contemporary formations particularly primary phosphorites. The primary phos phorites may also started leaching/weathering Just after the formations or the weathering started after a long time by^ground water action and/sea waves* tides and currents. (7) The upwelling currents from deeper to shallower waters also played an important role for the transportation of soluble phosphate contents towards the continental margin in the shallower part of the basin and finally formation of marine phosphorites. (8) The humid to arid climatic conditions also favoured the genesis of the^e phosphorites. The presence of carbonate-fluor- apatite phase in all four types of phosphorites indicated the prior formation of calcite in the limestones and later formations of cellophane and crandallite in the phosphorites around pH 6.5 to 7.5. (9) The occurrences of phosphorites in the^Gangau Iron Formations in the Bijawar basin indicated the highly oxidizing conditions of the basin. (10) The inixinq o( prinintyfluthoyoiilc nw\ difigtnir^li c oecondnry phosphorites may be occurred due to transgressive/regressive cycles of basinal-sea due to super imposition of environmental regimes. 122 (11) The phosphorites are epigenetic and precipitated as phosphate muds at the sediment water-interface and mixed with fine quartz, iron and clay bearing minerals in the study area. The intensity of phosphate precipitation was greatly increased in certain periods only, giving rise to the phosphate bearing horizon, when physico-chemical conditions favourably for apatite precipitation and preservation occurred. (12) The 'trapping• mechanism of phosphorites genesis may be possible on the regional scale in the Bijawar basin from deeper to shallower continental margin by upwelling currents due to temperature and pressure variations and action of winds and sea- gyres. This mechanism may be related to palaeotopography, palaeo- geography and palaeotectonic conditions in the marine waters. (13) The higher concentration of phosphate in these phosphorites further supported the slow sedimentation of phosphorus from the source rocks. The brecciations, vcJids, cavities, vein-fillings are the suitable features for the accumulation and preservation of phosphate content. The higher phosphorus content may be due to above features particularly in the samples of quartz-breccia and secondary phosphorites. (14) The hiqher concentrations O^ phosphate may be rjue to adsorption by ferruginous colloidsJ and gols an (15) The genesis of secondary phosphorites may be due to lateritisation of primary phosphorites by chemical leaching and/ weathering processes in the area- (16) The formation and presence of crandallite from collophane (apatite) in the secondary phosphorite samples clearly indicated the product of 'leached zone*. V.2.2> Lime (CaO) : Calcium falls in the lithophile group in terrestrial rocks (Goldschmidt, 1923). According to Montgomery (1979) calcium is precipitated as calcium-carbonate either by a purely inorganic process or by the action of various organisms. High calcium concentration in the phosphatic rocks has been reported at Sechura in Peru (55%) and Birmania phosphorite deposits, district Jaiselmer (Rajasthan) (Viqar, 1981). Phosphates of divalent metals with additional anions (OH, F, 0, sometimes Cb) or in the form of acid phosphates are most stable, also when the compounds contain relatively large cations (Ca, Sr and sometimes Pb) (Batekhtin, 1959). Calcium is the only one of the common metals in geologic environments that forms such structures, calcium phosphate in its many varieties is by far the most abundant inorganic compounds of phosphorus. The inorganic geochemistry of phosphorus is largely a study of c4 124 C4 roj o + 0 00 u a: A o CL UJ en t: o vO cr a: X UJ o o a. Q- Lin ti t/) in (T o X a CJ O O X Q_ CL O if) a. UJ O > s X UJ m L^ < a. Q NI u o en CE: o u o < < tu 3 eXn ui cr C5 to — rNi ro ^ DC LU CQ CD 00 I LU CO _l O. Q tn < cr- CO LJ cr en z> CD -T T" —r- O o ^ in 4 o (5 125 calclum-phosphate, just as inorganic geochemistry of carbon is largely study of calcium-carbonate (Krauskopf, 1967), The solubility of Ca-phosphate is highly dependent on pH, the mineral and dissolved chemical species involved and surface effects. Chemical analysis of phosphorite shows the material to be mainly hydrous tricalcium-phosphate with varying amounts of calcium- carbonates and fluorides. Because of admixture of non-phosphatic materials, such as calcite, dolomite and chalcedony as cement and also detrital contaminates such as quartz and clay* analysis are highly variable (Pettijohn, 1984). The calcium is the well known and most significant element in the chemical formula and crystal lattices of apatite which has been reported from almost all the phosphorite deposits of the world. In the study area, (1) The CaO in per cent weight varies from 22.27 - 35.0^ \u ohole phoaphoritea; 40.42 - 49.'ll in secondary phosphorites; 32.19 - 37.59 in ironstone-phosphorites and 17.95 - 40.98 in quartz-brecciated phosphorites, (2) The concentration range of CaO is very high in secondary phosphorites, (3) Generally/ the higher the P2*^5 content the higher is the lime content in the phosphorites, (4) It is precipitated by the inorganic sedimentary process due to absence of organism in the marine, shallower conditions, (5) The formation of calcium- phosphate is also rlopendent on the variation of pH of baslnal waters and addition of non-phosphatic materials like quartz, ferruginous and clayey minerals and some extent cementing materials (Fig.-9 and Tables-II & III A). 126 V>2«3. Carbondioxlde (COo) « Moist climate is especially prolific in the generation of CO2 making the solution of the lime carbonate rapid, thus developing residual phosphate deposits (Hummel, 1911). The chemistry shows that these carbonate-fluorapatites are poor in CX)2 content. In more weathered phosphorites, mineral phases of crandallite are more prominent, inspite of the presence of a dominant apatite phase. In carbonate-fluorapatites, 4% CO2 is considered to be the normal concentration, consequently the low CO2 values of the Hirapur-Bassia apatites is due to the processes of decarbonation, caused by the dissolution and re- precipitation. There is a general tendency for the depletion of CO2 in these apatites leaching to formation of fluorapatite. This CO2 is an indicator of hidden-weathering in the rocks (Banerjee, et al./ 1982). The average 'apatite' CO2 content of phosphatised lime stone was 5.7% which is high relative to the * apatite' CO^ content (1.8%) determined for the Phosphoria Formation of the western United States (Gulbrandsen, 1970). The influence of CO2 is so often mentioned in the leaching of limestone and phosphate rock. The CO2 has very littlo csfffsct on Uho amount of phoophorua tnk«n into solution, whether from lean phosphatic limestones or from 127 apatite. On the other hand as is well known the amount of lime leached is greatly increased by the passage of CX)2 through liquid. This means that the concentration of phosphate is more likely to be in the residual surface bed in case CO^ is abundant than in case it is sparingly present (Graham, 1926). Kramer (1964), calculated the solubility products of carbonate-fluorapatite of log K = -103 at 5*^0 and log K = 105 at 25°G, which showed a small decrease in solubility with increase in temperature over a range representative of natural conditions. The other temperature effect is indirect and is due to the inverse relationship of temperature and CO2 solubility; and because CO2 solubility is inversely related to pressure, tempera ture and pH are directly related. An increase in temperature of sea water therefore is likely to results in an increase of pH and a decrease in the solubility of apatite. Temperature increases then act to decrease the solubility of apatite (Cameron, and Hurst, 1904; Pevear, 1966 and Banerjee, 1978). According to Rubey (1951) the effect of pressure on the equilibrium focuses mainly on the equilibrium of CO^ gas (atmosphere) and CO2 aqueous (sea water) and consists chiefly of two aspects. One is the consideration of the atmospheric content of COj throughout geologic time. Any appreciable change from the present would significantly affect the apatite sea water equilibrium but possible changes are at5^present only 12S speculative and the weight of most evidence favours no or little change at least since the Cambrian times. The other is a pheno menon that may occur in the deep portions of the ocean where pressure is high. The 'normal' carbonate-fluorapatite has about A% CO2 in the lattice and a F/P20^ ratio of about 0.12 (Nathan, et al.# 1979), whereas the apatite in these nodules has less than 1% CO2 and a ^/"^n^S ^^^^^ ^^ about 0.10. The only possible way of achieving such a decarbonation by a sedimentary process (low temperature) is by dissolution and reprecipitation, since a relatively high amount of energy is needed to expel CO^ from the apatite lattice. It can also be seen that the de-carbonation is accompanied by the partial loss of fluorine (Mathews and Nathan, 1977). Authigenically derived phosphatic rock from Saldana Bay and the S.African shelf contain an average of 2.6% and 1.8% CO2 respectively. These values are markedly different from the CO2 content of the apatite phase in phosphorite rocks of the replacement type which has been determined by both Parker (1971) and Birch (19 75) to be 5.5% (range 4.8 - 6.1%). It would appear from these figures that the highest CO2 values are associated with phosphorites formed by replacement of calcareous sediments, whereas low COj volues ore related to authigenic varieties which originated in carbonate-poor sediments of Agulhas bank of S.Africa and west coast of S. Africa. 129 The CO2 content of concretionary phosphorites from S.W. Africa encompass a wide range of values, i.e. 1.17% (Baturin, 1969) and 3.6% (Bremner, 1978) to 6.3% Baturin (1969), whereas the values of Miocene pelletal material vary between 2.6% for Saldana Bay (Birch., 1975) and 5.5% for S.W. Africa (Rogers, 1977). Thus phosphorite materials formed in similar environments and of the same age have a widely varying CO^ content. Leaching during weathering has been shown (McArthur, 1978f several authors (McArthur, 1980; Lucas, et al., 1980) to post- depositional submarine or terrestrial weathering. CO2 is an essential component of the mineral substances of phosphorite, teeth, bones, etc. The principle of inorganic chemistry seems to be in edge to account for phosphorite (McConnell, 1965). Further upwelling causesctls^integrated the precipitating cellophane and transportation towards the coast and attrition of th^ produced grains. During and nftor the upwelling period part of the COj originally produced by the decay of the organisms escapes out of the water (El-Taroblli, 1969; and Stumm, 1972). In the Hirapur area, the significant CO2 content and effects of secondary weathering processes in these rocks suggest that mineralogically these phosphorites are nearer to the basic composition of fluorapatite. The transforma tion of original carbonate-fluorapatite mud to flour and then finally to crandaLlite (first in the weathering series crandallite- millisite) is therefore a secondary feature (Banerjee, et al.* 1962), The association of CO2 like CaO is also very important and signifcant for the synthesis of apatite in the sedimentary environment. In the study area, the CO2 content varies from 0.89 to 2.85% in shale-phosphorites; 0.79 to 1.81% in secondary phosphorites; 0.95 to 2.03% in ironstones phosphorites and traces to 2.01 in quartz-brecciated phosphorite samples. The CO2 content c4 131 + O o /^ o CO CM o O QL o i/i O u. o LU in Q: < LiJ X z to if\ CQ o ^ fs» f*> ^ D Z) Z m I a: UJ I— _J (/) CL Q < LT) CO UJ a: ID CD J" c4 I— —r- —r- —r- —T" —r- —I- —r- o oo CO CSJ O IN CO o en o4 o oCM < o 132 has higher concentration in primary than in the secondary phosphorites• Low concentration of co^ particularly in the ' secondary phosphorites may be due to lateritisation and loss of CO2 (Figure-l.q and Tables-II, III ^) ^ (1) In the itudy area, the low content of CO^ indicates the hidden weathering and the presence of crandallite parti cularly in secondary phosphorite further supported the weathering processes. The lower concentration of CO, in these phosphorites also indicated that phosphatic sediments were not the product of replacement of limestones etc. The upwelling currents are also responsible to bring the CO2 from the deeper parts of the basin along with P2^5' With the rise of temperature accompanied by decrease of pressure, some CO2 rT\ay be released from the basinal sea water. This mechanism favours the inorganic, direct precipitation in the shallower, marine conditions of the Bijawar basin* (2) The lower concentration of QQ^ in the phosphorites also supports the idea of epigenetic and authigenic origin and Proterozoic age of these sediments because ancient phosphorites are mostly characterised by low content of CO^. (3) The extensive silicification evidents the widespread occurrences of carbonate-fluorapatl.te (cellophane and crandallite) by diagenetic meanse are responsible for low CO2 content. (4) The presence of minor content of CO2 along with apatite crystals, quartz, iron and clay bearing minerals in these phosphorites indicated the 'mild' \yeathering. 133 (5) The presence of low content of CO2 m the apatite phase, protected the crystal lattices by ground water action during weathering/leaching of the rocks. The transformation of original carbonate-fluorapatite mud to flour and finall crandallite in secondary phosphorites is, therefore, a secondary feature. The low contents of CO2 besides leaching may be due to low grade metamorphism in the ancient phosphorites of Bijawar basin. V^2^4. Hydrogen Peroxide (Water) (H^O"*") s Veeh, et al./ (1973) suggested that contemporary phos- phatization occurs in bands Just above and below the oxygen minimum zone. In the study area, the H-O content varies from 0.002 to 0,81% in shale-phosphorites; traces to 3.01% in secondary phosphorites; traces to 0.13% in ironstone phosphorites and traces to 0.40% in quartz-brecciated phosphorites respectively. The association of very minor amount of water indicated the unstable conditions of the presence of hydroxyl-carbonate- fluorapatite phase of the apatite in these phosphate rocks. The low content of H20'^ particularly in the primary phosphorite sarrples indicated contemporary phosphatization of the Bijawar sediments during warm and arid climatic conditions. The higher concentrations of H2O in the secondary phosphorite samples + o • a: o Q- u o I— — X on a: OL UJ o OL k— o in to (X o X o a. Q_ Q: CM o a: z a. < ui o o < u s < o X UJ U) if) I—I c3 — fNj m m a: C/) UJ cr 2 S ^ II and III A). V>2,5^ Alumina (AI2O3) s The deposition of aluminium in the hydrolysates is almost quantitative i.e. the quantity of aluminium liberated from the Al-bearing minerals during weathering in quantitatively trans ferred into hydrolysates and only very little is found in precipitates as carbonates, oxidates and evaporates. Sea-water carbonate rocks constitutes only 2.5% of AI2O3 (Green, 1959; Birch/ 1980). Aluminium generally occurs as suspensates as well as sediments in nature. It mostly occurs in low temperature to humid areas and behaves as a clastophilic element in the sediments (Mason, 1966 and Birch, 1980). Mason (3-958) on the other hand opined that the accumulation of the products of chemical break down of aluminosilicates gives rise to a mud consisting essentially of the clay minerals, that are rich in alumina and also potassium by absorption. According to Palnier (1922); Lucas, et al. (1980) and Banerjee, et al. (1982), the apatites like those of Hirapur-Bassia area, district Sagar (M.P.) with low CO2 contents could be safely interpreted to have evolved through the processes of weathering. With 136 prolonged period of weathering, when carbonate was a]most completely leached out, other associated minerals were attracted with released additional cations like Al and Fe. In the argilla ceous host rocks, these released cations combined with available phosphates and formed crandallite, while in the alumina poor detrital rocks, fluorapatite remained the dominant phase and developed magnetite-goethite coatings. The abundance of clay-size material in the non-pelletal phosphorites, particularly the cellophane mudstones, results in a higher AI2O3 content and a much steeper regression line (Cook, 1972), High values of AI2O3 (average 7.67%) in Banded Garnet Amphibolite rock is possibly indicative of appreciable clay/ pellitic component in the rock (Bandyopadhyay and Roy, 1987). Silicon, aluminium and iron, on the other hand are generally soon redeposited as insoluble compounds; new minerals are formed from then at an early stages of weathering (Mason, 1966). Alumina concentration is highest in pelletal phosphorite (6.50%) of Cumbum phosphorites, Type-I phosphorite (6.26%) of Hirapur and phoscrete of Jhabua (4.26%). Petrographic studies reveal that pelletal phosphorite of Cumbum and Hirapur, both contain very high quantities of clay and other micaceous minerals (Saigal and Banerjee, 1987). The elements, Al-K-Ti-2r consistently group as clays and that with leaching of these phosphorites, Ba, Th, Ce, Ni and Sr 137 substitutes for elements in the clay structure or are adsorbed on to clay surfaces (McConnell, 1950 and Howard and Hough, 1979). It has already been stated that weathering played a major role in the formation of the phosphorite. The results obtained indicated that during weathering there is an overall/ though somewhat irregular, increase in most major elements located outside the apatite lattice (SiO^, ^203* ^®2°3' ^2^ ^^'' ^"*^' "2^^^^°^^' 1972; McConnell, 1973 and Literature cite<|>) • Major elements analysis indicates that the Central California continental margin phosphorites are grossly similar to the average phosphorite (Kolodny, 1981). Samples collected offshore from Pescadero have the highest percentages of P2^5 and CaO and the lowest values for Si02 and AI2O3- These results support our mineralogical and petfographic data which suggest that the Pescadero phosphorites are the purest of all Central California margin samples; this may be the result of concentra tions via reworking. The relatively high Si02 and AI2O3 values for point Sur and Twin Knoll phosphorite suggests that they havQ been more diluted by detrital quarts and alumino-silicates as well as skeletal opal (Mullins and Rasch, 1985). According to Banerjee, et al. (1982) that during the last phases of evolution of Bijawar rocks, land conditions prevailed with local fluvial influences and groundwater circulation through the exposed rock masses. The ferruginous 138 crust, so common in such environment were formed locally but the sandstone-shales developed more extensive ferruginous coating which also filled the intergranular spaces. This phase is associated with recrystallised alumino-calcic phosphatic cement which occur as vugs and/cavity fillings within the alumino- phosphate rich phosphorites. The irregular distribution of crandallite is also due to differential weathering of shaly apatitic phosphorites. The carbonate-fluorapetlte ^ crandallite (Ca) transformation in these phosphorites appear to be in their early stages, compared to phosphorites of the Sonrai area of the western Bijawar basin, where minerals of more advanced weathering stages > millisite > wavellite are also recorded. It is possible that the paragenetic aoquoncG woul^i hnvr^ boon tho onmn na Ihoao iOt^ntirjnd in i\)tj Sonrai area, west Senegal, parts of Florida, Rumjungle area in Australia and parts of U.S.S.R. provide the Hirapur-Bassia basin was not protected from the onslaught of weathering for a consi derable time after they were lithified and uplifted (Banerjee, et al., 1982). (1) In the study area, the occurrence of alumina particularly in the samples of secondary phosphorites are very important and genetically most significant due to presence of calcic-aluminium phosphate that is crandallite. The alumina content varies from 5.00 to 10,01% in shale phosphorites; 1.54 to 6.83% in secondary en 139 + 0 ok 5 /N ill y~ cr o o c4 CL llj UJ <^ H- O cr a: X 00 u o o CL Q- tl ian. (X en o o o o X X o CM Q. a. Q. o LT) u O tr X >• UJ en a. cr z in 1 < o LL Q fc— N u Z (/) a: o _i o z 4" < u o < — CO X u cc Q; 21 (/) in \—9 t^ *•" UJ O CD — — fN CO .c4 2 *- ::J _, - ^ ii^ "^ z ? O 1 cr UJ •- O* _. ^ Q- Q 4- ^^^ •~T— —T" —,— —I— J CO -:r phosphorites; 0,98 to 3.16% in ironstone phosphorites and 1.23 to 6.97% in quartz-brecciated phosphorites. (2) The higher concentration of alumina in the primary shale- phesphoritesmay be due to association of detrital grains and clayey minerals because most of the argillaceous rocks are having higher content of Al202* (3) In the ironstone phosphorite samples alumina is low and this may be due to lesser quantity of clay minerals and very high associations of ferruginous minerals (hematite, magnetite, goethite, limonite and ferric-oxides as cements) in the ore. (4) The presence of AljO^ in the phosphatic rocks indicates the humid to low temperate climntic conditions in tho study nren at the time of precipitation and phosphatization of these sediments. (5) The chemical break down of the alumino-silicates gave rise to mud-phosphorites by extensive leaching/weathering of the ores in which to some extent the other associated minerals (gangue) also attacked and released cations like Al and Fe. These released cations combined with phosphates replacing Ca in the apatite crystal lattices and finally formed crandallites in the secondary phssphorite ore. (6) On the other hand the poor alumina detrital rocks, carbonate-fluorapatite remained the dominant phase and developed magnetite-goethite-hematite coatings in primary phosphorite ores (Figure-12 and Tables-II & III A). 141 V.2,6, Ferric Ofltlde t Iron-oxides, including hematite (Fe^O^) are generally the products of near surface oxidizing environments (Eh, 0.0 to 1,10 and pH, 4 to 9). When humid conditions prevail in the weathering environment, the oxides of iron once formed, are stable and highly insoluble, A slight increase in either Eh/pH from the locus. Eh = 0.0, pH = 6, will shift the system into the field of stability for Fe20^. In addition, the Fe^O^ stability field may be shifted by increased concentrations of Fe '*" (Hubber and Garrels, 1953; James, 1954; Johnson and Swett, 1974). Krynine's (1949, 1950) hypothesis concerning the origin of red sediments related their development to predomi nantly topica-1-humid and warm. Savannah climate. According to Banerjee, et al. (1982) that the primary association of iron with phosphate is not established with certainty. The ferruginous content of the rocks, which gives them their colouring, is probably due to the oxidation of iron content of the detritus mainly at the time of transportation and sedimentation, but the fine grained hematite-rich pockets may be chemogenic in origin. Among all the Proterozoic deposits of India, Bljawar and Cumbum phosphorites contain highest contents of FejO-. Jhabua, Matoon, Jhamarkotra and Pithoragarh phosphorites uz contain comparatively low percentages of FCo^S* Although phosphorites of Bijawar and Cuddapah are markedly ferruginous, the primary association of iron with phosphorites could not be established with certainty. No iron-phosphate mineral has been Observed in these rocks. The absence of iron-phosphate minerals in similar situations have been explained as due to the promi nence of humic accumulations in the soils of highly humid regions and to the reducing effects of organic acids in waters draining these and also to the relatively higher solubility of the ferrous phosphate compounds that would tend to form (Altschuler, 1973). It is also speculated that being unstable, most of the iron and aluminium-phosphate undergo progressive alteration with continental weathering, Hirapur phosphorites contain very high amount of iron (Saigal and Banerjee, 1987). With prolonged period of weathering, when carbonate was almost completely leached out, other associated minerals were attacked which released additional cations like Al and Fe, in the argi llaceous host rocks, these released cations combined with available phosphates and formed crandallite, while in the alumina-poor detrital rocks, fluorapatites remained the dominant phase and developed magnetite-goethite cotaings. That iron was not readily available at the time of early phosphate sedimentation/ is evident from the fact that no iron-phosphate has formed in the sequence. However, in the 143 void-filling type remobilized and recrystallized phosphorites^ it seems that somfe of these voids and fissures were occupied by ferruginous laminations which have been systematically leached and isovolumetrically replaced by crystalline apatite grains, growing from the margins towards the centre of the void spaces. Such features suggest that small quantity of iron was possibly introduced into the system subsequent to primary phosphate sedimentation, possibly at late diagenetic stages on the sediment water-interface and was subsequently leached out during early stages of weathering. Widespread ferruginous coatings of all the rocks in the area is due to regional ferruginization process, which seems to have accompanied the regional silicification as the last stages of the geological activity in the region. It is also possible that some of the iron was introduced in the sediments through epigenetic processes (Banerjee, et al•# 1982). The basinal irpn-formations suggest that the environment of phosphorite and ironstone deposition have many factors in common. Each displays two contrasting facies - a cratonic or platform facies. (nodular phosphorite with glauconite and the oolitic ironstone facies) and a geosynclinal or basinal facies (the bedded phosphates and the bedded or nonlitlc ironstones). The basinal facies seems to require a somewhat anaerobic milieu, are with a slightly lower than normal pH and are in which clastic sedimentation is exceedingly slow or inhibited. The platform 144 facies is aerobic, in somewhat moro turbulent nnH in npt to the arenaceous although clastic accumulation is small. If these conditions are maintained long enough, circulation of oceanic waters will supply all the needed phasphorus or iron. It will alao supply the needed silica to produce the. bedded chort which are characteristic of both Precambrian iron-formation and bone- phosphorites. The unusual conditions namely/ a basin with impacted concretion and yet with adequate connection with an inflow from the ocean, phosphorite greatly restricted clastic influx crustal stability for a long period of time, explain the relative scarcity of bedded deposits of both iron and phosphorus. When these conditions are not fully achieve the iron is deposited in a scattering of glauconite granules and the phosphorus is precipitated in invertebrate skeletal structure or as present as a few isolated nodules or pellets (Pettijohn, 1984). Inspection of the analysis shows that generally K^O, Fe^O^, FeO and MgO follow each other and these trends iie in well with glauconite trends observed in thin sections (Parker, 1975 and Mullins and Rasch, 1985). The marginally higher iron content of the pellets may be residual after oxidation of FeS. The X-ray scans of Fe, s, Al and Si indicate that quartz, clay minerals and pyrite are randomly disseminated through some pellets which lack internal structures. The difference in the 145 element distribution patterns due to authigenic and diagenetic materials (Birch, 1980). In some of the nodules, goethite was identified, but a survey of the literature indicates that iron may be present in various forms, such as amorphous goethite and ferric-oxide gel'or as mixed oxide of Fe and Mn (Herzenberg and Riley, 1969; Glasby, 1972; Estep, 1973 and Moorby and Cronan, 1981). (1) The phosphatization took place during the iron-formations in the Bijawar basin of the study area. (2) Besides P2^5' CaO, COj and AljOg* the Fe^O^ is also an important element which is associated with all types of phos phorites in the area. The content of FejO- varies from 9.83 to 12*11% in ohfllo-i^hoophorltoa; 1.12 to 14.00% in ancondnry p)ion- phorites; 9.27 to 16.01% ironstone phosphorites and 6.66 to 14.01% in quartz-brecciated phosphorites respectively. (3) The presence of iron content in all types of phosphorite samples supported the occurrence of iron bearing minerals like hematite, magnetite, limonite, goethite, ferruginous cements, etc. (4) The presence of higher content of Fe202 in ironstones and secondary phosphorites may be due to ironstone nature and lateritization of secondary ores with epigenetic iron coatings of secondary goethite, limonite and iron-oxides,- 146 <5) The oxidation of FeO into FCjO- and higher content of Fe^O- in the phosphorites indicated the high oxidizing condi tions of the basinal-sea waters. The geochemical process took place during moist, tropical-humid and arid climatic conditions at the time of phosphatization of these sediments- The reddish- brown colour of these phosphorites may be due to association of higher content of Fe203- Most of the iron bearing minerals were originated as gel like constituents (hematite, magnetite, geo- thite* etc.) indicated the marine nearshore/conttnental marqin Ittgoonai, wctiuirtud hiyhiy oxidi/ing environiuont. (6) The presence of limonite and iron-oxide contents further supported the alteration of hematite-magnetite grains by chemical leaching during tropical to hot dry climatic conditions of the basin* (7) The oolitic ores consists of an aggregates of flattened hematitic oolites of uniform size and shape. These oolites consists of nucleus of quartz which are surrounded by successive layers of goethite and iron-oxides. These hematites in the phos phorites may be contemporaneous replacement or original preci pitates before the precipitation of apatite in these sediments. (8) It is very surprising that being a very higher contents of Fe20^ in these phosphorites, no iron-phosphate was formed in the basin. It may be possible that the hematite and magnetite iron phase was completed before the precipitation of phosphate 147 during very high oxidizing (pH > 7,5) conditions of the waters and the remaining iron content were accumulated later on in the form of secondary goethite, limonitic and iron-oxide coatings through out in the region. The secondary phosphorites samples at few places are showing the intergrowth of the ferruginous content towards the margin and it may be replacement of crys talline apatite crystals at a minor scale. This indicated that the little iron was introduced in the system at the time of secondary precipitation of phosphate in the basin. These obser vations further supported the views of Banerjee, et ?(1. (19 82) and Saigal and Banerjee (1987). (9) The iron-phosphate generally formed at the time of reduction of hydrous ferric-oxides content and the Bijawar basinal waters did not reach that pH and on the other the water was highly oxidized, which could not exist the formation of any iron-phosphate minerals in any type of phosphorites. The occurrence of phosphorites as mudstones type indicated the formation at shallow water zones• These observations supported the ideas of Stumm and Leckie (1970), Manheim, et al. (1975) and Bushinski (1946). (10) The association of higher content of iron which gave rise to reddish colour of all the phosphorites can be recalled as 'Red Beds* which were formed in a marine environment during Proterozoic time. The basinal iron-formations suggested that CO c4 14S ol + o UJ o c4 o O" Q_ /^ UJ UJ ir\ b: t o CO cc Q: X UJ o o a. .r cc o o < o X :r U O^ Q- Q_ OL U sO CM (n UJ o Q: o >- UJ Li. X ,1^ OL < o — Q V— N U. UJ 7L (n >- .J ^ o 2: o: O < u o < X UJ a: z> (O ^ U) (/» C5 w^ CC 2 rsi Hi O *- fM ro >4' t^ GQ h- 2 3 "Z- 3 m Z o 1 xr UJ if) c _l Q- Q CO 2 to < • • r~- (/) \9 Z5 in LL CO r— —r- —r- —r- —r- —r O C3 ^0 -J- 04 CO <: i2! 149 the formation of bedded phosphorites on the cratonic and/ platform regions, which are having the oolitic phosphorites and ironstones. The association of secondary silica in the form of cherts. (11) The association of Fe202, FeO and MgO follow the trend of PoOc ir^ the phosphorites as is well known in most of the phosphorite deposits. The difference in distribution of Fe-O^ content in phosphorite sarnples further supported the authigenic and diagenetic origin of these sediments in the Bijawar Basin (Pigure-13 and Tables-II and III,A). V.2.7. Ferrous Oxide JFeO) : Experimental work by Casteno and Garrels (1950) and Parker (1975) geological observations show that stability of the iron-bearing minerals is determined by the oxidation- reduction potential- At the lowest potential iron sulphide will form, at a slightly higher potential ferrous-carbonate is precipitated. Under fully oxidizing conditions the ferric hydroxides are formed. The immediate causes of precipitation in the basin are not clear (Mahabaleshwar, 1985). According to Trendell (1983) precipitation was caused by the oxidation of the ferrous-iron in the basin water by oxygen (Mason, 1966). 150 + o a: LU Ui £ Q: o ^ /N o X uj £ Q- tr in (n cc o o o X X U Q- OL 0. U tn LU o >- X. ex. o. < Q LU z: —i o < o < LL X UJ en (/) o •^ rsi ro LU OQ o Z) z Q: I I— u CO Q. < UJ o:D li. 151 Iron is one of the most abundant elements in the earth crust and few rocks indeed are iron-free. The average shale i.e. contains, 6.47% of FeO and Fe20^. Hence in the broadest sense all sediments are likely to be iron bearing (Pettijohn, 1969). As the author has already discussed in 'Fe202 distribution' that these phosphorites of the study area were originated during high oxidizing conditions in the Bijawar basin. In this way the content of FeO should be low in compared to other phosphorite deposits of India and abroad. The FeO content varies from traces to 1.63% in shale phosphorites, traces to 0,29% in secondary phosphorites; 0.21 to 0.48% in ironstone phosphorites and 0.01 to 0.29% in quartz-brecciated phosphorite samples in the study area. The low concentration of FeO throughout in all types of phos phorite samples and absence of pyrite and iron-phosphate further supported the author's above observations. The minor content of divalent iron might have adsorbed by cryptocrystalline micaceous and clayey minerals (Figure-14 and Tables-II and III A). V.2.8. Silica (SJO^) : Silicon by definition is the epitome of lithophile elements, since lithophile elements are usually defined by their affinity for a silicate phase or phases. The solubility Offlllirifl rl«ip#»n'lft on l-h'^ pM of i^.ht^ nolntion. Th*i hlcihor th«!* pH, 152 the more silica goes into solution and decreasing of pH, for instances by the addition of carbondioxide, silica is precipita ted • This process may sometimes lead to a notable concentration of silica (Gulbrandsen, 1937; Krumbein and Garrels, 1952; and Mason, 1966). Others defined that minerals which are especially resistant to chemical and mechanical break down are collected as granular materials, of these commonest is the quartz whose product is quartz-sand, showing a marked enrichment of silicon with respect to the present material (Parker and siesser, 1972; and McConnell, 1973). Silica gradually decreases with increasing phosphate content while corresponding calcium increases sympathetically (Banerjee, 1982). Silica hosted by siliceous aluminous rocks, Hirapur phosphorite shows highest silica content. Some of the processes, which are likely to have been responsible for varia tions are - (a) biogenic precipitation, (b) detrital contaminant, (c) secondary silica mobilization during regional silicification and (d) incipient metamorphism. The petrographic data of part I suggest, that factors (b) and (c) are the most dominant ores responsible for Si02 fractions in Proterozoic phosphorites (Saigal and Banerjee, 1987;and Banerjee and Saigal, 1988). Comparison of the average Central California phosphorites with the global average phosphorites reveal that these sediments are slightly enriched in SiO^ ( — 1.1%) (Kolodry, 1981). The 153 highest P^^S concentration (21.47%) is found in few samples, which significantly also contains the lowest SlOj and KjO (i.e. quartz and glauconite) values (Parker, 1975 and Birch, 1980), Silica is largely present m the form of chert which has been precipitated in the form of coherent gel. The average content of SiO^ in sea water is 3_ppm. Dissolved SiO^ exists as H2SiO^, Si02 + 2H2O > H^SiO^ Its ionisation content is - H^SiO^ > H"*" + H3Si04 K = 10"^ Evidently the solubility of silica remains unaffected at pH value less than 9. Silica associated with phosphorite have is both detrital as well as chemifial. The presence of detrital silica indicates the proximity of the basin near shore line. Cellophane itself was initially in the form of phosphatic gel which also must have contributed to the shrinkage in volume during compaction, thus developing cracks and fractures in the phosphorites. This volume shrinkage to some extent might have also added to the processes of crumpling of the phosphorite beds and at places formation of slump structure in the calcareous and arenaceous phosphate fades during diagenesis. These processes also indicate high energy condition in the zone of siliceous 154 sedin(ents while carbonate zone is more or less consistent (Khan, et al., 1981) . In the study area, (1) The association of silica bearing minerals were studied under the microscope in both primary and secondary phosphorite samples. In primary and secondary phos phorites, the silica bearing minerals are fine grained quartz, muscovite, clay but in the secondary phosphorite samples besides these minerals* the secondary silica were formed as cherts, silica-veins and cementing materials. (2) The silica content varies from 16.32 to 39,07% in shale phosphorites; 2.01 to 4.29% in secondary phosphorites; 17.98 to 23.01% in ironstone phosphorites and 18.45 to 41.32% in quartz-brecciated phosphorites respectively. (3) The individual weight percentage variations of silica supported the associations of silica bearing minerals variat/.ons petrologically as author has already mentioned. (4) The low concentrations of silica particularly in the secondary phosphorite samples may be due to continuous leaching of ores by ground water percolations mainly on the surfaces. The much higher content of silica in the quartz-brecciated phosphorite samples is self--explanatory. (5) The presence of 'carbonate' in the fluor-carbonate apatite phase may be responsible for the precipitation of silica in the very fine grained quartz and other siliceous cements- (6) The association of quartz in these phosphorites may be detrital and secondary silica as chemical C4 155 O A + o • < CM UJ tr CO o D- Ui t: t o cr o X o CL u CL •^ CL (/) t: If) or O o o X u U i CL X en C\J en 0. CL u Q: 0 o > UJ UJ ^ X 2: cc UJ U) Q_ Lrf in UJ OH CD U. CO 156 precipitates. Thus the association of detrital quartz indicate the near shore environmental conditions and with secondary silica cements supported the diagenetic origin (Figure-15 and Tables-II & III, A). V.2.9, Soda (NaoO) Sodium content is fairly high compared to any known phosphorite types from India (Banerjee, et al., 1982). The restricted sea water circulation and the apparent lack of ferruginous outwash suggest that the palaeq^salinity was high. Sodium and sulphate concentrations in the pelletal phosphorite further indicate high palaeo-salinity (Smirnov, et al., 1962). NajO is generally high in all these phosphorites but K2O remains low. Each elemental association reflects a grouping of elements, viz., structurally substituted in the major mineral apatite, adsorbed on the mineral surface or existing as discrete mineral derived from apatite during weathering. Most elements actually exist in more than one association (McArthur, 1978; Banerjee, 1982; Banerjee, et al., 1984 and Saigal and Banerjee, 1987). The alkalinity may have been locally raised due to the decomposition of organic matter and formation of ammonia in semi-restricted environment (Murray and Irvin, 1889). A stronger confinement, it seems can be used for phosphates. This argument fits the preceding observation concerning the place phosphorites in the normal evolutionary series nearest to the saline deposits, where the basin is more confined (Odin and Letolle, 1980). 157 Low Na and K contents in Jhamarkotra/ Maton, Kharwaria deposits, in contrast to higher values of these elements in Neemach Mata deposits, indicate differences in the salinity conditions during the time of their formation which, in turn, gives us scope to infer a more restricted lagoonal to supratidal conditions in the Ifeemach Mata area than the comparatively open lagoons and shoals in other phosphorite-bearing areas of Udaipur (Salgal and Banerjee, 1987), Hetrogenous but higher than normal contents of alkalies observed in many Proterozoic phosphorites could be explained by involving one or more of the following postulates - (i) higher salinity conditions during the formations of these phosphorites indicating supratidal concentrations, (ii) high carbonate subs titution for phosphate ia apatite lattice, (iii) like contamina tion by clay/mioa/foiaHpar, (iv) occurrenco of aiknlies in some discrete phase independent of apatite, and (v) insignificant weathering effects (Saigal and Banerjee, 1987), The presence of high amounts of alkalies analysed in these phosphorite seems to have been contributed by clay minerals which are common in these phosphorites (Saigal and Banerjee, 1987). The Na, Sr, CO^ and SO- contents of carbonate-fluorapatite may be used as a crude 'weathering index' for phosphates. Unweathered Moroccan carbonate- fluorapatite contains about I.6O96 Na20; 2.6% SO^; 8.3% CO- and 0.23% Sr. Concentrations are lower in weathered samples. The -:r •f O CO •158 u cr o in /N UJ o O cr X iX o £ a. in. (/) cr o O < ao. X X u oo en a. a. o cr yr^ >• UJ GQ cr z: a. < o O Q V— N u in t— ^ 10 -J o•z z cr < u o < X LU cr 3 tfl in tn H-l a u m LL »- (N m o (T) 3 Z 2 1 o LU I— —J Q. CD cr < >— (/7 en Q «\ hco U? UJ cr sS» 3 O i^f> u. —r- —r- —f— T— —r- O ^0 03 so c4 6 high limiting concentrations may be characteristic o^ the original composition of apatite in other deposits, (Gulbrandsen, 1960, 1970; Bliskovski, et al•, 1967; Lehr, et al., 1967; Tooms, et al., 1969 and McArthur, 1978,b). The constituent such as SiO^. ^"*-2^3' "^^^2' ^^2^ ^°^ ^^ ^^® associated with silicate and other detrltal minerals (McConnell, 1973). In the study area - (1) the NajO content varies from 1,05 to 2.65% in shale phosphorites; 0.07 to 0,89% in secondary phos phorites; 0.21 to 0.31% in ironstone phosphorites and 0.19 to 0.52% in quartz-brecciated phosphorites. (2) The Na20 content is almost high particularly in the primary phosphorite samples and on the other hand the low content in secdndary phosphorites may be due to weathering of ores by ground water circulation. (3) In primary phosphorite samples, the higher concentrations of NajO nxay be due to occurrence of micaceous/ clay and feldspar minerals and palaeosalinity of the basinal waters and litho- phlllc nature of Na20. (4) The higher content of NajO Indicated the restricted circulation of basinal waters and palaeosalinity of Bijawar basin. (5) This element may'be partly substituted in the apatite crystal lattice or adsorbed on the minorol nurfocoo. (6) The association of alkalies indicated the origin of phospho rites in the more alkaline environment and shallower conditions of the basin. (7) This also indicated that the higher alkaline (Granites, etc.) sAurce may be very near to the phosphorite formations and supratidal conditions of the basinal-sea (Figure- 16, and Tables-II and III^A)- 160 V.2,10, Potash (K^O) i Wedepohl (1970) reported that Na and K are monovalent and have higher chemical affinity, K"*" can be very easily replaced by Na in an ordinary conditions as they are sympa thetic to each other. Generally^ it is to be seen that concen tration of K is always higher than of Na in almost all the samples analysed. As shown in part I of the paper, the Hirapur phosphorite in a residual type of deposit and in such phosphorite, it was imperative that highly mobile elements like Na and K should be present any in small anounts. Hence, high concentrations of NajO and KjO in Hirapur phosphorite seem to defy the geochemical rule and are intriguing in the first instance, A significant increase in the F and K content and marginally high Na content in pelletal phosphorite clearly indicate a hypersaline supra- tidal type of environment during the formation of Cumbum pelletal phosphorite. In course of time, the sedimentational water became saturated in respect to various major and trace elements due to semi-evaporative situation of the basin. Because of their easy of availability, most^the elements were preferentially enriched in the pelletal and intraclastic phosphorite grains agitating at the bottom of shallow, protected, barred basin (McArthur, 1978; Banerjee, et al., 1982 and 1984 and Saigal and Banerjee, 1987 and Banerjee and Saigal, 1988). 16^1 The place of phosphorites in the normal evolutionary series nearest to the saline deposits when the basin is more confined (Odin and Letolle, 1980)• Each elemental association reflects a grouping of elements, viz., structurally substituted in the major mineral apatite, adsorbed on the mineral surface or existing as discrete mineral derived from apatite during weathering. Most elements actually exist in more than one association (Banerjee, 1982), Inspection of the analysis shows that generally ^20, Fe^O^/ FeO and MgO follow each other and there trends Jcie in well with the glauconite trends observed in thin section (Parker, 1975) • The higher concentrations of litho- phile elements (A1# Mg, K) in the rocks is due to the presence of terrigenous minerals (feldspars and clay minerals) in the sediments prior to lithification (McConnell, 1973; Birch, 1980 and Mullins and Rasch, 1985), In the study area, (1) the K2O content varies from traces to 1.78% in shale phosphorites; 0.13 to 0.53% in secondary phos phorites; traces to 0.74% in ironstone*phosphorites and 1.01 to 2.45% in quartz-brecciated phosphorites. (2) The K2O content is almost similar like that of Na^O in all the phosphorite samples but the K2O content is very high in shale and quartz-^brecciated phosphorite samples. These content may be high due to the presence of micaceous, feldspars and clay bearing minerals. (3) On the other hand, the low content in ironstones phos phorites may be due to poor association of detrital constituents CM CO CM 162 CM ' UJ Loo A 0 L^ Ui UJ 10 H3 h- 0 Q: X L^ 0 a0 : Q. if) < in 0 0 a X X U oQ. a. QL 0 if) UJ Ocvi o >- UI a: CO X < 0 Q k— N Ixl Z (/) >— -J 0 z cr cs < u 0 < X UJ Q: 3 O cn tn »-* 0 •^ z *- (N CO ^ o m — cr D CD 00 Z cr I- t— U w AO _J CL Q in 2 r+:^ < -a' CO * • UJ m cn CD 04 r- —7 1 1 r- —n —r —I— -3" CNJ O 00 U? 00 CM C4 O oj OJ — — O O 6 6 o, 163 and high ^^2^3 concentration. The secondary phosphorites may have lost the K2O from the rock constituents by lateritization. (4) The higher content of K2O like that of Na2 0 indicated the palaeo-salinity* supratidal# hypersaline, shallower and restric ted circulation of water within the basin, (5) The higher concentration of KjO also further supported the presence of high alkaline source (Granites,etc. ) in the area near the phosphatization site; structurally substitution in the apatite crystal lattice and adsorbing by cryptocrystalline quartz and clayey minerals (Figure^l? and Tables-II and III A). V.2.11. Magnesia (MgO) : + 2 The uptake of Mg by clay minerals is proposed to + 2 explain Mg depletions in marine interstitial waters (Sholkovitz, 1973). The higher concentrations of MgO in sea waters, however, may inhibit the precipitation according to Martin and Harris (1970) and Birch (I960); Mullins and Rasch (1985). However, Burnett (1977) found on the Peru-chile shelf that only these sediments which contained dolomite, chlorite or sepiolite also contained detectable apatite. He believes + 2 that the diagenetic reactions that take up Mg ions would be favourable for the precipitation of apatite. MgO shows moderate enrichment possibly also owing to goethite seavanger activity in these samples (Parker and Siesser, 1972). 164 Magnesium content in recent CaCO^ sediments varies between 3 and 5 times that of MgCO^ in weight percentage (Chave, 1954). The magnesium content increases with increases age (Chillingar, 1956 and Ronov, 1959). MgO is usually considered as being entirely lithophile in character and this is borne out by its presence in ferromagnesium silicates in all the stony and stony iron-meteorites (Mason, 1966). Bremner (1975) pointed out that direct precipitation of. apatite is inhibited in these mudfl by their rolfitlvely high MgO content nnd low tompornturo (ll'^C). The phosphates are having binary compounds of Pb or Ca with Cu, Zn, Mg and sometimes Mn (Betekhtin, 1959). Inspection of the analysis shows that generally K2O, ^6203/ FeO and MgO follow each other and these trends tie well with the glauconite trends observed in thin section (Parker, 1975). (1) It is well known that magnesium is having chemical affinity with calcium in the gaologicol environmont. (•2) The apatite is a calcium-phosphate mineral with additional anions like F, CO-, OH/ CI and sometimes 0 also. This way the association of magnesium in this mineral is must. (3) In the study area, MgO varies from 0.2 0 to 1.03% in shale-phosphorites; 0.09 to 1.60% in ironstone phosphorites and 0.39 to 1.01% in quartz-breccia phosphorites and traces to 0.41% in secondary phosphorites. CM 165 CN cvi o + o • < CO A UJ -r o UJ (/OL> 1— fu- o .in X 5 a: CL. o ill1 • 1 p o \— Q_ Q- - J- if) tn < en cc Xo oX CJ Qo- Q- Q_ CJ CO lf\ UI CC U- o >- Ui UJ O cr CD a. < O m »— M LU oz m t— —1 o 2 Q: => 2 < O < 2 I- X oLU r) t/) in 1-a^ C3 I ^ -— rsi r^ CL •- CO to oo LU in cr CD fcO CM r- —J— —r- —(— O 00 •J- ot O CO o CM 6 O <^ 166 (4) The presence of MgO in all types of phosphorites are low and more or less similar. (5) The occurrence of magnesium may be due to ionic substi- + 2 +2 tion of Mg by Ca in the apatite during the marine, oxidi zing conditions of the bpsin. (6) The minor content of magnesium may be due to adsorption by fine grained quartz and clay minerals and in the huge masses of iron. (7) The low to moderate content of MgO in the phosphorite samples indicated the goethite seavanger activity and non- calcareous sources of the deposit. (8) The presence of MgO in these samples further supported the diagenetic origin. (9) The higher content of MgO particularly in the primary phosphorite samples indicated the direct inorganic precipitation but in secondary phosphorites further supported the diagenetic origin (Figure-18 and Tables-II and III A). V.2.12. Titania (TiOp) s Titanium is a lithophile, clastophilic element with close affinity to volcanic, igneous and terrige nous sedimentary rocks. It is a less mobile element as compared to others. Titanium in the form of insoluble heavy minerals (ilmenite and rutile) may concentrated in certain residual 167 Bediments. Most of the elements are found in tho clay fraction of the hydrolysates sediments• In marine oxides and residual sediments, it is very sparingly represented, the amounts being proportional to the quality of admixed clay. Practically, no titanium enters into oceanic water as a solute, owing to the prohibitic ionic potential. Titanium is therefore not found in evaporatic sediments (Mason, 1966). The titanium contents in Pithoragarh and Birmania phosphorites varies from 0.01 to 0.5% and 0.13 to 1.75% (Khan, 1978 and Viqar, 1981). The elements depleted in phosphorite (B, Co, Ga* Hg, Li, Sn, Ti and Zr) fall mainly two categories. Some occur in rela tively stable and insoluble minerals - Ga in clays, Zr in zircon, Ti in ilmenite and rutile are therefore richer in highly detrital shales and in largely chemogenic phosphates (Altschuler, 1980). The elements Al-K-Ti-Zr consistently of clay groups and may be due to substitution and as adsorbed onto th<=? clay surfaces (Howard and Hough, 1979; Rasmy and Basily, 1983)• The consti tuent such as SiOj, Al2^3' ^^^2' ^^2^ ^^^ ^2^ ^^^ associated with silicate and other detrital minerals. Some magnesium, alkalies as well as silica and sulphur (SO^) are known to be incorporated in phosphate lattices (McConnell, 1973). * (1) The Ti02 content is almost very poor in compared to other major oxides in all types of phosphorites in the study area. It varies from traces to 0.95% shale-phosphorites; traces oi 168 /^ + O • <3 o 04 U "21 -00 UJ LU £ o r+- X 0 LU o o Q- a. a. VO 01 ^ P tr tn < o o o X o 10 CL X u LU LL (/> a. u o a. cr 0 X >- UJ m a. cr m 2 < o N Z) z Q I— 0 u 2: (/^ I— -J O tr z o < 1— < u OJ 1 X u C3 LU GO I/) (/) *-* _l . — QL Cd *- fs m 2 CO 0 < Q CO * • UJ cr ID • in U_ -4- cO Ol 169 to 1,00% in secondary phosphorites; traces to 0,50% in iron stones-phosphorites and traces to 0,77% in quartz-breccia phosphorites. (2) The presence of Ti02 in the phosphorite samples confirmed the lithophilic and,clastophilic nature and association with terrigenous sediments* (3) The low content of titania indicated the less mobile nature and accommodation in the clay, iron and phosphate bearing minerals on to minerals surfaces as adsorption. (4) The low concentration qjE-Titania may be due to mild leaching of ores but in one -sample of secondary phosphorite it is slightly high. (5) It may be possible that at the time of remobilization and re-precipitation of phosphate in the sedimentary marine, shallower environment, the TiO^ might have followed the same trend alondwith Po'^s* (6) The presence of very fine grained of few rutile grains might have raised the TiO^ content in these phosphorites. It is also possible that the minor content of Titania might have incorporated into the apatite crystal lattices (Figure-19 and Tables-II and ill,A). 170 V» 2 >13, Manganese-Oxide (MnO) t This element has high geochemical mobility and thus differ from titanium and aluminium (Mason, 1966). Walker and Parsons (1924) reported 3.0 to 8.8% of MnO in the phosphorites of Tatarinov. Quensell and Yakshin (1937) on the other hand noticed 3.0 to 8.80% of MnO in apatites from Tatarinov phos- t phorite deposits. Manganese like iron is enriched in hydrolysates residue formed during lateritic weathering and is concentrated mostly in oxidate sediments. It is generally absent in sediments formed as a result of solution of reprecipitation/ as is evidenced by very low Mn content in Birmania phosphorites and may be the product of reprecipitation (Viqar, 1981). MnO usually requires highly oxidizing conditions to precipitate (Krauskopf, 1959 and 1969). Mn, marine deposition chiefly in the form of the dioxide, have been formed under shallow-water conditions and in deep sea sediments, where it is widely distributed as nodules. The asso ciated rocks are shales, limestone and less commonly, sandstone (Hewett, 1928). The relatively low content of Mn (145 vs. 1,230 ppm) most likely signifying a paucity of Mn-oxides associated with Central California phosphorites (Mullins and Rasch, 1985) compared with Altschuler (1980) average phosphorites. 171 Low MnO values for Hirapur phosphorite is explained by the leached and secondary enriched nature of the deposit (Banerjee, et al., 1982; Saigal and Banerjee, 1987). Mn concentration is low in stromatolitic phosphorite in comparison to pelletal phosphorite. Its concentration decreases signifi cantly in phosphate concentrates suggesting its affinity for the associated carbonates. It is however, intriguing that the apatite o£ the pelletal phosphorite which contains only small amounts of free carbonate, has the highest Mn content and consequently the speculation of carbonate-Mn linkage appears invalid for these phosphorites. It is possible that Mn is either present as adsorbed ion on the surface of apatite and/present in some other discrete mineral species of similar paragenesis not identified in the present investigation (Banerjee and Saigal, 1988). Moreover, Ba, Cu, Mn, Ni and V listed as impoverished in sea water have normal abundance in phosphorite (Tooms, et al.# 1969). In some of the nodules, goethite was identified, but a survey of the literature indicates, that iron may be present in various forms, such as amorphous goethite and ferric-oxide gel or as mixed oxide of Fe and Mn (Moorby and Cronan, 1981; Estep, 1973; Glasby, 1972; Herzenberg and Riley, 1969). CO 04 17E CM -»- o - A O a: o UJ U tn CO Q: o UJ O o Q- X Lr*- a: otn • a: X cr u Q_ CD in < O o *- M ^ _ c (/) I— -T 2 < o O < X U UJ en I/) a: z) CO m LL. oi 2 o •— rsi CO Z) 2 2 •^^ 1 O LU 1— O _j 3 Q. m VD LU m Ia:D CD LL tO c\j 173 In the study area - (1) the manganese content is also poor and similar like that of titanium, magnesium, ferrous- oxide, etc. It varies from 0,03 to 0,39% in shale phosphorites; traces to 0,39% in secondary phosphorites, traces to 0.13% in ironstone phosphorites and similar in quartz-brecciated phos phorites, (2) Much variation of MnO content in these sediments supported the higher mobile nature of manganese. The low concen tration of MnO in the secondary phosphorite samples may be due to leaching of the ores, (3) The association of MnO in these rocks indicated the high oxidizing environmental conditions of the basin. (4) It further supported the marine and shallower conditions of the sedimentary basin. (5) The MnO may be partly emplaced in the apatite structure and as/adsorbed on the mineral surfaces of clay, phosphate and iron bearing minerals. (6) The low and normal abundance of MnO in these sediments indicated the ancient connection of sea with basin at the time of formation of Hirapur phosphorites (Figure-20 and Tables-II and III A). V,3. GEOCHEMICAIi RELATIONSHIPS BETWEEN MAJOR ELEMENTS : In the study area-an attempt has been made to determine the geochemical behaviour of phosphorus in relation to other elements on the one hand and also the mutual geochemical relationships among the elements other than Phosphorus. 174 The study helped greatly to bring out reasonably the geochemical environment at the period of deposition of phosphates in the Bijawar Basin that hosted a thick sedimentary sequence of phosphate bearing rocks. V,3.1, Relationships of PQOC with various Oxides s V»3,l.l. P^O^ vs. CaO : Krumbein and Garrels (1952) and Nathan and Sass (1981) believed that pH of the water is most important factor in the precipitation of both CaCO^ and P205« They have also observed that an increase in pH caused precipitation of CaCO^ and a slight decrease in pH initiated deposition of ^2^5' According to Ames (1959) carbonate-fluorapatlte is the end product of a diagenetic replacement process in which the dissolved phosphate ions substitute for carbonate in calcareous materials. Krauskopf (1967) on the other hand believed that precipitation of CaCO-. was favoured where water is warm and CO2 was lost by evaporation or photosynthesis. A positive correlation between CaO and P2*^5 ^^^ been observed in the apatites of Sherrin-Creak phosphorites (Howard and Hough, 1979). Banerjee, et al. (1982) also found a positive correlation between the two oxides on the basis of their 175 distribution pattern in apatite structure in the phosphatic rocks of Hirapur-Bassia area, district S&gar, M.P. Kinsey and Davis (1979) suggested that clacification is Inhibited where there is a high concentration of phosphorus. According to Banerjee (1979), there are many evidences for the co-precipitation of carbonate-phosphate in rhythmic alteration of calc-phosphate and silica saturation cycles and as differen tiation is prominent between day and night formed phosphate- calcium layers and noctural silica saturated layers. He found also that differentiation amongst c:alcium and phosphorus layers is certainly diagenetically controlled and shows sympathetic relation between the two. Rao et al. (1987) observed that in Vattaluru phospho rite with concentration of ^2^5 ^^^^ 30.28%, the relatively higher ^2^5 zone is confined to lime rock zones though there is no progressive increase of in ^2^5 with lime. Banerjee, et al. (1982), after comparing the variations in the composition of carbonate-apatite in the less-weathered and more weathered phosphorites of Hirapur areas as reflected by their normalized structural concentration values arrived of a that the values could be taken as a measure of the chemical ingredients of the depositional waters at the time of the phosphorite formation. 176 Cook (1972) and Khan, et al. (1981) also observed a sympathetic relationship between lime and phosphate ions in the phosphorites of Australia and India. They found th;:jt the -3 +2 (P0-) ions have been almost completely used up by Ca ions to precipitate calc-phosphate in high grade ores and in low end medium grade ores, some of the calcium left after reacting with phosphate ions might have precipitated as CaCO-, and in such cases the value of 'Loss of Ignition* (LOl) went up. Further, residual calcium is supposed to have been incorporated in the formation of insignificant silicates. Minerals of the apatite series have the general formula, Cac (^04)3 (F, CI, OH), According to McConnell (1938), Krishnan (1942), Dana (19bl), Altschuler and Co-Vorkers (1952), Heinrich (1954) and Altschular (1980), the elements which are-believed to be capable of substituting with the lattice of apatite are (i) Ca grouped as followa. For example ~/C, Mg, Na, K, Mn, Sr, Ba, Pb, U/ rare-earths;o'3for phosphours - Si, s, C, V, As;oiifor oxygen - F, OH. Cook (1972) and Parker (1975) held that essentially there are two groups of major elements - 1) those which are located predominantly within the apatite lattice (CaO, Po^c' NajO* C02# F), and 2) those located outside the lattice in apatite either of detrital origin (SiO^, AI2O2, K2O, TiO^) or introduced by weathering Fe^O^, MgO(?) , MnO-r They reasonably 177 anticipitated that a positive correlation will exist between ^2^5 ^^^ elements located within the apatite lattice, whereas a negative correlation will be apparent between P2^5 a^<^ elements located outside the lattice, According to Krauskopf (1967) when a solution of Ca+ 2 is added to a phosphate solution, the immediate precipitate is 080(^04)2 ^^ CaHPO,, depending on the pH. Both of these compounds are known as minerals, but they are very rare. The chemistry of calcium-phosphate is complicated by the ability of this substance to react with other materials in solution to form a still more Insoluble compound called apatite, which is the most abundant of the phosphate minerals. The most familiar of the apatites is flaorapatite, whose formula may be written either[ Ca^lPO.) ]- CaF2 or Ca^CPO-)^?. This is the common apatite of igneous rocks and is also an important constituent of phosphatic sediments. In the study area, ^o^S ^^^^^ ^ strong positive correla tion with CaO in all four types of phosphorites which indicated the following genetic aspects of these sediments t- !• The origin of phosphorites may be diagenetic in which CO^ might be removed by PO. before the precipitation of phosphorite during high oxidizing conditions of the basinal water which gave rise to carbonate-fluorapatite as an end product. 2. The precipitation of phosphate may be directly from basinal-sea waters• rO (O 178 o O O <30 o ^ \ ^ o o.^ °\ k-T o o ^ c CM 0) \ + o • x «0 6 UJ vo \ 6 c o \ NT o Q. UJ UJ 10 \^ k— »-* O + 6 JS. Q: X UJ £ s Q. OH 6 N O < a ITJ X 3: u to S iO 2 £ CL Q- o s (n UJ o tr X >- UJ CD (X m LL. < o Q vz N c4 UJ Z to t— Q: 1 o ^ a < o CD < X LJ PC :D t/1 I/) »M rt rv> o a o^ O o • \ <3 J- .10 c • O TO . in flj ^ CM o OJ -O <1 \ CM \c Ift C . o 0 -10 a: 1 1 1 ( 1 1 1 1 —I O 0 in o lO if) O un o est ?> vJT fO 9.r<> <^N P,cvi ^ 6 in O LL Qf^ 179 3. The calcium-phosphate (apatite) layers may be a product of rhythmic alteration by silica and carbonate saturation cycles in the basin* 4. Besides calcium-carbonate-fluorapatite phase the asso ciation of other major oxides in these phosphorite samples indicated the nature and extent of catlonic substitution. 5. The normal/weak progressive relationship between these two oxides in the few samples of secondary-phosphorites may be due to mild weathering. 6. The sympathetic relationship indicated that (PO.) V2 ions has been completely Used by Ca ions to precipi tate calc-phosphate in high grade ore in the area. 7. The sympathetic relationship further confirmed the internal crystal structure of apatite in which the CaO and P2^5 ^^® located inside the crystal lattices of apatite (Figure-21). V.3.1.2. P2*^5 vs. CO2 s Many authors have proposed that the charge loss on 2- 3- substitution of CO^ for PO. is partially balanced by the replacement of Ca"** by Na"*" (Alder, et al., 1963; Youssef, 1965; McClellan, 1980; Axelford, et al., 1980 and Manheim and Gulbrandsen, 1983). 180 According to Blackwelder (1926); McConnell (1938. 1962, 1960, 1970 and 1973) the COj radical is present primarily as a substitute for the phosphate (PO^)"^" radical. The work done by Altschular, et al, (1953); Ames (1959); Rooney and Kerr (1967) and McClellan and Lehr (1969); Stow (1970) also supports this view. Depending on the degree of substitution of phosphate for carbonate, the mined phosphate ores with equal amount of apatite could differ as much as 10-13% of P^Oc (Hyin and Bliskovsky, 1984). As the apatite '002* contents of these iron rich rocks support the sympathetic relationship between the fapatite' CO2 content and the F/P^O^ ratio (Rao, et al., 1967; Parker and Siesser, 1972). Gulbrandsen (1970) associated a regional increase in apatite, CO2 content with a regional increase in the water temperature of the original environment and hence the high CO2 values for the Agulhas Bank phosphorites may imply that those apatites formed in waters that were consi derably warmer than those in which Phosphoria apatites were formed. CO2 plots show a wide scatter and random correlation suggesting extensive leacRing during weathering. The Bijawar phosphorites show characteristics of an epicontinental sea with restricted and very shallower marine environment of formation along some shoals, which existed during the iron rich Precambrian 181 times. The phosphorite of the Hirapur-Bassia area show extensive LeadRing of carbonate and phosphate minerals during episodes of weathering (Banerjee, et al«# 1982), COj shows a weak and crude linear relationship with ^2^S ^^ ^oat apatites, but in more weathered rocks, the COj content is higher, possibly due to secondary vein-filling by calcites and in this, the plot deviate significantly from linearly. This linear random correlation also indicates variable leading (Roger, 1922K LeGeros, et al- (1967) showed that increasing substitutibn of CO, in the apatite lattice promotes increasingly equidimensional crystallites, as well as decreasing crystals and lattice dimension. The tendency toward I poorer crystallinity is partly compensated by the crystallizing effect of fluorine in the solution (Simpson, 1966). Thus, the optically Isotropic habit of the Blake phosphorite, like many marine phosphorites, may be explainable by its high CO- substi tution in the apatite lattice, which under low-temperature conditions leads to formation of an aggregated mass of well- crystallized but minute and equidimensional spherulites (Manheim, et al., 1980; Manheim and Gulbrandson, 1983). Fisher (1873); Murrary and Renard (1891); Miller (1896); Collet (1905); Murrary and Philippi (1908); Goldman (1922); Power (1926); Cayeux (1934); Trask (1939); Wagaman (1952); Graham and others (1954); Gulick (1955); Redfield (1958); Ames (1959); Sinpson (1964); LeGeros (1965); Degens (1965); Gulrbandson (1960, 1966, 1969; LeGeros and other (1965, 1967); Pevear 182 (1966, 1967); Krauskopf (1967);Summerhayes (1967, 1970); Patwardnan (1971); Vaiaiya (1971); Berg (1972); Degens (1974); Mareuso and others (1975); Patwardhan and others (1975); Verma and others (19 75); Parker (1975) and Srivastava and others phosphate (1978) were established that the^rich rocks were formed by replacement of CaCO^ by calc-phosphate. Later, an alternative theory ofor the formation of phosphorite was proposed by Kazakov (1937) who favoured direct inorganic precipitation of apatite from phosphate saturated sea-water« Support for both theories came in from the field and laboratory (Dietz, et al,, 1942; McKelvey, et al., 1953; Cheney, 1955; Cheney and others, 1959; McKelvey, 1959, 1967; Ames, 1959; Sheldon, 1964; Cressman and others, 1964; Maughan, 1966; Summerhayes, 1967); whereas theo retical evidence (Simpson, 1964; ^Sheldon and others, 1964; Yochelson, 1968; Gulbrandsen, 1969; Israili, 1976,a, b, 1978) also indicated that a dual mode of formation was likely. Increase of pH causes precipitation of both calcite and apatite; when both are co-precipitated, the calcite/apatite +2 -3 -2 ratio will be higher; since Ca , PO^ and CO^ all have sinqle valanco ntnt«n, rhorg^n in Eh cnnnot produco nopnrntion into carbonate and phosphatn rich layers; hence the individual enrichment will have to take place within a narrow pH range, -2 Relative to CO^ , the Ca^ (^04)9 ^^ less soluble (the solubility 9 30 product of CaCO-j is 4 x lo" as against 1.3 x 10" for Cao(P04)2 183 Hence, in the pH range 7.0 - 7*5, ^93(^0^)2 can first preci- pitate while the CO-^2 remains in solution so long as the pH is buffered in that rtnge. When the pH increases to 8, CaCO^ will precipitate (Heinrich, 1954; Garrels and Christ, 1965; Krauskopf, 1968; Chakrabarti, et al., 1973; Nathan and Sass, 1981). In the study area/ CO2 shows random and linear but progressive positive relationship with P^^S ^^ ^^^ four types of phosphorite samples. This relationship of these two elements indicated the following author's observations regarding the phospho^genesis of these sediments 4- 1. During phosphatizatlon the CO^ content might have replaced by PC. within the basin and this reaction + 2 +1 partly balanced by Ca by Na and controlled by crystallographic control on the degree of carbonate substitution, 2. There is no biogenic control at the time of phospha tizatlon of the phosphorites because there was no life in the area- 3. The random and/linear relationship may be due to mild weathering of these phosphorites. 4. During phosphatizatlon most of the COj content lost by releasing of temperature and pressure of the oceanic waters by upwelling currents from colder to warmer 184 regions. The minor contenl: of CO2 and this type of relationship indicated the warm and shallower conditions of the Bijawar basin. 5. Thio rolntlonnhlp rnny bn duo to apoedy rr»movnl of PO^, Ca, Mg and CO^ ions from the shallower surficial marine waters during the prolonged day light hours and changing of basinal waters chemistry during the night• This supported the pH fluctuations periodically leading to CaPO- and silicon saturation cycles. 6. This relationship indicated the extensive leading and episodes of weathering and show characteristics of an epincontinental sea with restricted and very shallower marine environment of formation along some shoals which existed during the iron rich Precambrian times. 7. This relationship show the pseudoisotropic/isotropic nature of apatite which is generally formed during low temperate conditions in which very fine grained, minute, equidimensional spherulities aggregations were formed. 8. It also supported the hypothesis of direct inorganic precipitation of phosphorites by means of upwelling currents- 9. The occurrences of thin bands of phosphorites indic^^ted the narrow range of Eh and pH of the Bijawar basinal waters. 185 10. The mutual ionic substitution of PO^ by CO3 indicated the flbundont prosence o£. these ions in sea-water and probably used as an indicator of palaeosalinity (Figure-22). V.3.1.3. P^O^ vs. Al^O^ The Al^O^ content varies from 1.79 to 3.15% in the phosphorites of the study area, the diagram shows a negative between the two constituents. Like iron, aluminium also decreases with the increase In Pn^S concentration. The irregular distri bution of crandallite is also due to differential weathering of shaly apatitic phosphorites. The carbonate fluorapatite —) crandallite (Ca) transformation in these phosphorites appear to be in their early stages, compared to phosphorites of the Sontai area of the western Bijawar basin, where minerals are of more advanced weathering stages •—^ Millisite —> wavellite are also recorded. It is possible that the petrogenetic sequence would have been the same as those identified in the Sonrai area. West Senegal, parts of Florida, Rumjungle area in Australia and parts of U.S-S^.R., provides the Hirapur-Bassia basin was not protected from the onslaught of weathering for a considerable time after they were lithified and uplifted (Banerjee, et al., 1982). o *°,186 o > in 'cr O in Q.^ \ vS \0 o O c " to a; \ a; in 6* ^ o ^ 4 O • <1 ' CN \ . ^ CL \ — x: o "~o. \ c UJ •<^ ~ o \ + m 4-« (C O UJ 111 CL * 6 *s V;^ i— to r\ —1 r- <« 1 v-/ cr cr cr o in in in -*-"^ o o X o in o in O ci UJ Q- Q_ Q. ^ cr X Q: en a. < O Q t— NJ lij Z 0^ *— _i o z cr < u o < X LU Q: 3 in if) 1—1 C3 ^ fN CO 187 In the study area, Al^O^ shows a wenk negative relation- Bhip with ^2^5 *^^'' ^^^ ^^^^ types of phosphorite samples which gives the following informations J- 1. There may be mutual ionic substitution in between Al by Ca"^^ in the apatite lattice under high alkaline conditions of the basinal waters. 2. The AI2O3 rnay be adsorbed in hydrous aluminium- silicates, ferruginous and clay minerals which is high in P^Oc content. 3. The irregular distribution of crandallite (Ca Al PO^) CO3 particularly in secondary phosphorite samples indicated the hidden leaAing/weathering of ore in which small amount of Ca was replaced by Al during remo- bilization and recrystallisation by means of the ground water circulation and sea-waves, tides and currents in the Bijawar basin (Figure-23). V.3.1.4. ^2^5 ^'^* ^2*^"^ Of the 11% volatiles in the apatite less than half could be accounted for by COj in the samples. Water forms the other volatile released when the apatite is heated. This water is probably as present in the crystals as hydrogenious + 2 —3 (H^O^) substituting for Co and (PO-) respectively (Simpson 188 1964). The wide variations in apatite observed in nature is related to the following substitution (Heinrich, 1954). For PO4: SO4, AsO^, VOA, CrO^, Si04, AIOA , CO3, OH. According to Betekhtin U95S) and Burnett (1977), the proposed model of phosphorite formation involves inorganic precipitation of apatite within pore waters of anoxic sediments and subsequent concentration of the apatite by physical process. They also noted that apatite precipitation is favoured within the sediments by the high phosphate concentration in the interstitial waters by the availability of suitable nucleation sites and by + 2 diagenetic reaction that remove interferring Mg ions from the pore solutions. They also believed that the concentration of apatite into indurated phosphate nodules was brought about by winnowing and reworking processes, possibly in response to a change in the sedimentary environment caused by eustatlc sea level fluctuations or tectonism. In the study area, the P^O^,shows a weak but progressive relationship in all types of phosphorite samples. This relation ship indicated the minor scale substitution with PC. in the apatite crystal lattice in which carbonate-fluorapatite is the final phase. In secondary phosphorite samples the relationship is slightly better than that of the primary phosphorites. It may be due to chemical leaching/weathering of the ore by water Itself in which the water molecules were also fixed in the apatite lattices and cryptocrystalline paragenesis of iron and 189 clay minerals. This relationship further supported the direct inorganic precipitation of primary phosphorites by various physical and chemical processes. The processes of winnowing and reworking of primary shale phosphorites and formation of secondary phosphorites may be due to possible change of sedi mentary environment caused by eustatic sea level fluctuations or to same extent tectonic disturbances (Figure-24), V.3.1,5. P20^ vs. ^2^ « Gulbrandsen (1966 and 1969) has shown, there is an approximately 1 t 1 relationship between the atomic ratio of S to Na in the Phosphoria phosphorites and he has interpreted this as reflecting a coupled substitution in the phosphate mineral of Na and S for Ca and P . Apart from trace amounts of pyrite and feldspar, there are no S or Na minerals in the Agulhas phosphorite and it is therefore suggested that the S and Na values determined for these rocks reflect substi tution effects in the francoiite (Parker, 1975). Both the alkalies (sodium and potassium) in the phosphorite deposits of the Georgia basin. Worth Australia, and most of the Indian phosphorites have reported random correlation between Na«0 and P^O^, The random behaviour of both the alkalies in phosphorites has been explained as due to glacial and arid to humid conditions 190 cs :5 C O a. .E c .2 + o • < Of UJ CD a: LU UJ £ tr O o X UJ 0. >— £ (/) O o o X D- Q- 0X. u if) UJ O oc X LJ GQ Z CN^ a. m o N HI »-^ 2 z < o < 3 ^ X _ Q: i-t C3 jn in o) 5^ C CU (0 o a. -^ IUc) 00 c 6 o ^ 4-* 6 "a! -T CC 6 uc CM CN ' 6 6 0 LL y» or 19t at the time of deposition which enhanced the rate of weathering prior to deposition by Simpson (1964); Ronov, et al. (1965) and Howard and Hough (1979), Lehr, et al, (1968) have shown that the crystallite size of the apatite decreases with increasing carbonate, sodium and magnesium substitution. Although the reasons for such relatio ship are not readily apparent, it seems probable that the concen tration effects of Na, Mg, and CO3 responsible for the highly substituted apatite structures may inhibit crystal growth. According to Srivastava and Banerjee (1981) a very small range of crystallite size values indicating that the apatite in these phosphorite is a highly substituted variety of fluorapatite. In the study area/ there is a randomly positive rela- of tionship in all between the two constituents^phosphatic rocks, + 2 +1 explained as may be due to minor substitution of Ca by Na in the apatite lattice during phosphatisation. This relationship is an indication of arid to humid climatic conditions at the time of deposition that probably enhanced the rate of leaching/ weathering prior and/just after the deposition• The presence of ^^2^ in the phosphorites further supported the substitution of various elements during alkaline marine conditions in which the crystallite size decreased. This relationship indicated the deposition near the sea-shore with high salinity. This relation ship further supported the idea that ^^2^ occurs within the apatite crystal lattices (Figure-25). 19E V.3.1.6. P2O5 vs. K2O s It could be anticipitated that a negative correlation will be oparcnt between Pn^^B ^^^ other oxides which ore locatcO outsirie (Cook, 1972). The pK of the basic solution, the ^^2^^3 apatite contains/ approximately five times as much alkalies as potassium carbonate-apatite (Simpson, 1964). In the study area, the K^O shows a progressive random but negative relationship with ^2^5 ^" primary phosphorite samples and weak positive and linear relationship that in secondary phosphorite samples. The negative relationship in primary phosphorite indicated the presence of minor amount of K2O in the outside of the apatite crystal lattice and on the other hand the positive correlation in secondary phosphorite types may be due to solution, re^precipitation, leaching and/ weathering of ore in an alkaline, marine, shallower water of the Bijawar basin (Figure-.26) . V.3.1.7. P2^5 vs. Fe20^ : Most phosphorite are relatively low in iron and therefore, it has generally been concluded that ironstones and phosphorites do indeed have little in common. But while 193 phosphorite may be low in iron (the average FejO- cont'^^nt of sedimentary phosphate rock as calculated by Smith and Lehr (1966) is 0,63%. The iron-ores are, however, not necessarily I6w in phosphorus though McKelvey (1973) gives the average PjOc content of Precombrian iron-orea as 0.21%; Phanerozolc iron-ores average 1,43% Po^s* Therefore, the Phanerozoic ores particularly indicates that there may be a geochemical link between the two in the marine environment (Altschuler, et al., 1967; Cook, 1972; Laajoki and Saikkonen, 1977; Cook and McElhinny, 1979; Cook, 1979 and Laajoki, 1986). It has been observed by some previous workers that Phosphorus has a strong tendency to be associated with Fe-0^ in many aquatic environment. Bortleson and Fred Lee (1974) have shown that Fe and P are positively correlated in lake sediments and that the oxidation condition controls the rate of Fe in either mobilising or releasing P to the water. Subramanian (1976) has shown that Fe and P are oogenetic in fresh water as well as in estuarine environment and Nriagu (1972) has experimentally verified the role of Fe in P mass transfer in the aquatic environment. In a very highly oxidizing + 3 +5 environment, Fe removes P from water by the formation of sorbed complex on Fe(OH)-, thereby making available only a -3 +2 small amount of PC. for Ca to form apatite in the marine 194 environment (Banerjee and Saigal, 1988). Hence, for the continent derived p to reach the ocean for apatite precipitaion the review should have positive but not extreme oxidising and acidic conditions, any change in these parameters may trap the dissolved PO- 3 in the estua^ine region where the phosphorus could be sorbed by Fe(OH)^ or clay minerals, (see Olsen, 1966; 2+ Kajitani, 1968; and Shangqing, 1984). The ionic radii of Fe Fe and Al are apparently too small to enable thc'.m to + 2 substitute readily for Ca in most natural environment (Cruft, 1972). The Fe^O^ shows a weak and strong negative relationship with Po^c iri primary and secondary phosphorite snmples in the study area. The weak relationship particularly, in primary rocks may be due to non-doposition of Fe^O. content with P-,Oc at the time of phosphatization and on the other hand, the stronger relationship in secondary phosphorites may be due to leading and/mild weathering of iron from the ores and re- precipitation along with P2*^5 ^^ ^^^ Pore spaces, cavities/ voids, veins etc. in highly oxidizing marine environment of the Bijawar basin. The absence of pyrite in these phosphatic rocks of the study area clearly indicated a high oxidizing environment. This relation between to the constituents indirectly indicated the alkaline nature of basinal waters although none of the independent iron-phosphate minerals were detected by XRD O jOi o 1 Q) 195 [cp UL 0) + > .s5 1 ^ c O 0^ -/ LL + O • <3 L: i o / • u % y^ _ j- in tr oc o Q. UJ UJ l/l 0 <3 : 6 1— t— O 1 X < CC tr cc I T" 1 1 I 1 1 o O ^ o m in o in o LU Qo. 0o- a. CO ^n CM a \- tn Ul < ^o , cc o o ^ CD o X X u Q_ o. CL o 0) LL (/) Ui O > o Ui m O C o tr. Ol 0) oo OJ 9- vO x: in h^ c 1 1 ( —T" 10 O Ul O CsJ CM — — o oin LL OS* 196 during the study of all the four types of phosphorites. The higher and negative behaviour of Fe^O^ also indicated the adsorbed state of iron in .these rocks formed under oxidizing marine environment. The minor scale substitution may be possible + 2 +3 in the apatite lattice of Ca by Fe due to close ionic charges (Figure-27). V.3.1 .8. P2O5 vs. FeO : An upwelling environment would serve to explain the large amount of phosphorus associated with iron-ores. Though much more work is required on this topic, the mre-earth patterns in apatite-rich iron-ores support a marine source of the P and by analogy for the iron at the too (Borchert, 1960). During the early Proterozoic, at least, the disposal and concentration of P in marine sediments was supposed to be controlled largely by the distribution of iron and the periodic upwellings of reducing iron-rich ocean voters of the type envisaged by Holland (1973). Like Fe^O^ the FeO shows e\ negative and random correlation with Pp^q i" ^H phosphorite samples in the Hirapur-Mardeora ares. The total iron content may be brought by the upwelling currents to the shallower parts of the basin where phosphati- zation was in progress (Figure-28). 197 V.3.1,9. P^O^ vs. SiO^ The (PO.)" trivalent anions may be replaced by similarly built and equidimensional anions such as divalent (SO,^)" and tetravalent (siO^)"'^ (see Krishnan, 1942; Batekhtin, 1959; Manheim, et al./ 1980; Axelford, et al., 1984). Studies of Husain (1977); Khan (1978) and Viqar (1981) showed that ^^^^ maintained an antipathetic relationship with Si02 in the phos- phatic rocks of Tighora area* district Sagar (M.P.); Pithoragarh area, district Pithoragarh (U.P«) and Birmania area, district Jaisalmer (Rajasthan) respectively. The ionic radii of Si"*" (0,39 A ) and P (0.35 A ) are very close to each other and having a diadochic relationship between both the elements. The 4+ 5+ substitution of small Si ions for P in apatite is well substantiated. If appreciable Si substitutes for P '^, it is apparently necessary to have a corresponding substitution of balance charges. The coupled replacement Si + S • 2P "*" ifii well documented throughout in the literature on the different phosphorites of the world (Heinrich, 1954; Cruft, 1966; Gera- simovskiy, et al.# 1973). Silica show a gradual decrease with + 2 increasing P2^5' while Ca increases simultaneously (Cook, 1972 and Khan^ et al., 1981). According to Banerjee, et al• (1982), the total SiO values has not been considered for any interpretations through the distribution of SiO^ in the phos- rock phatic/of the Hirapur area in Sagar district, : • is controlled by both diagenetic process. 198 A plausible substitution that could help to balance the decrease in charges due to carbonate and sulphate substitution is the substitution of silicate (siO^)" for (PO^)"^. This would increase the negative charges. The silicate substitution in small amounts (Khudolozhkin, et al./ 1972; Altschuler, 1980; Banerjee, et al./ 1980; Manheim and Gulbrandsen, 1983). Exami nation of the phosphorites analyses presented by Bushinsky (1935); Dietz, et al. (1942); Gulbrandsen (1966); Summerhayes (1970) and in this work shows that generally there is an inverse relationship between ^^^2 ^"^ ^2^5 ^^'^^^'^^s- This relationship is primarily explained in term of diluent allo genic minerals such as quartz, calcite, feldspar and glauconite (Parker, 1975). SiO^ shows a progressive negative relationship with PpOc in all four types of phosphorites in the study area. This relationship supported the following informations regarding the genesis of phosphorites :- 1. The (PO,)" has been mutually substituted by (siO.)" before the final precipitation of phosphorites in the basinal environment, 2. The ionic radii and charges of silicon and phosphorus are very close to each other and helped to replacement in the apatite lattices. L"l 6 O 199 in c 6 2 ~ O io 6 > / tn in O / A o or* ( — rsj PO in . i/» + c m 0) .in o o* (7) . O a. . in Ic ctn .o o O in 0/ O 1— o in o op t 1 1— -1 1 —t— O 1 T O in o in O 6 ' LL Q_^ zoo The higher content of SIO in few phosphorite samples may be due to silicification of ores by diagenetic process in the sedimentary basin. The precipitation took place in the marine, shallower conditions of the basin which is a well known fact for all older phosphorites (Figure-29). V.3,1.10. P^O^ vs. MnO : P^Oc and manganese in the phosphatic-stromatolites fro m Jhamarkotra and other areas show antipathetic relationship. Such a relcitionshlp indicates that neither Mn has any direct affinity with phosphates nor it occurs in apatite structure (Banerjee, et al., 1984; Banerjee and Saigal, 1988). The quantitative determination of Mn obtained by emission spectro scopy, also indicates a tendency for the Mn concentration to increase with the decrease in P^^S content. The additional feature evident for Mn is its relatively high concentrations (mean value 2, 445 ppm) in non-pelletal phosphorites of both the cellophane inudstone and phoscrete varieties. The mean values of Mn for pelletal phosphorites is only 479 ppm. The Phosphoria Formation by comparison has an even lower Mn content of only 20 ppm, an indication of its relatively unweathered state (Cook, 1972). The Mn is present dominantly as Mn02ir although a limited amount of Mn substitution in the apatite lattice could EOt conceivably occur in the more manganiferous phosphorites either 2+ 2+ - as Mn , substituting for Ca or alternatively by (MnO-) aubatituting lor (PO^)" (Vauillova, 1958; Cruft, 1966; Rao, et alw 1987). The elements which are located outside the lattice in minerals, either of detrital origin (Si02/ Al20^, K2O, TiO^) or introduced by weathering (Fe203, MgO (?), MnO)• It could be anticipitatjsd that a negative correlation will be apparent between ^n^S' ^^^^^ ^^^ located outside the lattice (Cook, 1972). The distribution of phosphorus in the unconsolidated sediments is mainly controlled by 1) phosphorus content of the mineral source material; 2) the concentration and state of dispersion of MnO and iron compounds in the sediments surfaces; 3) distribution of biogenous matter; and 4) chemical precipita tion or replacement of existing solid phases. The association of P with Mn and iron appeared to result from the fact that the P, Mn and iron-oxides, introduced into the ocean water in dissolved and suspended state are largely deposited together in an oxidi zing environment (Rao, et al., 1987). In the study area, the MnO shows random and weak negative relationship with P2^5 ^^ ^^^ primary and secondary phosphorite samples. This relationship may be due to - 1) non-affinity with ^2^5 and minor occurrences of Mn in the outside of apatite lattices; 2) The MnO may be substituted by CaO in the apatite in lattice on a minor scale. Its contents also present as adsorption on the apatite grains; 3) the MnO may be associated with detrital grains and it may be introduced in the system during weathering process (Figure-30), V.3.1.11. P2O5 vs. MgO : The inhibiting effect of Mg on the crystallization of apatite is evident whether it is in solution or in the original carbonate. These experimental result suggest a pathway for the genesis of apatite and indicated conditions for its formation, which could prevail within the sediment, in very shallow water, during a very early diagenetic stage (Walter and Hanov, 1978; Morse, 1979; Nathan and Lucas, 1981 and Lucas, 1984). Lehr, et al. (1968) have shown that the crystallite sized apatite decreases with the increasing carbonate, sodium and magnesium substitutions. Although the reasons for such relationships are not readily apparent, it seems probable that the concentration effects of Na* Mg and CO3 responsible for the highly substituted apatite structures, may inhibit crystal growth. Banerjee (1978) found that magnesium has a negative correlation with P, as the high P peak is clearly followed by high Mg peak along the traverse in the phosphorites of Jhamarkotra 203 This reflect rhythmic alterations of 'Mg-poor-P-rich* layers with magnesia rich P-poor layers. This periodic rhythmicity of the elements in the laminated phosphatic stromatolites of clearly indicated the affinity of dolomite of the carbonate- fluorapatite during the sedimentation and precipitation in the shallow water basins. According to Khan, et al. (1981), Mg content in phosphorites within thp range of 1 to 2% and MgO has no specific or selective attitude towards ^2*^5' '^^^^ believed that Mg could be precipitated as MgNH^PO^ under highly alkaline conditions and in the presence of chloride ions. But the pH of the precipitating system might have not been so favourable and further the insignificant amount of chloride ,ions restricted such precipitation. Like MnO, the MgO is also having a random and weak negative relationship with Pn^S Pa^^^icularly in primary phos phorites and slightly positive in the secondary phosphorite samples of the study area. The difference in geochemical behaviours of these two oxides may be due to - 1) ionic substitution of Ca in the apatite crystal lattice during highly oxidizing, alkaline environment of the basin; 2) pre cipitation in the marine and shallower parts of the basin; 3) the substitution of Mg by Ca in the apatite may decrease the crystallite size of the apatite by the increase in size of Mg ions and 4) the minor amounts of MnO in these phosphorites .o csi zo^ O a- P / / 6 ^ / .Q> tf\ 6 o o H- QT 6 / + v^ c / 0 ^ cu 4- O • < o cu • / < ip o" J o • -^ h- jd"a J < r ^ -4- 6 a. I (^ sz Q: I 6 in oi c UJ UJ o I 1 o CL 6 o j5 Q: o ,x ~~* CD LxJ o CL I / CL 6 ^- Q- CM** (/) cr o _, , J ~1~ o CO o O X m o L/i O 7 OL X Q. < -J (O Q_ u if) UJ 6 > 10 LL o Q: X O CL < U Q —I o u o < < UJ (/) in o O) ^ (N n CN 2 A 9 (n •^ > / in v^ / O ~" CL^ / , -T "^ ^ c / CN o CD 0) / O ^ «^ o Ol Q) :E J3 ^ o / IE \ + vp in / 6 c o ^ •^ N) / •^ \ + 6 J2 / oJ 0) °-> + 6 ~ I r^ —r~ O i/i o ^ O o in 10 ^ -T (^ LL in QT 205 with random behaviour in primary phosphorites may be due to poor supply of Mg from source rocks, restricted circulation of basinal waters (Figure-31), V.3.1.12. P20^ vs. Ti02 Goldschmidt (1954) reports that under some conditions TiO^ is absorbed by clay minerals. The antipathetic relationship shown by 'detrital trace elements' is an inverse correlation with ^2*^5 content. Such a relationship is clearly exhibited by TiO^, which is located predominately in detrital rutile, ilmenite, leucoxene (Cook, 1972). According to Cook (1972), the TiO^ data marked a trend of increasing TiO with decreasing PjOc is quite apparent in all types of phosphorites. The TiO content of thr* non-pell etnl pho.^phorJ to ia, howovor, hirjhor than that of the pelletal phosphorites. This primarily results from the presence of abundant fine detrital grains in the cellophane mudstones. The TiO^ content of the phoscretes is low due to the titaniferous minerals remaining relatively insoluble during the solution,mobilization and re^precipitation of apatite as phoscrete. Like, MnO nnd MgO, the TiO also shows a weak and linear negative relationship with P^^c in all phosphorite types in the study area- This relationship indicated the location of minor 206 + O • <3 Ui tr o t UJ UJ X Q. tr (/) O o O UJ X X X QL a. a Q: U) en o O o X X X o CL Q. o in a o > UJ X UJ Q_ a: CQ < Q UJ en M < o o ^ X UJ ? o •-^ fM ro '^ GO in O c ^ •«-* o JS 01 o Q: fO O 1 a> c3 IZ 207 amount of TiO^ outside of the crystal lattice of apatite by mutual ionic substitution end/adsorption on the mineral surface of apatite, in addition to iron aPd clay minerals and the presence of a few detrital grains of rutile and ilmenite. The random correlation of Ti02 with P^O^ may be possible due to leaching/mild weathering, remobilization and reprecipitation as shown in the petrographic study (Figure-32). V,3.2. Inter-relationships between various Oxides : V.3.2,1. CaO vs. CO2 J The mobile elements are defined as those most commonly available from solution, they incJlude the elements like calcium, magnesium, manganese and strontium, one or more of which charac terize the carbonate fraction of most black shale deposits. These elements are commonly precipitated directly from sea water (Vine and Tourtelot* 1976). In the study area, the CaO and CO^ show strongly positive relationship in all types of phosphorite samples. This progressive positive relationship of the two constituents further support the chemical composition of carbonate-fluorapatite ^^^B^^^O^) 2 CO^F) and direct precipitation from sea-basin conditions of the sedimentary Proterozoic basin (Figure-33). 208 V. 3.2.2. CaO vs. H2O'*' Water is one of the volatiles released when the apatite is heated. This water is probably as present in the crystal as 2+ 3— hydrogen ions (H^O^) substituting for Ca and (PO^) " (Simpson, 1964). In the study area, in the primary phosphatic-shale samples they show weak positive correlation but in the samples of secon dary phosphorites associated with ironstones and quartz-breccia phosphorites they show weak negative relationship. The weak positive relationship in the shale-phosphorites may be due to non-weathering process in these samples and the negative relation ship in the secondary phosphorites may be due to ionic substitu tion of Ca"**^ by H^O^ {Figure-.34) . V.3.2.3. CaO vs. Si02 2 The increasing CO2 pressure in the waters leads to the deposition of CaCO^ during diagenesis while Si02 being gradually removed with the increase in pH (Degenes, 1965; Krauskopf, 1967; Awasthy, 1970 and Verma, 1975 and Khan, 1978). Fairly complete substitution for calcium has been demonstrated for Si, Ba and Pb for the halides and for hydrophosphates (Kreidier and Hummel, 1970). In the study area, in all the four types of phosphorite samples show strong negative correlation between CaO and SiO^- E09 o K* o in O o C o >*• in + o > m \ rr> o o a \ o o o \ c + O • <] \ in O \ "^ C \ ""I LU \ o '^ Q: o \ \ Xo in LU lU Q. + \ O t/) < t: '\ o cr O \ c o o X \ o o I— X. X Q- Q- Q. in \ o JS o o a* < o X o a; X. X O \ CL CL Q- (O o 1 r r r T u O lA -I r o «n o >- in ^ o lA O X UJ •si ro a. 2Z m cc O H- N < 1— O Ui o a: < 21 o < a L X o o a <3 u 1—0 t/C>M rn zio + 2 +3 It may be due to substitution of Ca by Si during the high pH conditions of the Bijawar bas4,n waters (Pigure-35). V.3.2.4. CaO vs. MnO Calcium may be replaced in part by Mn, Cr, Sr, Or in small parts by Na, K, Mg, Fe, or even carbon (Winchell and + 2 Winchell, 1968) . Isomorphic substitution of Ca cations by Mn ions and V **" (VO^) *^ were observed in the ancient phos phorites (Krishnan, 1942; Heinrich, 1954; Cruft, 1966; Khudolozhkin, et al., 1972; Gillnskaya, et al./ 1984 and Pettijohn, 1984), In the study area, CaO and MnO show progressive positive relationship in the shale phosphorites but on the other hand, the other phosphorite samples do not show any clear-cut relationship. This relationship may be due to ionic substitution of Ca 2+ by Mn2-jr and further addition or adsorption of MnO in the apatite crystal lattice during and/after the formation of phos phorites (Figure-36). V.3.2.5. CaO vs. Fe^O^ The most variable element is Fe^O^ and this correlated with variations in the concentration of goethite found in thin sections as well as by XRD analysis. One sample gave an abnormal value of 50,16i% Fe^O^. In comparison to this sample,other samples o 211 oO LL U3 a o o c 2 CD + o LL o UJ a> o Q: oX tn UJ UJ Q. o ^ cn c on o UJ o X o o X CL X Q- QJ tn S cn < Xo oX oX O OO OL 0. Ou o in UJ o >- (X aX. a: UJ m O < z a L Q Vo— M o UJ tn _i 2o tr o < O O < X u Q: 3 o in U) a Uoo — r*4 f** u> o c o C^ ^o c r*} U2 O cu LL K CO hu> tn h^ c o h fv» cu cr O lO O O 8 11 in have a much lower ^^o^S ^^lue. The F^n^S content is high in ironstone phosphorite samples but the other phosphorite type samples are also having Fe^O^ concentrations. These Fe20- content may be due to occurrences of ferruginous minerals like hematite, magnetite, limonite and goethitic coatings. Both CaO and Fe^O^ show strongly negative correlation in all the phos phorite samples. This relationship may be due to mutual ionic + 2 substitution of divalent cations of Ca by trivalent cations of Pe"^^ (Figure-37) . V.3.2.6. CaO vs. FeO : In the study area, the divalent iron (Fe ) also shows similar relationship with CaO as like trivalent iron (Fe*** ) in all the samples of phosphorites. This may be possible due + 2 to mutual ionic substitution of Ca in the similar environmental conditions of the basin (Figure-38). V.3.2.7. CaO v&. Na20 : (1966) Simpson^ from an experimental study concluded that the formation of calc-phosphate could be enhanced by the presence of sodium ions in the solution and calcium ions in excess of those of magnesium. Banerjee, et al. (1983) stated that between 213 these two elements which indicate negative correlation, only a small part of ^32^ l^as been substituted in the apatite structure, while the rest of it occurs in other minerals. Further, Banerjee, et al. (1982) suggested that the random distribution pattern, between the two constituents reflects varying degrees of weathering at different locations^ Smirnov, et a!. (1962), and Russell and Trueman (1971) suggested that Na and SO^ contents of phosphorites from Queensland, Australia* indicate forma- tional environments of high salinity* In contrast to above, Cook (1972) suggested that chemical variations between the phosphorites of Queensland might be due to sub-aerial weathering and that such a process that was operative during formation of phosphorite were responsible for the observed chemical variations among the Queensland phosphorites. Gulbrandsen (1960 and 1966) has shown that there is an approximately 1 : 1 relationship between the atomic ratio of S to Na in the Phosphoria phosphorites and he has interpreted this as reflecting a coupled substitutions in the phosphate mineral of Na"^ and s"^ for Ca"^ and P"*" . According to McConnell (1938), Krishnan (1942), Altschuler, et al. (1952), Parker (1975) and Altschuler (1980), apart from trace amounts of pyrite and feldspar, there are no S or Na minerals in the Agulhas phos phorite and it is therefore suggested that the S and Na values determined for these rocks reflect substitution effects in the francolite. + 0 • < u cr Ui o b: (n o a: Xo 111 CL o Q-. in QL o tn cE X o < O a. X CJ Q. Q. t_) l/> >- LU O Q: UJ QX- < z; Q o LU 2 1— N O Q: < o o < X a: m utn !-• C5 ^ fSI p^ 215 The Ca may be replaced by Sr, Ba, Mg, Pb, REE, Na, Mn and Fe+ 2 media of various compositions (Winchell and Winchell, 1968; McClellan and Lehr, 1969; Khudolozhkin, et al., 1972 and Pettijohn, 1984) . In the study area, ^Qo*^ shows random and neqative correlation with CaO in all phosphorite types. The presence of Na2*^ in these phosphorites indicated rapid phosphatization and small scale substitutions in the apatite lattices. The random relationship in a few of the samples may be due to sub-aerial mild weathering/leaching of the ores. This relationship indicated higher palaeosalinity of the basinal-sea waters during the time of phosphatization. This relationship also supported the muturil ionic substitution of Ca+ 2 by Na+ 1 in the carbonate fluorapatite phase (Figure-39), V.3,2.8, CaO vs. K2O Like Na^O, the K2O also shows the same random and negative correlation with CaO in all types of phosphorite in the study area. Thus, all the aforementioned observations of CaO vs. Na20 may be application to CaO vs. K^O.(Figure-40). E16 V.3.2.9. CaO vs. AI2O3 : According to Banerjee, et al. (1982), crandallite, an aluminous phosphate of Hirapur area seems to have formed by variable substitution in the apatite structure along the apatite ^ crandallite > millisite weathering series. The lower half of the working face of the Lamlam quarry of phosphorites of Theis/ shows how sediments consisting of alternating apatites, montmorillonite-illite and chert are changing to bedded, kaolinite and goethite rich, aluminium phosphates (Flicoteaux, et al. 1977). From bottom to top, following evolutionary succession of phosphates appears :- Fluorcarbonate - apatite > millisite Ca + crandallite Sr ^ crandallite Ca (wavellite). This evolution leads to minerals which are increasingly depleted in Na, K, Mg, Sr, Ba and also in P, it is accompanied by i) decarbonation of the carbonate-fluorapatite; (ii) disso lution of silica minerals, chert and detrital quartz, (iii) neoformation of kaolinite, first in situ by weathering of sedimentary clays, then by migration and precipitation in secondary cavities in the form of zoned coatings; (iv) indi vidualization of goethite formed by the iron removed from sedimentary clays; this goethite is either adsorbed on the kaolinites or concentrated in micro-nodules (Lucas, et al*, 1978). o 217 00 O LO ^ c3 C (U cu + O • <3 Q. LU "x: c cr o o US Q_ (/> t or - I " ir o O 1 T i 1 Q: o X o in O LO O) UJ CL (/) t/> -sT vT ro en fN ^ CM ^ in o o o X X o o CL DL o o t/> LU O O X m CL < o Q N Ul Z (/I —I o tr < u o < u 3 ^ en o i/> o) *-• a CM < _ 00 — rs» CO o O / / <* - to 5 cT < - in C < 01 - -^ 01 - ro /<3 - CM 0 en /o c o / ^ O 1 1 1 T 1 1 1 1 1 01 m cD o m o ^ O tr» o m o tn -4^ vT ro p,^ r«4 rsi ^ «• O (5 218 In the study area, CaO has a negative correlation with phosphorites. AljOo in the primary as well as secondary^ This relationship + 2 +3 may be due to ionic substitution of Ca by Al in the carbonate- fluorapatite phase due to weathering of the ores. This relation ship confirmed the formation of secondary apatite phase as crandallite in which the apatite > crandallite —v millisite series on one hand and on the other clay mineral > montmorrillonite ^ kaolinite assemblages were confirmed by XRD study. The presence of crandallite indicates that + 2 +3 substitution of Ca by Al in the apatite lattice was not complete because no wavellite was detected by XRD study. However, the mineralogical assemblages which is associated with phospho rites may be due to i) mild decarbonation at the primary apatite phase; ii) precipitation of secondary silica for compaction of the ores; iii) formation of iron and clay benring minerals, minor migration and reprecipitation in secondary cavities fillings in the form of goethite coatingo/ etc, (Figure-41). V.3.2.10. CaO vs. MgO : Cruft, et al. (1965) and McConnell (1973) reported that + 2 4-2 since Mg could be substituted for Ca in the apatite structure, it is quite possible that both CaO and MgO were competing during diagenesis for their survival in the presence of PoOn. During 219 phosphatization, it was observed that a chain of replacement among CaO-MgO-P^Oc was in during phoophotization and is noticed that MgO acted as a catalyst in the process of replacement of CaO by P2*^5 ^^^^ Bachra, et al. / 1965; Gulbrandsen, 1969; Martens and Harriss/ 1970; Atlas, 1975 and Burnett, 1977). Amorphous calc-phosphate can rapidly convert itself to apatite in Mg-free sea-water by exchanging Mg + 2 for Ca +2 ions from the water (Krishnan, 1942; Martens and Harriss, 19 70; Banerjee, et al., 1980). According to McClellan and Lehr, 1969; Manheim and Gulbrandsen, 1983; PettiJohn, 1984; Simpson, 1966), magnesium appears to substitute in small amount for calcium in most marine apatite. Because Mg is much smaller in cell dimension than that of Ca, its substitution in large amounts +2 + 2 is not favoured. Mg is divalent like Ca and therefore, impose no change in the balance of changes; it is included as a component of apatite in formula, Cag ^Mg ^ ^^ 4^^^4^5 1 (SO^)^! (003)^3 (C03F)_5 F^. Direct precipitation of apatite in sea water upon addition of dissolved inorganic phosphate is inhibited by Mg-ions. In sea water amorphous calc-phosphate precipitates rapidly converts itself to apatite in Mg"^ free sea water through exchanging for Ca"*"^ (Heinrich, 1954; Winchell and Winchell, 1968; Martensand Harris, 1970). o 8 220 1^ (A f fN*. > ^ fNl 9. Li. fSJ cy ^ f O IVl 0) o ^ - *^ ^^ o X Ui Q. c lu ;J; cn o a: Q: o o UJ o X h- X X IT Q. Q- O tn in X o U CL X o O in Cl. X o OL u X >• CD CL cc u < O U I- M -J < S < 33 i8D in en rNj — (Ni ro o a; 221 Like Al and alkalies/ Ca can be replaced by Mg in the apatite crystal lattices under the shallower marine conditions. The negative correlation between CaO and MgO in the phosphorites of the study area,in lias with the above observations. This chemical reactions supported the diagenetic formations of phosphorites. This relationship also supports the direct inorganic precipitation of primary phosphorites. The pH and Eh of the basinal water of Bijawar basin may be neutral to slightly acidic in nature during diagenesis process (Figure-42). V.3.2.H. ^6203 vs. H20'^ The trivalent iron (Fe ) and H«0 show progressive positive relationship in all the phosphorite samples of the study area. The water played a very significant role in weathering, erosion and redeposition of phosphorites of this area- During the process of formations of phosphorites iron- oxides also migrated from the host rocks of the Bijawar Group and deposited' along with water and P^^-'s content (Figure-43). V.3.2.12. Fe^Q-j vs. CO2 : In the phosphorite rocks of the Bijawar Group of the study area/ known as Gangau Ferruginous Formation, iron was 222 present in appreciable quantities at the time of deposition of phosphorites but the absence of any iron-phosphate mineral may be due to the occurrence of carbonate-fluorapatite phase (cellophane and dahllite) in the phosphorite rocks. The above facts are supported by the progressive positive relationship between Fe^O^ and CO^ in all the phosphorite samples (Figure-44) V.3,2.13, Fe^O^ vs. AI2O2 s The results obtained indicate that during weathering there is an overall/ though somewhat irregular, increase in most major eleirents located outside the apatite lattice (si02# AljOo, Fe^O^/ K2O (7), MnO, H^O). Their increase in concentra tion in some instances may result from the insoluble nature of the host constituents though in general/ is probably the result of introduction of the elements during the course of weathering (Cook, 1972). In the study area, the ^62*^3 ^"^ ^^2^3 ^^^^ strong negative correlation with each other in all the phosphorites. This relationship may be due to mutual ionic substitution of Fe"*" by Al in the similar physico-chemical conditions of the basin. This relationship is further supported by the presence of AI2O3 outside the crystal lattices of cellophane in the primary phosphorites and formation of crandallite in the E23 o O w ^^ > cn QP o 00 o u. c o o^ CD ^ o o ^ in h^ J:^ o CL + o • ^- fM ro -^ 224 secondary phosphorite samples. It appears that Fe^O^ and Al^O played an important role in course of formation of primary and secondary phosphorites (Figure-45); V.3.2.14. Fe203 vs. TiO^ J The elements like Al-K-Ti-2r consistently group as clays and that with leaching of these phosphorites, Ba, Th, Ce, Ni and Sr substitutes for elements in the clay structure or are adsorbed on to clay surfaces (Cook^ 1972 and Howard and Hough, 1979)• The phosphorites of the Hirapur-Mardeora area showing weak negative correlation between Fe^O^ and TiO^• This weak relationship of these two constituents may be due to non availability of Ti02 content in the basin or poor mutual ionic + 3 +3 substitution of Fe by Ti at the time of formation of phos phorites. It may also be possible that a minor quantity of TiO^ might have arrested in the ferruginous and phosphatic gels and clay bearing minerals (Figure-46)• V.3.2.15. Fe^O^- vs, FeO ; The oxidizing to reducing conditions are favourable for phosphorite precipitation and it also favours the increase of ferrous ions in some of the phosphate minerals (Betekhtin, 1959) 225 + o • LLI tl Q: o u t: t: o or: o cr X u 0- O CL ti OL cc tn ton — •— rsj CO 226 Wedepohl (1970) noted that iron during weathering is converted into ferric-oxide and carried as stabilized coliolds or as adsorbed coatings on detrital particles. The iron content which is adsorbed on these colloidal particles is separated according to their settling velocities. It is believed that iron depleted reduced palaeosols are common in early Precambrian rocks. Hence, existence of weakly oxidized early Precambrian palaeosols suggest that early Precambrian (Archean) atmosphere did contain some free oxygen (Banerjee, 1985). The phosphorite samples of the study area are having very high concentration of Fe^O^ and low content of FeO in almost all the samples. The presence of high to low contf>nt of trivalent (Fe"*"' ) and divalent (Fe ) iron indicate very high oxidizing and poor reducing conditions of the sedimentary basin at the time of deposition of these phosphorites. The high content of Fe«0^ might be present in a colloidal state. The occurrences of hematite, magnetite^ goethite, limonite, etc. and absence of pyrite further support high oxidizing condition of the basinal + 3 +2 sea water. The dominating phase of Fe over Fe within the palaeosol indicated that the formation of phosphorite took place probably early to middle Precambrian age. However, the negative correlation between ^^o*^"^ ^"*^ ^^^ "^^ these phosphorites clearly supported the above cited evidence regarding their formation (Figure-47). 227 V.3.2.16. ^€20^ vs. MnO : MnO is distinctly enriched in these iron rich rocks as compared to the iron poor rocks and this is possible linked to the 'Scavenger' activity of the ferric-oxide, such as goethite. However, the individual analysis shows that the lower MnO value is associated with the samples containing the highest Fe^O^ value (Parker and Sieser, 1972). Strong affinity of Mn for Fe is well documented in geological records. Hence, higher concentrations of Mn in ferruginous phosphorites of Hirapur appears to be a normal genetic association, AS borne out by the analytical data# Mn shows positive correlation only with Pe , which further confirms Mn-Fe association (see Banerjee, et al./ 1984 and Saigal and Banerjee, 1987). It is therefore, logical to believe that both Mn and Fe introduced into the phosphorites by weathering remain located outside the apatite lattice - an absorption supported by the studies of Cook (1972). The Mn and iron-oxides precipi tate phosphate from sea water in contact with sediment surface (Rao, et al.. 1987). Murty, et al. (1973 and 1980); Rao, et al., (1976) have clearly established the presence of non-lithogenous iron and Mn in the form of hydroxides in the shelf sediments, particularly in higher concentration in the shelf region. In view of this fact, and its negative correlation with Mn in the 228 c CD 2 IT) U) > Q r> ^o o ' o s^ 0) + O • <] •lA o O c c a; (NJ 2 CD cc in CD o T ^ O U) Q_ UJ 01 ^ Q. (T cr CL o J: Ui 2 o ^-* t/> 0(/-) < cc O o •^ d o o X X O CL a. Q. u o to LU 5 o >- cr X cc U m a: Q, < o N Q lU 2 v- -J O 2 cr O < o o < X LU Q: =D 12 cp Li- if) (/) »-» (3 rsi CD rsi CO ^— O Up cn •~ :E ^J jn — o > rsi ^ o ' o i2! c^ en ^~ 2 C op a; d 4-» up 0) d j:i ^ a. d JZ (N (A O c o a: (3 Li. 11. 229 shelf region. In view of this fact, and its negative correlation with Mn in the northern region and the lack of any correlation in the south, it seems possible that a part of phsophate in these sediments was fixed in association with iron (as ferric phosphate?) In the study area, the ^®2^3 ^"^ ^^^ show progressive positive relationship in the phosphorite samples. This type of behaviour in these two constituents may be due to oxidation + 3 +2 followed by mutual ionic substitution of Fe by Mn and adsorption of MnO in the crystal lattices of apatitic minerals, captured by high iron content (goethite, etc.) and weathering of the ore in the later stages (Figure-46)» V.3.2.17. FeO vs. MgO : The antipathetic relationship has been obtained in the phosphatic rock samples of Pithoragarh area (U.P.), India/ which + 2 +2 has been postulated due to the similarity of Mg with Fe ions that caused mutual substitution of each other under similar physico-chemical conditions for their enrichment (Khan, 19 78). In the study area/ the divalent iron (Fe ) is showing negative correlation with divalent magnesium (Mg+ 2) in all the samples of phosphorites. This type of relationship between these two elements may be due to mutual ionic substitution of Fe by + 2 Mg in the similar physico-chemical conditions of the Bijawar basin (Figare-49). o" E30 o c + o 0) u tr cc UJ o (n UJ CL c o cr cc o o X LU o a. CL H- 0(/ ) (f) 01 cr o o X o a: a. IX X if) 0- u o LU T > cr n. IX. < o GD LL UJ yn in -J n N < t) o cr X 111 G: en t/) i-i < o ID GJ *- (N n vj- :«! 01 c Oi 01 0) c o 01 Q: to o iS Ll. 23t V.3.2.18. Feo vs. MnO : The manganese mineralB have clooe pornlloliom to tho iron minerals due to substitution of Fe+ 2 by Mn +2' under ordinary conditions (Eriksson, et al.# 1975). The progressive positive + 2 +2 relationship is also seen in between divalent Fe and Mn as like trivalent Fe and Mn in all the phosphorite samples. + 2 +2 This relationship between Fe and Mn may be due to mutual ionic substitution (Figure-50) V.3.2.19. FeO vs. Ti02 t Israili (1978) believed that besides AI2O3 like Fe203, FeO, MnO and Ti02 also gradually increases with the enrichment of P2^5* This is due to the fact that all these oxides require almost similar sets of physico-chemical conditions. The divalent iron (Fe ) and trivalent (Ti ) oxides show progressive positive relationship in the phosphorites of the studied area. This type of relationship in these elements may be due to mutual ionic substitution during the diagenesis of phosphorite sediments and during which both the elements might have been accommodated in the crystal lattices of apatite (Figure-51). 32 V.3.2.20. AI2O3 vs. TiO^ t The major elements like Al202/Ti02/ ^0*^5' ^^^' ^^^ ^"^ to some extent MnO are thought to be less mobile. They have been liberally used in discriminant diagrams at least quantitatively by many authors (Pearce^ et al., 1977; Mullen, 1983; Coish, et al», 1985 and 1986) to discuss the petrogenesis and tectonic setting of both altered and unaltered volcanics. ^12^^ and TiO show progressive negative correlation between them in all types of phosphorite (altered and unaltered) samples. This relationship may be due to mutual ionic substitution of trivalent ions of Al by Ti in the shallower conditions of the sedimentary basin. They niLght have been adsorptive on the surface of the apatite crystal lattice in the unaltered phosphorites the phenomenon is supported by the presence of aluminous-phosphate (crandallite) in the altered phosphorite samples (Figure-52). V.3.2.21. Si02 vs. AI2O3 ' Israili (1978) reported a progressive increase in Al 0-. indicating the precipitation of phosphate under controlled physico-chemical conditions (Eh, 0.4 - 0,6 and pH, 7.1 - 7.8). The high Si02/Al203 ratios could be explained by a loss of aluminium which has a higher solubility than silica in a very acidic conditions (Krasukopf, 1956; Wey and Siffert, 1961). (N 233 o \ \ 00 c5 ^ frM o o 4 O • <] up (7> \ o ^ o m rsi 0c1 o o CD UJ ^:A,i o CD cro UJ LU CL \ \ o V- tz o tr cr X fsi (n w o o a. O c a. \\ o r^ tn QtLn o < 5o X oX o w o J2 a. CL Q- o in UJ r "T" —\ r A —r o o cr o O —r o m vn > U m CO XTi O Q- Q: CD in ^j" la < z o ho- N rM UJ 2 in V- CD —I O 2 cr o < u O < I UJ Q: :D (7) en (/) ^-• C5 (^ n -^ 234 The unaltered phosphorites (shales, ironstones and quartz-breccia) samples show a strong positive correlation between Si02 and Al^O^ but in the altered phosphorite (secondary) they do not show any positive relationship. In unaltered phos phorites, the positive correlation and higher contents of silica and alumina may be due to the abundance of quartz, chert, silica cements and feldspars and cryptocrystalline clay minerals. On the other hand, the weak positive relationship and poor contents of silica phosphorites may be due to weathering and leaching. The high and low content of iron might have also played an important rolo In the relationship of thesn two constituent.c in the sea-basin of the study area (Figure-53). V.3.2.22. SiO^ vs. TiO^ : SiO^ behaves more or less similarly with TiO as that of AljO, with Al20^ in the altered and unaltered phosphorite samples. In unaltered phosphorites, SiO^ has positive relation ship with Tio but in altered it shows a weak or no clear relationship (Figure-54), V.3.2.23. SiO^ vs. Na20 Soda in the phosphorites of the area studied is positively correlated with silica. It suggests its presence + c • <1 UJ or !rl LU CoL y- W- If) cr tr o UJ o o aX. J— ^ rM ro ^ o-fN (/) C rsl Q; cu JC en c o "QI Q: to o LL if) 236 in thG clastic, whereas isomorphic substitutions are more intense especially in the phosphorus site (Al-B.:3ssam, et al., 1983). The negative correlation between SiO and NajO with phosphorites of the study area may be due to +4 +5 isomorjihic substitution of Si by P and fixation of sodium ions in the phosphorus crystal lattice during these processes (Figure-55). V.3.2.24. Si02 vs. K2O : Local variations of these two SiO^ and K2O major elements illustrated an inverse relationship on the one hand and Po^s ^^^ ^^^ ^^ ^^^ other. These variations are linked to variations in the concentrations of diluent quartz and glauconite grains (Parker, 1975). SiO shows a strong negative correlation with K2O also as like that with Na^O in all types of phosphorites in the study area. This relationship may be due to much localized as well as rock types variations in the sedimentary basin (Figure-56). V.3.2.25. SiO^ vs. P^^O^ : The model for SiO^ distribution laterally and vertically may be interpreted as micro-basins of sedimentation for the iron-ores and phyllites along with silica content. The non- ^37 > fS O in c 0) 4- O O UJ D: o UJ LU a. c en o a: o o o X UJ Q- (/) cc- tf)o o Q: U O X X In a. tL CL O if) LU o LU or X cr m Li. a. < M LL) Q if) -J or < O o < X o UJ I/) to «— fN ro r o en c a> a; a; -O O- '-C V) c o Q: in homogeneity of Lateral and vertical section for the multi variate forecasting may be due to the secondary enrichment of Fe202 or due to leaching of SiO^ along the vertical direction (see Raikar, 1987). In the study area, SiO^ and ^^2^3 show strongly negative correlation in the samples of unaltered phosphorites but they do not have any clear relationship in the samples of altered ones This relatloni^hip may be duo to minor scnlf? Ir'.iching of SIO both laterally and vertically from the phosphorite by circul.-^ting ground water and enrichment of secondary Fe^O^ in the form of goethite, limonite, iron-oxide coatings etc. on the surfaces of the phosphorite (Figure-57). V.3.2.26. Si02 vs. FeO : In the unaltered and altered phosphorite samples SiO« shows negative relationship with FeO as it is with ^620^. This relationship further supported all the evidences regarding the Si02 and ^^2^3 relationship and secondly the minor content of FeO in these samples may be occur with the association of clay minerals, other detrital materials and iron bearing minerals also (Figure-58). 4 O • UJ or o UJ u tQoL •-" >— o cc a: X LU a o Q. V^ a. Q_ or in o < o oX X u d. OL a. u U) UJ o tr X >- UJ m DL < Q Ho- N LU 2 t/) t- —1 O Z Q:: < U o < X UJ cr :3 tn tn 1—• c$ — IN ro E40 V.3.2,27. Na20 vs. K2O 1 Relative to seo water, the interstitinl wnter ot thf -2 +2 'basin' sediments show large depletion in SO. ' and Ca accom panied by large enrichments in alkalinity, NH^ and phosphate (see Shok, 1973). Sodium and potassium are sympathetic elements and because they can easily co-exist having the same number of valency and ionic charge (see Hussain, 1977). The low concentra tions of Na^O unlike KjO supports a low temperature to humid climatic condition at the time of precipitation of phosphatic rocks (see Khan, 1978 and Viqar, 1981). Both the alkalies (Na20 and K^O) show a strong positive correlation in all the samples of phosphatic rocks in the study area. These two elen>ents can be easily accommodated in the apatite crystal lattice due to sympathetic and monovalent nature. Therefore, sympathetic relationship of both the consti tuents reflects a temperatOe to humid climatic conditions of the Bijawar basin at the time of phosphate precipitation (Figure-59). V.3.2.2B. l^a^O vs. AI2O3 The soda behaves strongly negative with alumina in all types of phosphorite samples in the study area. It can b. 241 possible that most of the soda contents from the phosphorite ores have been leached out by minor activity of weathering leading to the enrichment of alumina because soda is more mobile than alumina (Figure-60). V.3.2.29. Na20 vs. CO2 Comparing the CO2 content with the NajO content marked separation of the pelletal and non-pelletal fields is achieved, but in this case both show a positive correlation (Cook, 1972), The reason for this apparent Na20-CO2 correlation is somewhat puzzling as Gulbrandsen (1966) has demonstrated that Na is involved in a coupled substitution of Na for Ca and P respectively. The only conceivable coupled substitution involving Na20 and CO2 is of Na**" for Ca and CO3 for PO^", thus preserving the charge valence. Such a substitution would, however, be contrary to a considerable body of evidence (see Smith and Lehr, 1966) that CO^ substitutes in PO^ as CO^F. In addition such a substitution would require a 1 : 1 C s Na atomic ratio, whereas, the C 5 Na ratio of the correlation lines is approximately 2 : 1 for the pelletal and 5 : 1 for the non-pelletal phosphorites. The apparent Na2*^-C0« correlation may in fact, merely be a second order correlation. However, at 1+ ?+ this stage the possibility of a limited amount of Na for Ca and CO^ for (PO^) " coupled substitution in the Queensland o n J ii ro 242 > O + o # - U Q- a: 2 < O Q 1— N UJ 2 (n h— —I o z cr < U o < X UI cr 13 tn tn 1—1 C5 ^ rsi ro vj 243 phosphorites, Australia, cannot be completely rejected (Gulbrandeen, 1970 and Cook, 1972). In the study area, Na20 and CQ^ show progressive positive relationship in almost all types of the phosphorite samples. This type of relationship may be due to coupled substitution of Na"*" by Ca"*"*^ and CO^" by PO?" in the apatite crystal lattices tidal to intertidal cycles in which the variability of pH of the basinal waters (more alkaline to low alkaline) and formation of phosphorites due to metamorphism, alteration, weathering, transportation and redeposition in the same basin (Figure-61). V.3.2.30. Na20 vs. H20'*" Besides carbonation, ancient phosphorite have a reduced content of sodium and molecular water (Gilinskaya, et al., 1984). 1. As for the water in the moleculaJ^ form (H2O ) in carbonate- apatite was established by the nuclear magnetic resonance spectroscopy (Vakhrameer and Zamin, 1979). The ancient phos phorites containing small amounts of carbonate-apatite as characterised by a small content of molecular water. In the phosphorite samples of Hirapur-Mardeora area, ^^0^ shows a a. progressive positive correlation with H2O as like that of CO^• This relationship supported the presence of some molecules of water (H2O'*') within the crystal lattice of apatite (Figure-62). o ^ .(N ro h^ o- c + O • <1 iS: LU or o JZ in u UJ (/) c H- »— o Xo 5 or LU CoL CoL JS w- 01 t/1 < CC o — a: Xo X u o Q- CL u <5' LU o >- CD a: LL X < o M a (n UJ o z: o: < u o < X IJJ cr 3 in u> v-« O n (N •^ fN ro vT fN nj m c o OJ (A C o t 1 1 1 1 1 1 I 1 ' o to rs 00 o ro •« u. 245 V.3.2.31. Na20 vs. ^e^O^ According to Bremner (1975 and 1978) pelletal phosphorite have lower iron content and higher Na«0 values than glauconised pelletal phosphorites. The glauconitized pelletal phosphorites differ from pelletal phosphorites mainly in their high iron content. Both the pelletal types have the same aerial distri bution pattern which Led hitu to conclude that the chemical conditions of the environment must have fluctuated. The glauconitized pelletal phosphorites also have lower sodium values. l*oth these factors suggest that the environmental influence was related to periodic influx of iron-rich river waters which would have favoured formation of glauconitized pelletal phosphorite types (Fuller, 1979). In the study area, the ^^2^ shows a strong positive relationship with Fe^O^ in all types of phosphorite samples. The iron as well as sodium content is relatively high in the phosphorites. This indicated that the chemical conditions of the sea-water basin fluctuated at the time of precipitation of primary and alteration and redeposition of secondary phos-r phorites in the Bijawar basin. It is apparent that basin water must have a highly oxidizing conditions (Figure-63). E46 o fM + o c a; UJ t (U a: o 0) CL LU LxJ o cr Q: X UJ o o a. a. Q. c Q: ifi o o o o ^ QL X X U J9 if) Q_ Q. U o UJ X >- m a: a: u ^ >«^ < UJ Q o 21 I- N 6 -J O < o < (N X u »-• CD CO tun ^ r^ m vr CD fM 247 V.3.2.32. Na20 vs. FeO : The Na^O also behaves similarly with ferrous-oxide (FeO) as like that with Fe^O^ in all types of phosphorites in the study area- But the FeO content is poorer and/lower in amount in almost all the phosphorite samples as compared to Fe^O^ content. The poor content of FeO in these phosphorites indicated a slightly reducing environment for a short duration between high oxidizing conditions of the sedimentary basin (Figure-64). V.3.2.33. K2O vs. Fe^O^ The high K2O values in the samples have been attributed to the presence of feldspar and glauconite and the enrichment in Fe^O^ is also correlated with glauconite as well as goethite (Parker and Slesser, 1972). in the study area, K2O and Fe^O show a strongly negative correlation in all phosphorites. Such a relationship between these constituents may be due to different mineralogical composition of the phosphorites- The K^O content may be due to presence of some feldspars, muscovite, sericite, clay minerals, etc. and Fe^O. may be due to presence of pre dominating iron bearing minerals like hematite, magnetitic, goethite, limonite, etc. (Figure-65). 248 V.3.2.34. K2O vs. FeO s The potassium and iron enrichment found in the Agulhas Bank, N.W. African rocks is due to the presence of glauconite and/iron oxides (e.g. goethite). These minerals being absent OL present in minor quantities in the Phosphoria phosphorites while the California and Russian phosphorites carry only moderate amounts of glauconite and negligible amounts of iron-oxide (Bushinsky, 1935; Parker, 1935 and Uietz, et al./ 1942). In the study area* K2O behaves sympathetically with FeO in all types of phosphorite, though the FeO content is very low. The positive correlation of K2O with FeO may be due to the presence of both the constituents outside of the apatite crystal lattices and adsorption of FeO contents during diagenesis of phosphorites (Figure-66). V.3.2.35. K2O vs. AI2O3 The early illite-montmorillonite assemblages seem to have transformed into muscovite, which accounts for most of the K«0 and AI2O2 present in the Hirapur phosphorites (Banerjee, et al., 1982). The association of the pelletal phosphorites accounts for its higher K2O and Al 0- values (Banerjee and Saigal, 1988) . ° 249 + o # UJ o UJ LU CL 1— 1— or Ct oX US o o CL i— CL CL cn CO cr o O < o X X CJ tn CL CL o o > LU Q: Q: 2 00 o a. < O o Q t— N u Z in H- O Q: < u z < LU Qo: :D (/) »-i o «— (N* r^ 250 In the study area, K2O and Al^O^ show a strongly negative correlation in all types of phosphorite samples. This relationship may be due to occurrences of muscovite, sericite, cryptocrystalline and amorphous clay minerals. The high contents of Al2'^3' in these phosphorites may be due to presence of alumina residues and aluminium-phosphate (crandallite) after leaching, weathering and redeposition in the Bijawar basin (Pigure-67), V,3,2.^6. K2O vs. MgO : Howard and Hough (19 79) reported a strongly positive relationship between total alkalies and total CaO + MgO in apatite of Sherrin Creek and D-Tree phosphorite deposits of Georgia basin, N. Australia- Consistent with petrographic data, the pelletal phosphorites are rich in silica, alumina and potassium and contain only small quantity of MgO. In contrast, MgO content is high in stromatolitic phosphorites. Such distri bution pattern has been explained as due to the association of dolomitic and carbonate rocks with the stromatolitic phosphorite nnd abst'ncf* of nuch carbonate nsriociation in the pelletal v.-griety of phosphorites (Banerjee and Salqnl, 198fl). In the study area, the MgO content is poor in all the phoriplu))il.o nniiiril o.n, i (; mny bo r^\^f^ to t\\o nbnoru:n of ntromnlol i tic: bodies; dolomitar. and non-association of carbonate-free content 251 in these phosphorites. However, there is n strong positive correlation between K2O and MgO in the phosphorite samples. Thi.s relotion.'^hlp luny bo due to th^ occurrencey o£ pelletol variety ot: phosphorites ai^d adsorption ot both tht; constituent.-. on the surfaces of apatite during later stages of diagenesis of phosphorites in the basin {Figure-68). V.3.2.37. Ratio CaO/P20^ vs. P20^ : The higher GaO/p 0^ ratios of pelletal phosphorites is difficult to explain in view of the fact that apatite in these phosphorite does not contain free carbonate. Fluorine substitu- — 3 tion for PO^ could be one of the causes of depletion in P^^B content and raise the ^^^/^j^S ratios. Higher than normal F content could be a pointer (Saigal and Banerjee, 1987; Banerjee and Saigal/ 1988). Accompanying this is a less obvious though equally significant decrease in the CaO/P20c ratios ranging from 1.371 to 1.042, a possible reflection of the formation of iron- phosphates at the expense of calcium-phosphates as lateritization proceeded and iron became progressively more available, The distri bution points of the ratio of CaO/P^Oc shows regularly in its patterns and shows distinct possible correlation (Cook, 1972). According to Lucas, et al. (1980) as the phosphorite turns red, its mineralogy changes; CO2 in apatite decreases 252 + o • <3 UJ oQ: UJ a: o ui a. t= in £ '^ Q: O S < o X X U Q- Q- Q. U \f) o UJ X A. Nl < < i/Xi tn ^ fM m Nj 253 ranging between 1.5 and 4.5%; the CaO/P^O^ ratio decreases to 1.30 and the mineral is depleted in both Sr and F. This is a trend towards fluorapatite. The relative amount of clay increases The non-weathered phosphorites is pelletal with an unconsolidated matrix. The apatite is a fluora-carbonate-apatite with 4.5 to 6% in the lattice; the CaO/p20^ ratio is 1.56 (Lucas/ et al., 1980). The GaO/P^Oc ratios varies from 1.14 to 1.32 and also points on the average to rather strong decarbonation characteristic of fluor-apatite (Young, 1969; McConnell, 1938), thus confirming the inf*2rence from the crystallographical analysis (Giresses, 1980). In the study area, the CBO/P-OC ratios varies from 0.71 to 1.50 in shale-phosphorites; 1.03 to 1.38 in secondary phos phorites; 1.23 to 1.33 in ironstone-phosphorites and 1.17 to 1.48 in quartz-brecciated phosphorite samples. The ratios of CaO/P Oc with P^^s ^^^^ ^ progressive positive relationship in all types of phosphorite samples. The low ratios values of CaO/p^Oc supports the absence of stromatolites in phosphorites on the one hand. The low ratio values also support the occurrence of carbonate-fluorapatite in primary (non-weathered) phosphorites and decarbonation and 3ateritization in secondary phosphorites which resulted the formation of aluminous-calcium phosphate (crandallite) in weathered-phosphorite. This trend is indicative of the increasing content of clay in cryptocrystalline to micro- crystalline phosphorite samples (Figure-69 and Table-Xl). 254 V.32.38, Ratio Na20/P205 vs. P2O5 : The difference between the iron-rich and iron-poor Moroccan margin phosphorite samples was discussed at length by McArthur, (1980) who attributed to the difference a greater degree of weathering undergone by the iron-rich samples. The analysis, clearly showed that the weathered samples are lower Sr/P^O^, i^a/V^^c^ and SO^/P^O^ ratios and X-ray CO2. On weathering, Na and SO. must be equally mobile with Sr more mobile than either (McArthur, 1985). A possible negative correlation exists between the Na/P20c ratios of phosphorites from the Meade Peak Member and its depth of Mesozoic burial. There is a good deal of scatter in the data as a result of weathering (Gulbrandsen, 1966) and the fact that sodium from accessory phases appears in the analysis (McArthur, 1985) • In the study area, the ^^2^^^2^S ^^^^^^ varies from 0.061 to 0,114 in shale-phosphorites; 0.002 to 0.023 in secondary- phosphorites; 0.008 to 0,fil2 in ironstone-phosphorites and 0.008 to 0.020 in quartz-breccia phosphorite samples respectively. The plot of ratios of ^^n^^^?^^ values against P^O^ weight percentages shows a progressive positive relationship in shale-phosphorite and negative relationship in secondary, ironstone and quartz- breccia phosphorite samples. Their positive relationship in shale-phosphorite (iron-poor) samples indicated a high intensity 255 in O DT^ (It > O D> 2 's^ o tr> O to ir> O ^ O •>-• Q: c 0)a> in •*-» inO at H- O • <3 '"QT* Q- o Ic in Lrt c *;^ r~ o "•-• o o JS us us ^ OJ Q"3: o .« ^ . .-^ cr or X UJ o o Q_ U) o tz 0- 0U.l < —t- r Q: m 1 o Xo Xo o o a Q_ u o a. a. u m r4 04 l/l in LU O o >- LU a: X z as o or* < o J/) a. Q t— M o en > m LU Z tn »— .o —1 o z cc t2- O < o o < X LU K in or l/l *—1 ^ t/1 C3 '^ "? r- rg r> -sT o ^ O 4-^ in iO a: C o ^in T in crv CO -^ m fN *~ o GO in CM o o o o o o o o o o o O o o o o oO of weathering of the ore and on the other hand, the other three types which they show negative correlation (iron-rich) indicating a mild weathering/leaching of the ore (Figure-70 and Table-Xl)• V.3.2.39. Ratio C02/P2^5 "^s* ^2^5 * The primary phosphatization in Eh independently would suggest a reducing and hence an Eh negative environment of pyrite associated phosphate deposits (Subramanian, 1980). The QO^/VJ^c ratios in Hirapur-Mardeora phosphorite samples varies from 0.047 to 0,123 in shales; 0.019 to 0.050 in secondary; 0.035 to 0.078 in ironstones and 0.032 to 0.071 in quartz-breccia. The ratios of C02/P2^5 values show strongly negative correlation with P2*^5 percentages in all types of phosphorite samples. The absence of pyrite is indicated that the formations of these phosphorites took place in a highly oxidizing environment in the sedimentary basin. The low values of '-Oo/P^^S ^^'^^^'^^ further supported the occurrence of these sediments at continental margins and with contact of granitic basement and decarbonation due to mild weathering from the apatite crystal lattices in ancient period (Figure-71 and Table-Xl). 257 V.3.2.40. Kntio GnO/MgO vn, ^2^b * The mechanism faces the problem pointed out by Martens and Harriss (1970), that the Mg/Ca ratio in sea-water is sufficiently high to inhibit apatite precipitation from the ocean - a conclusion later supported and enlarged on by Atlas (1973)• The role of pH and Eh in phosphorite formation is known only in bare outline. In areas of recent apatite deposition the pH values in the interstitial water of less than 7.5 have persistently been estimated to be 7.2 - 7.4 for Namibia (Baturin, et al./ 1970); 7.4 for Peru (Manheim, et al., 1975). These relatively low values could be significant. The stability of apatite decreases with decreasing in pH, it is still stable at pH/ 7.0, while the carbonates would generally be unstable below pH/ 7.5. A pH below 7,5 would also increase the critical + 2 +2 Mg /Ca - ratios for apatite crystallization (Bentor, 1980), Bremner (1978) concludes that precipitation occurred in shallow and warm lagoons which were periodically disturbed by storm- generated waves. Pellets resulted from the disruption of semi- litihified collophane muds. The warm waters, high phosphate content of upwelled water circulating into the lagoons, high pH from decomposing organic matter and high CaO/MgO ratios would also favour direct inorganic precipitation of phosphate. The direct precipitation of amorphous calcium-rphosphate (Ca/P molar ratio of ^-^ 1.4) in supersaturated solutions of sea J?58 water with normal MgO/CaO ration{Marten and Harriss, 1970; 2+ Nathan and hucas, 1976)• Mg appears to Inhibit apatite precipitation. The cyclicity of the phosphate may have been influenced, among other factors, by the concentration of magnesium in the environment of deposition. The studied phosphate bearing rocks are characterized by a much higher CaO/MgO ratio than the associated non-phosphatic carbonate. The maximum phosphate precipitation occurred when the CaO/MgO ratio was at its maximum. The MgO concentration is shown from solution; high MgO concentration may inhibit apatite precipitation (Simpson, 1966 and Martens and Harriss, 1970). In the study area, the CaO/MgO ratio varies from 25.32 to 119.05 in shale-phosphorites; 109,56 to 215.00 in secondary phosphorites; 22,50 to 357.66 in ironstone phosphorite and 19.51 to 93.12 in quartz-breccia phosphorite samples. The plot of ratio of CaO/MgO with Po'^s Percentages values show a negative correla tion in all types of phosphorite samples. The high CaO/MgO ratio values indicated the mechanisms of inhibit apatite precipitation from the ocean; supports the pH of the basinal waters around 7.0; occurrences in shallow, warm, lagoons which may be periodi cally disturbed by storm-generated waves; pellets resulted from the disruption of semilithifled cellophane muds and favour diagenetic inorganic precipitation of phosphate by warm upwelling sea water currents in the Bijawar basin (Figure-72 and Table-Xl). CiJu SUMMARY s The critical study of the distributions and geochemical relations among the 13 major constituents of the phosphatic rocks of the study area led to author to believe that most of the ores are in the primary state and deposited syngenetically with the host rocks through authigenetic process. In the secon dary ores that are mostly derived from the primary ores through eustatic sea level changes, actions of sea waves, tides and currents and groundwater, the most of chemical constituents have same trend of distributions and relationships as that of primary ores. The phosphatization might have taken place in a fairly oxidizing to slightly reducing environment, supratidal to inter- tidal/ continental margins and on the shallower parts of the basin, tropical to arid climate, high alkaline, marine, struc tural and stratigraphic controls, upwelling currents and restric ted circulation of water. The formation of epigenetic secondary phosphorites was mainly due to lateritization and indicated by the concentration trends of each elements. There are innumerable cases of absorption and adsorption and partial replacement of certain minor elements out and inside the crystal lattices of apatite. The narrow and wide variations in the concentrations of certain elements attributed possible mild leaching of the E60 syngenetic ores. The formation of crandallite (calc-aluminium phosphate) in the epigenetic ore samples may be due to ionic +2 +3 substitution of Ca by Al inside the crystal lattice of apatite« It is apparent that the transferred concentrations or leaching of certain minor elements from the priirary phosphorites to the secondary ores where largely dependent on the absorption and adsorption capabilities of the secondary or primary minerals 281 CHAPTER - VI TRAf?F MRT&T. nT55TRTnnTTnN AND THEIR CORRELATIONS VI,1> GENERAL STATEMENT t The term 'Trace elements* includes certain chemical elements whose total amounts in the earth's crust is very small and which are encountered* as a rule, in small amounts in rocks and minerals as isomorphous impurities, rarely forming minerals in their own right. The chemical elements like uranium, nickel, cobalt, chromium, vanadium, copper, lead, gallium, etc., the content of which in rocks is rather appreciable and which form many minerals of their own are frequently known as 'Trace Elements'• Apatite are capable of concentrating considerable amounts of different trace elements (Cossa, 1878; Swaine, 1962; Tooms, et al.# 1969; Gulbrandsen, 1966; Altschuler, et al.# 1967; Kholodov, 1973; Calvert, 1976; Altschuler, 1980; Prevot and Lucas, 1980 and McArthur, 1990). AS pointed by Toams, et al. (1969), the trace element pattern is a function of two factors - a crystal chemical one - the capability of the apatite lattice to accept foreign ions and a geochemical one - the availability of these elements in the environment of the apatite formation. 262 In generals iron formations show low concentration of trace elements relative to other sedimentary rock (Davy/ 1983). In contrast* the wide spectral trace elements content of the Bljawar iron formations may be attributed to incorporation of clastic components in the B«G«A. rocks (Bandhyopadhya and Roy# 1987) . Green (1959), Russell and Trueman (1971), Cook (1972) and Gulbrandsen (1977) states that the phosphorites from thei Phosphoria Formation is enriched in Se, Cd, Ag, U, Sb, Mo, As, Rh, Cr, Zn, Th, Hg, V,REE, and sn. Altschuler (1973) also lists Ag# I# La* Mo. Sb, se, Sn, Sr, U and Y as being enriched in world phosphorites. Fixation of most trace elements on the algal apatite was either through the adsorption on the surface of the apatite or by the substitution in the apatite lattice (Riggs, 1979; Banerjee, et al.# 1984). According to Davidson and Atkins (195 3), Heinrich (1958), Betekhtin (1959) and Dar (1970), aluminium-phosphorites (wavellite and turquoise) can be uraniferous due to u"*" substituting Cu in turquoise (Cu, Alg(PO^)^(OH)g.5H20) and Ca"*"^ in crandallite. Studies of contemporary phosphorites indicate that these deposits were formed under low Eh conditions (Kazakov, 1937; Kajitani, 1968; Burnett, 1974; Veeh, et al.# 1974). Consequently, a major percentages (usually greater than 50%) of the incorporated uranium in the reduced, U(IV), oxidation state (Spalding and Sackett, 1972). E63 Uranium in phosphorites has been shown to occur in mixed oxidation states, i.e. both tetravalent and hexavalent uranium are contained within the phosphorites (Goldschmidt, 1923 and 1937; Dietz, et al., 1942; Clarke and Altschuler, 1958; Altschuler, «t al.# 1958; Kolodny and Kaplan, 1970 and Burnett, 1974; Avital, et al., 1983). The uranium is almost entirely contained within the major mineral phase, carbonate-fluorapatite termed francolite (McConnell, 1958). All the important mineral deposits including lead-zinc sulphide, phosphates, copper and uranium, are carbonate-hosted and are confined to the marginal shelf sequence showing a diverse lithofacies association (Singh, 1988). Uranium, cesium and yttrium probably reside almost entirely within apatite Is possible contributing phases are virtually absent. Goethite may possibly contribute to the content) of U, Ce, Y in some san?)les (McArthur, 1978 a, b). The phosphatlc rocks were deposited as part of the Lower and Middle Proterozoic sequences after the atmosphere became oxygen-rich could be enriched with U-mobilised in u"*" state from the U-rlch provenance and carried out and. concentrated in favourable reducing environ ment. These horizons generally occur above the Iron Formations in the Proterozoic stratigraphic sequence (Mahadevan, 1986). Vanadium is a member of the iron family like nickel (Goldschmidt, 1923). In the marine phosphorites of Idaho, U.S.A./ the vanadium content has been reported to be upto 1300 ppm 264 (Jacob, et al., 1933) as vanadium is one of the more abundant trace element in the phosphatic rocks of Idaho. In the carbonate rocks Its concentration, variess from traces to 3000 ppm (Ostram, 1952; Runnels and Schleicher, 1956 and Graf, I960). Higher concentration of vanadium is partly explained by the abundance of clay minerals; organic matter present in the pelletal phos phorites may also have acted as the sink for vanadium (Banerjee, and Saigalr 1988) . V, Cr and Cu (partially) are associated with the clay minerals which determine the stability of the primary assemblages in the supergene enrichment. Elements that are mobile in the supergene zone (Cu, Ni, 2n and As) are partially lost from the phosphorite bearing beds and are partially taken up by iron- hydroxides, clay minerals and carbonates (Proshlayakova, et al.# 1987). Bliskovskiy (1969) found the vanadium level in the phos phorites in the KarSatau basin as 52 ppm, which is approximately less than the Clarke value for sediments. At the Dzhanatas deposit the V level in the cherts is 40 ppm, and in the phosphorites 11-13 ppm (Krauskopf, 1955, 1956^ b; Kholodov, 1973; Mohammad, et al.# 1981; Proshlayakova, et al., 1987), In sea water, nickel most probably prevails as dissolved species mainly as nickeleous ions, as either aquato or chloro complexes (Tooms, et al., 1969). The Ni levels in the formation are less than the Clarke value, although less than for Cu; the maximum is 100 ppm in a siliceous phosphorites. Ni distribution 265 is blmodal and is similar to that for Cr (Proshlayakova, et al.# 1987) • The elemental mobility in secondary oxidizing and acidic environments can be generalized as low as for Pb, Ag and Cr and as high for the trace elements, Cu# Zn, Ni and Co« When the relative mobility for an element is low, the observed concentra tion of that element is bound to be high (Roonwal and Kunar, 1987) • The Ba# Th, Ce, Ni and Sr substitute for eleaents in the clay structures or an adsorbed onto clay surfaces (Howard and Hough, 19.79) • Trace elements showing a similar trend inclcde, Ba, Co, feu, Li, (?), Ni, Pb (7), Rb and Zn - all of which are believed to be located outside the apatite lattice. Their increase in concentration in some instances may result from the insolubility of the host mineral but in general it is probably the result of introduction during the course of weathering (COo)c, 1972). Mason (1966) suggested that Cr usually behaving as a +3 highly lithophile element, occurs in rocks as Cr . During dis integration and weathering of rocks, Cr**" has little mobility and its behaviour is similar to that of Pe , concentration or of Cr in phosphate deposits has been reported variedly in various parts of the globe and in deposits of varied ages (Roonwal and Kumar, 1987). Krauskopf (1955) has reported the Cr content from 30 to 400 ppm; Gulbrandsen (1966) upto 1000 ppm in the Phosphoria Formation of U.S.A.j Khan (1978) upto 165 ppm. in the Pithoragarh 266 phosphorites of U.P. (India) and Viqar (1981) from 30 to 200 ppm in the Birmania phosphate deposits of Jaiselmer (Rajasthan^ India • The Cr levels in the Chulaktan formation are below the Clarke values for sedimentary rocks• Bliskovskiy (1969) found that the phosphorite beds had 20-120 ppm with an average of 50. At the Dzanatas deposit the mean Cr content is 61 ppm and the values very little in the supergene zone, A bimodel distribution appliesi- the c/arbonate rocks and cherts are relatively enriched in Cr (Proshlayakova, et al.# 1987). Carobbi and Pieruccini (1947) noted that due to similarity of Cu"^^ (0.83 Kx) and Fe"^^ (0.83 Kx), Cu"*"^ replaced Pe^"^ and MgT^ 4-2 Krauskopf (1956) has shown that Cu is effectively adsorbed by Pe(0H)2# Mn(OH)o and clay minerals. Copper has similar mean contents in all the rock types but with a minor to maximum in the cherts, the levels being appreciably below the Clarke value for sedimentary rocks. The elemental mobility in secondary oxi dizing and acidic environments can be high for trace elements like, Cu, Zn, Ni and Co. When the relative mobility of an element is low, the observed concentration of that element is bound to be high (Roonwal and Kumar, 1987 and Ghosh, 1988). Copper and uranium are carbonate hosted and confined to the marginal shelf sequence (Singh, 1988). Association of Cd with ferruginous minerals and organic matter is well )aiown. Among the deposits under present study^ Cd is found to be maximum in the Bijawar phosphorite of Hirapur. 267 These phosphorites are devoid of any organic matter, hence the associated iron-hydroxides of the Hirapur phosphorites seem to act as sink for Cd. The presence of Cd can be explained as due to adsorption on the apatite surface during diagenesis or by virtue of their affinity for certain associated elements (Saigal and Banerjee, 1987). Gallium is both basic and acidic and has an ability to form alums such as (NH^)2 SO-.Ga2(SO^)2.12H20, which are isomorphous with Ai , Zn"*" and Pe"*" • Similarity of chemical properties as due in part to a similarity of the radii of Ga (0,52 A*^) and Al"^ (0.57 A°) (Boisbrandran, 1875). High contents of Pb are similarly attributed to sulphides by Bliskovslciy (1969^ a) who proposed that the normative lead is fixed by adsorption on the marine apatite. There is a Pb peak in the supergene zone in the phosphate-rich rocks, whereas the unaltered rocks have the maximum Pb in the clayey-phosphatic- siliceous shales (cherts) (Ramsay and Easily, 1983; Proshlayakova et al-* 1987). The elemental mobility in secondary oxidizing and acidic environments can be generalized as low for Pb, Ag# and Cr (Roonwal and Kumar, 1987)• These elements are concentrated by chemical precipitation in the reducing environment created by organic sedimentsjby adsorption on clay particles, colloidal gels and organic debris; and by organic processes such as bacterial action (Gold, 1954). Nickel in spite of its low abundance in phosphorites (50 ppm) 268 behaves almost like vanadium. It is, however, a less evident substitute in apatites, which may explain its lower concentra tions. Its concentrations increase when phosphorites contain glauconites or iron-oxides (Debrabant and Paquet, 1975; Lucas, et al., 1978) • Uranium has been deposited under euxinic conditions at the base of biohermai limestones. It has been found that uranium and Cu sulphide mineralization are antipathetic but they are generally adjacent in the same formation (Verma, 1980 and Al- Bassam, et al., 1983). The other mobile elements were leached and removed from the rock masses, Cr was redistributed within the sediment package. The iron-oxides and hydrated iron-oxides in weathered phosphorites of Hirapur and Matoon seem to have entrapped considerable amounts of Cr. Besides Cr, phosphorites are comparatively richer in clay- minerals and seems to have offered possible sites for the entrap ment of Cr in the rock» Most of these observations are adequately supported by the fact that all other Proterozoic phosphorites of India lack clay minerals, hence are very poor in Cr» Cr substi tution for P is theoretically possible, but no apparent proof could be cited at this stage of investigation (Banerjee, et al.# 1984; Saigal and Banerjee, 1987) . Both V and Cr may be concentra ted in iron-oxides and hydrated iron-oxides and clays at higher concentrations in the weathered phosphorites of the Sey-brinsk 269 region (Gulbrandsen, 1966; Blisskovskiy, 1969). Both the elements may# therefore, serve as Indicators of general mineralization in •red bed* environments (Boyle, 1984). some shales devoid of phosphatic nodules in Oklahoma and Kansas, U.S.A., contain U^Og but with the appearance of phosphatic-nodules, uranium content increases (McKelvey and Nelson, 1950). Swanson (1960) has compared P2*^5 ^^^^ ^3^8 content of phosphatic rocks of Montana and has shown that even the high grade phosphorite (31% ^o^S^ ^^ ^^^ contain more than 0.012% ^2^Q* Elliot (1968), Nathan and Shilloni, 4976J and Viqar, (1981) reported an increasing trend between U^Og and ^2^5 ^" ^^® phosphorites of Israel and Birmania# Rajasthan (India)/ although in most investigators did not find a close correlation not between the two. A positive explanation for this anomaly is that the limiting factor for incorporating uranium in apatite is not crystallographic saturation (all phosphorites are undersaturated in this respect) but the amount of uranium in sea water (inters* tial water) from which the phosphorites precipitates. The uranium content of the water together with the partition coefficient determined the uranium content of the phosphorites. This effect is particularly important in high P2^5 ^ocks. According to PettiJohn (1975) the range of Eh varies from 0.00 to 0.50 and that of pH from 5.10 to 8.00 for the precipita tion of phosphorites and Eh, - 0,00 to -0.50 and pH, 5.00 to 7.10 270 for U3O . In the phosphorites, the U-content increases roughly ih proportion to an increase in the phosphatic content, implying that the uranium is contained in a phosphatic minerals. The depositional environment of uranium bearing black shales and the phosphorites is characteristic of low lying, stable areas, where the influx of clastic material is small. The precipitation of uranium in carbonaceous black shales may be brought about by chemical adsorption on apatite, as living or dead plankton (McKelvey, et al., 1955; McKelvey and Carlswell, 1956; Berzinia/ et al., 1978; Starinsky, et al., 1982) and by reduction of U"*" 4-4 ions to the less soluble u ions through the action of bioche mically generated H^S (Goldschmidt, 1954; Jensen, 1958; Mason, 1966 and Slansky, 1979)• There are more complicated substitutions, such as Si + S for P; Cr"*"^ + 2cr'''^ for 3?'*'^ (Minguzzi, 1941; Heinrich, 1954). Frohlick {I960) proposed that Cr in the modern sediments is concentrated in the clay minerals and micas, v^ile Prevot and Lucas (1980) proposed that Cr is primarily carried away by the apatites and is further fixed in/on clays when these are presents in the sediments (Singh and Subramanian, 1988)• The plot of Cu, Cr and extractable F in the sediments with the extractable P shows positive relationship and indicate that all these elements have common source, namely the phosphate mineral phase in the alluvial sediment sink in the Doon valley (Singh and Subramanian, 1988). Fairly complete substitution for 271 +2 Ca has been demonstrated for si^ Ba, and Pb for the halldes and for hydrophosphates by Kreidler and Hummel (1970) and Altschuler (1980). Background valiiies of uranium and thorium in 371 clastic sediments from the Catskill Formation of Pennsylvania* U»S.A. correlated negatively with SiO^ and positively with AI2O- and most other major elements because of the low content of uranium and thorium in quartz and their relative enrichment in clayS/ iron-oxide and other fine-grained components (Pric and Rose, 1981). In the acidic environment associated with natural waters, uranium oxides are most soluble in CO^ containing solutions of sodium uranyl tricarbonate (10 gm/litre) . A decrease in the CO^ concentration of the solution results in uranium precipitation. An increase in alkanity somewhat impedes uranium precipitation (Tugarinov, 1975). Alder (1970) suggested that the oxidation- reduction conditions started due to arid climate and having -2 (SO-) content in water resulting in the precipitation of phosphatic iron-ores during high redox-potential conditions besides the incorporation of U^O- by iron. A characteristic element in marine phosphorite is uranium which ranges in value from a few ppm to about 500 ppm with a mean of the order of 80 ppm. Maximum values are observed in the Chatham Rise, Off New Zealand (Cullen, 1978). Phosphate nodules exposed to oxidizing conditions and currents at the sea-floor may have the more insoluble U(IV) compared to oxidized U(VI) 2.11 and leached away« depleting the sample in uranium (Altschuler, et al.# 1958; Burnett, and Gomberg, 1977). Burried phosphorites generally retain uranium proportions and maintain a sufficiently constant U/P2O5 ratio such that prospecting for phosphorites by gamma ray logging is a highly effective and sensitive technique. Still higher uranium concentrations have been reported from terrestrial phosphorites and some of the enrichment is attri butable to remobilization or reprecipitation of uranium in the groundwater zone (Force, et al.# 1978). It is observed that P^^^c ^as ^ strong tendency to be associated with ^^2^2 ^^ n^any aquatic environment. Bortleson and Fred Lee (1974) have shown that ^^2^3 ^"^^ ^2^5 ^^® positively correlated in lake sediments and that the oxidation conditions will control the rate of Fe-O. in either mobilizing or releasing ^2^5 ^^ ^^® water. Subramanian (1976) has shown that ^^2^3 ^^ ^2^5 ^^^ oogenetic in fresh water as well as in estuarlne environ ment and Nriagu (1972) has e3q)erimentally verified the role of ^®2^3 ^° ^2^5 ^^^^ transfer in the aquatic environment. In a very high oxidising environment, Fe removes P**" from water by the formation of sorbed complex on Fe(0H)2 there by making available 3 +2 only a small amount of (P0^)~ for Ca to form apatite in the marine environment. Hence, for the continent derived P^Oc ^o reach the ocean for apatite precipitation the river should have positive but not extreme oxidizing and acidic conditions; any change in these parameters may trap the dissolved POT in the 273 estuarine region where the P^^c couid be sorbed by Fe(oH)- or clay minerals. VI^2; TRACE METAXi DISTRIBDTIONS s The geographic distributions of trace elements in the shale phosphorites, secondary phosphorites, ironstone phosphorites and quartz-breccia phosphorites of Hirapur-Mardeora area is given below :- VI>2.1, Uranium Oxide (1X3Qg) s In the study area, uranium is the most dominating trace element and others are very low in the phosphorite samples of the Bijawars. Surprisingly the deposits have no uraniferous- phosphate mineral as studied with the help of X-ray diffraction. The uranium content is higher in the seccmdary phosphorite samples than in the primary phosphorites (shales, ironstones and quartz-breccia). The element varies from 0*005 to 0.105% in shale; 0.083 to 0.13% in secondary phosphorites; 0.049 to 0.069% in ironstones and 0.003 to 0.103% in quartz-breccia phosphorites. It is suggested that the a) uranium migration and distribution took place during weathering and sedimentation in the tetravaLent (U ) to hexavalent (u"*" ) stages in the highly oxidizing to e aCL. 274 4- O • <] UJ V— (X o UJ Q. UJ U) O a X UJ e g OL (/) tn 01 o o X o X a o £ u tn a. Q: o >- UJ Ol X '< £D o C u N 10 o o cr < o < CO UJ c/X l t/> v-» c33 o 3 •— (^ ro c o 3 Q to UJ cr CD E75 reducing conditions of the basinal waters (see Goldschmidt, 1923, 1937; Dietz, et al., 1942; Clarke and Altschuler, 1958; Altschuler, et al.# 1958; Kolodny and Kaplau, 1970 and Burnett, 1974) • b) Uranium content is perhaps loc^lked up in the iron- oxides, phosphatic-gels and crypto-to microcrystalline masses of clay-minerals; and it may be due to adsorption (see Graf, 1960 and Cook, 1972), c) It may be possible that the minor content of uranium might have substituted with the phosphatic content during complex geochemical sedimentary process (deposi tion, weathering, migration, leaching and redeposition) in the basin-sea (see McConnell, 1958) • d) On the basis of above observation (O, it may be deduced that cellophane and cranda- llite might have fairly or highly radioactive due to uranium occurrences (see Dar, 1970). e) It is also suggested that the uranium mineralization took place in the marine, shallower conditions and above the Gangau-Ferruginous Formations of the Bijawar Group in the Proterozoic basin (Mahadevan, 1986 and Singh, 1988) (Figure-73 and Tables-IV and V A). VI>2^2> Vanadium (v) s The vanadium content is almost low in all the four types of phosphorites in the study area. It varies from 98 to 172 ppm in shales; not detectable to 25 ppm in secondary; traces to 276 101 ppm in ironstones; not detect^ible to 105 ppm in quartz- breccia phosphorite samples. The poor concentrations of vanadium in the phosp^iorites may be due to weathering and/leaching of vanadium from the ores by circulating groundwater action or poor supply of the vanadium from the source rocks or inproper mutual substitution of pentavalent ions of phosphorus (P ) by vanadium (V"^ ) or adsorptions of vanadium content by uranium in the ferru ginous concentrations, phosphatic colloids and clay minerals in the oxidizing to reducing conditions of the marine, shallower conditions of the basin (see Banerjee and Saigal# 1988) (Figure- 73 and Tables- IV, and V,A). Wl.2.3. Nickel (Ni) : Like vanadium, nickel concentration is very low in all types of phosphorites except ironstones phosphorite samples• It varies from 9 to 152 ppm; not detectable to 159 ppm: 50 to 1129 ppm and traces to 361 ppm in shales# secondary, ironstone and quartz-breccia phosphorites respectively. The higher concentra tion of Ni in the ironstone phosphorite samples may be due to chemical affinity with iron which supported the idea of Goldschmidt (1923). The presence of Ni in these sediments may be due to mutual ionic substitutions of trace elements during high oxidizing marine conditions of the basinal waters. It may be possible that like vanadium, nickel was also adsorbed in the ferruginous minerals. + o o < LU a 0 LU LU (/) »— t— 0 o: Q: X UJ o £ — inQ_ a> < QC o 0 o X X u Q-. Q. a u if)O w X > LU Q_ g < 0 Q t— M LU 2: •— -J 0 v2> Q: < <_) 0 < X U oc 3 fN ro vj m clayey masses and phosphatic and siliceous gels* It might have also been introduced during the sedimentation processes which formed ccanplex geochemistry of the sediments* It is also suggested that the minor content of Ni may be located on the outside of the apatite crystal lattices (Cellophane and crandallite) (see Cook, 1972; Howard and Hough, 1979; Proshlayakova, et al., 1987 and Roonwal and Kumar, 1987) • (Figure-74 and Table-IV, and V, A) . VI*2*4* Chromium (Cr) t Chromium concentrations in shales varies from traces to 215 ppm;in secondary deposits, not detectable to 300 ppm; iron stone, traces to 692 ppm and quartz-breccia, not detectable to 408 ppm respectively. The higher content of Cr is present in the ironstone phosphorite samples and it supports the observations of Mason (1966) and Roonwal and Kumar (1987) that Cr behaves similarly with Fe in the phosphorite deposits. The lower content of Cr is also supported the less mobile nature of this element after disintegration and weathering of the rocks. On the other hand, the lower values of Cr in the secondary phosphorite samples further support the above observations (Figure-74 and Table-iv and V^A). o Q o o lO o in -^ ^ + 0 • <1 UJ o Q. UJ UJ (A a: t: o o UJ Q_ o 0- CL «^ X ^ O< QL Q- o U- UJ X CC 9 ^ CD X cr a. < o ui tn •- (N rn '^ o o o o in o 3 O X80 VI^2.5. Copper (Cu) t Copper concentration Is also low as like other trace elements in the phosphatic rocks. It varies from traces to 104 ppm in shales; not detectable to 295 ppm in secondary; traces to 192 ppm In ironstones; and traces to 305 ppm in quartz-breccia respectively. The low content of copper may be responsible for the absence of pyrite. On the other hand, it may be also possible that these sediments were formed during highly oxidizing condi tions. One more possibility is that due to the absence of sulphate (SO-) ions in the water, the pyrite could not be formed at the time of phosphatization. The minor content of copper may be due +2 +2 +2 to mutual ionic substitution of divalent Cu by Fe and Mg during oxidizing conditions of the basin. Some of the copper content may be adsorbed on the crystal lattices of collophane, crandallite, clay and iron bearing minerals. The higher concen tration of copper in a few samples of the phosphorites may be due to insoluble nature of this metal and copper might have been introduced during the processes of leaching and weathering of the ores (see Carobbi and Pieruccini, 1947; Roonwal and Kumar, 1987; Ghosh, 1988 and Singh, 1988) (Pigure-75 and Tables-IV and V, A). zn VI,2.6, Cobalt (Co) s In the study area# the Co content is lower in primary phosphorites than in secondary phosphorite samples. It varies from not detectable to 113 ppm in shales, traces to 502 ppm in secondary; not detectable to 161 ppm in ironstones and traces to 165 ppm in quartz-breccia respectively. The occurrence of Co in all the phosphorite types may be due to presence of ferruginous content in all the phosphorite samples and this supported the closeness of Co with iron. The occurrence of Co in these sediments may be due to adsorption of minor content in the fine crystalline masses of phosphate, clay and iron bearing minerals. In the secondary phosphorite samples, the much higher content of Co may be due to leaching and weathering of the ore in which the detrital as well as gangue minerals removed during diagenesis (see Howard and Hough/ 1979 and Banerjee and Saigal, 1988) (Figure-75 and Tables-IV and V, AK VI.2.7. Zinc iZn) : 2n varies in phosphatic rocks from traces to 550 ppm in shales, traces to 635 ppm in secondary, not detectable to 260 ppm in ironstones and not detectable to 200 ppm in quartz- breccia respectively. The higher concentration of Zn in primary E a. zn + 0 U Q: 0 (/I u lli V— 0 — ^_ X or cr •CL UJ o 0 LLI a. Q. CO o tr LO to < Q: O 0 o X X 0 Q- Q_ Q. C_) T3 01 UJ C on o UJ m Q- f: ixi < 0 UJ 2: u> V- CL 4 ~-J 0 z: cr < u 0 < X LJJ cr z> < 1/1 (/I i-« O en o •- fM 2 o CQ or I— in Q UJ ct: CD E83 phosphorites samples may be due to high oxidizing conditions of the basin. On the other hand in the secondary phosphorites, the much higher conte.nt of the 2n may be due to leaching and weathering of the ores. The Zn content may be adsorbed by clay particles or apatite crystallites and others possibly entered in the apatite lattices. This element may also associated with higher ferruginous content and confined to shallower parts of the basin (see Green, 1959; Cook, 1972 and Bandyopadhya and Roy, 1987) (Figure-76 and Tables-IV and V, A). VI.2.8. Cadmium (Cd) s In the study area, the Cd values varies from not detec table limit to 179 ppm in the shales; 110 to 610 ppm in secondary; traces to 230 ppm in ironstones and traces to 165 ppm in the quartz-breccia phosphorites samples respectively. The association of Cd in the study phosphorite samples may be due to adsorption on the apatite surface, ferruginous and clay minerals. Its presence may be also due to occurrences of other trace elements within and outside the crystal lattices of the cellophane and crandallite phosphate bearing minerals. 'Rie above observations regarding the Cd occurrences further supported the studies of Saigal and Banerjee (1987) (Figure-76 and Tables-IV and V^ A) . b ex. ex a. 84 -f O • < a QoL u UJ t/> t: o t= a: X a: o OL Ui o Q. D_ in 10 < o o X X u s CL Q_ u ID u O Q: U GQ CL z: < o N Q U z: o z Q: < u < Qo: Q X UJ t—1 If) IT) c .— rj m 285 VI,2,9> Gallium (Ga) : The Ga content is almost very poor in primary but little higher in secondary phosphorite sartples of the Hirapur-Mardeora area» It varies from traces to 22 ppm in shales; not detectable limit to 290 ppm in secoridary; not detectable limit to 38 ppm in ironstones and upto 29 ppm in quartz-brecciated phosphatic rocks Their presence in all types of phosphorite samples may be due to isomorphous nature and similarity of the ionic radii of Ga"*" and Al • On the other hand, the Ga might have arrested/captured by clay fractions and iron-oxides of the phosphorites (see Bois- brandran, 1875)CFigure-77 and Table-IV and V, A). VI.2,10.Lead (Pb) s The association of Pb in the phsophatic rocks is very poor as compared to other trace elements. It varies upto 37, 17, 22 and 12 ppm only in the phosphatic shales, secondary, ironstones and quartz-breccia respectively. It may be suggested that the minor content of Pb"*" might have been replaced by Ca"*" in the highly oxidizing conditions of the marine environment (see Goldschmidt, 1923). It may be due to epigenetlc mlnerali- 235 238 zation and disintegration of U and U into radiogenic Pb CO 286 / O fn / o 3 a> + c01 Q) o + / / /. / -H + O • <1 / / £ CL O u + ho / > O Q: / UJ o / CL / 5 o o or u o X OL a. GE o o o X < QL X a. a. u / o / o o o u / / >- UJ / cr Oi 2 L -I— < O o ^ - - s 2 t/1 »— 6 6 6 2 —J O 2 cr 6 6 c < U o < 5^ X u cc ^ o U) U) 1—• c r O 3 CO T- (M m o 3 O )- o 0" c / 0) // o cu h o / / / r / ^ / / / / £5 / r / / "3 / 0 o or / / / rn / ^ / UJ / / cr / / / / / CD + .^ —r- —} 0£/ 1 1 1 i"r o CO £• sJ 5 § S o 6 o o 00 O 3t o 287 (see Bllskovskiy, 1969^a and Ramsmy and Easily, 1983). This Pb may be adsorbed in the gangue constitaents of the phosphorite rocks (see Cook, 1972 and Roonwal and Kumar, 1987) (?igure-77 and Tables-IV and V, A) . VI.3. TRACE METALS CORRELATIONS S Here the author will discussed in detail the geochemical behaviours of trace elements in the phosphate bearing rocks of the study area» VI,3.1. U3OQ vs. Ni t Both uranium and nickel show weak negative correlation in tne phosphatic shales^ secondary, ironstones and quartz- breccia samples. The higher concentrations of uranium and nickel may be due to adsorption by ferric-oxides, ferruginous and clay minerals and on the surfaces of apatites. The negative relation ship between these elements may be due to mutual ionic substi tution during high oxidizing^marine conditions of the basin before the precipitation of apatites (see Debrabant and Paquet, 1975 and Lucas, et al., 1978) (Pigure-78). (J o in E88 - ^ > J- a? O in 3 o -in c - e o CL OJ jQ + 0 D U - UJ o 10 -in a: c o o Q- " UJ j2 a: cc o Q: o o in QL bo < • * tr Xo Xo O QoL CL o if) a. oUJ LL o >- UJ n. < Vo— Nl UJ u2 (/> »— —J o z Lt < < 1 X o o Z> / UJ cr o tn (/) / / • o / / CO — rj m / / O o / / o / r- E C / / / / o / k o 0) / in O -O / a. / o ]E / o < • o (n <3 c /+ /< / O / • o / •t- o a: > 4^ -f oo r- J- O 00 O o o o O 6 6 o o CD 09 O 289 V>3«2, U^OQ VS> V : In the Hirapur-Mardeora area, the organic content in the phosphatic rocks is negligible/complete absent. Thus, the organism did not play any significant role to create a reducing environment during the formation of these sediments. The occurr ences of large masses of clay and ferruginous and phosphatic minerals and their colloidal gels may-be'responsible for the adsorption of these trace elements. The weaker negative correla tion between uranium and vanadium indicated that perhaps there was not a proper mutual substitution of these elements in the apatite crystal lattices during the inorganic processes of the phosphorites (see Gold, 1954) (Figure-79). VI.3.3. U^OQ vs. Cr : Also, chromium :. y. behave like V and Ni with uranium in the phosphorite sanples. Cr shows antipathetic relationship with uranium in all the four types of phosphorites. Cr might have been adsorbed or by with U in the gangue of phosphorites as like other trace elements. The weaker negative relationship indicated the incoiT5>lete mutual substitution of these two elements in the apatite crystal lattices (see Howard and Hough, 1979) (Figure-80). 290 VI,3,4, U^OQ V3> CU Uranium and copper are both associated with phosphatic shales, secondary, ironstones and quartz-breccia but not with limestones. On the other hand, there is no bio-hermal limestones and iron and copper sulphide (pyrlte) mineralization in these sediments. Thus, the progressive positive relationship between vraJaAusf} Aod cc^ppBr AJ? th& s^xsples of phosphatic shales. Ironstones and quartz-breccia indicated the formations of these rocks during high oxidizing to reducing, marine and shallower conditions of the Proterozoic basin. It is also suggested that during the above geochemical environment of the ba^in, there might be mutual substitution, though on minor scale, of Ca by Cu and of ?•*• by u"*" in the apatite crystal lattices. The progressive weaker negative relationship between U and Cu in the samples of secondary phosphorites may be cJue to leaching and lateritic lateritization generated by grounclwater action. The weathering, remobilization and redeposition o$ these phosphorites were perhaps been responsible for the Enrichment of secondary uranium (see Verma, 1980; Al-Bass^m, et al., 1983)(Pigure-81)• VI.3.5, U^QQ vs.Pb The progressive weak posit;ive correlation between uranium and lead has been plotted in the primary phosphorite O :^ E9t c £ CD (X + 0 a. J2> O a. »— a c o o UJ (A ^- O X • (X Qo: Q. o 00 X U a. U o U UJ cr a. cc < O GO *^ ^~ r^ r^ :«2 O aE. a. C c 0; 00 29E samples (shales# ironstones and quartz-breccia) and negative correlation in the secondary phosphorite samples respectively. The type of .geochemical relationship between the elements in these sediments supported the depositional environment accompanied by sedimentary processes during phosphatization as seen in between uranium and copper (see Howard and Hough, 1979)(Figure-82). VI.3.6. V vs. Cr s Vanadium and chromium in the primary phosphorite samples of shales and quartz-breccia show weak negative correla tion but on the other hand they show strongly positive relation ship in the samples of ironstone phosphorites. However, no correlation between the two is detected in the secondary phos phorite samples. The negative correlation perhaps indicates that Cr"*" may be replaced by V during highly oxidizing conditions of the basinal-sea waters and on the other hand a positive relationship between the two elements supported the affinity of Cr with Fe in the ironstone and also phosphorites. These elements may be adsorbed in the iron-oxide, ferruginous and clayey fine-grained minerals during phosphatization processes. In the secondary-phosphorite samples, the absence of any relation ship between these two elements may be due to weathering and/ leaching of the ore by groundwater action (see Gulbrandsen, 1966; Bliskovskiy/ 1969; Banerjee, et al./ 1984 and Saigal and Banerjee, 1987) (Plgure-83). o o to o •4- > O c E + o • < a. 5 O a. a; in o J3 O UJ cr o 0 In a. m w u UJ in c ^ »- o o cr cr X LJJ o a. 1— £ tn (A o O < (r 5o X X u Q. a.- u Co o UJ oo X >- Ui < o o h- NJ LU z (A H- ~-l o 2 a: < o O < X UJ cc 3 Vl tn f^ C3 fM ro ^ E ex. C a; J3 c o 00 CD o to L) \ J- \ in \ > \ o \ in \ CO •V 0 • fM ro in > c t a; CL O icn o JO Q) OO O LL £95 VI>3,7. V vs, Nl s V correlates negatively with Ni in all types of phos phorite samples. This correlation between these two elements further supported the occurrences of these elements in the marine environment and adsorption by the gangue constituents of the phosphorites (see Krauskopf, 1955; Gulbrandsen, 1966) (Pigure-84). VI>3,8. V vs. Co : Vanadium behaves negatively with cobalt like Cr and Ni in all types of phosphorite samples. Thus, the above observation further supported by this type correlation in the Hirapur-Mardeora areas (Figure-85). VI.3.9. Ni vs. Cr I The natural affinity of Cr for the group of elements like V-Ni-Cr-Zn is considered to be typical of organic matter (Saigal and Banerjee, 1987). The progressive positive relationship between Ni and Cr supports the elements association group in the phosphorites saatples suggested by Saigal and Banerjee (1987) (Figure-.86) . E96 S :^ £ S + o VI,3,10. Ni vs* Cu : The weaker progressive positive relationship between Mi and Cu in all types of phosphorite samples supported the trace elements groap associations In these marine sediments. It is also suggested that these elements in the phosphorites may occur as *traped ions* (see Krauskopf, 1955; Gulbrandsen, 1966 and Saigal and Banerjee, 1987) (Figure-87). VI>3>11> Mi vs. Co s The weaker and/or poor positive relationship between Ni arid Co supported that the Co ionic radii differs from those of phosphorus and it is not so easy to accommodate Co in the apatite structure. The weaker relationship between these elements also indicated that adsorption by means of higher content ox iron and clay and elemental group associations in these phosphorites. This relationship also indicated the formation of phosphatic sedi ments in the 'red bed* environments (see Gulbrandsen, 1966; Saigal, and Banerjee, 1987 and Boyle, 1984). (Pigure-88). VI.3.12^ M \rs. gd 3 The progressive positive relationship between Ni ard Cd in the phosphorite supported the affinity with iron in the Gangau- 3298 o. in J O 0 If) f<^ C E ex o Q. ^ iri Q> + o £ c a. 8 c Q: «• o CD s E99 Ferruginous Formations which form a distinct group of elements during oxidizing to reducing, marine and shallower conditions of the Proterozoic basin (Gulbrandsen, 1966 and Saigal and Banerjee, 1987)(Figure-89). VI»3>13^ Cd vs> Co s The negative correlation between Cd and Co indicated that due to more ionic radii of Co could not be replaced in the apatite crystal lattices. Cd might have got the site in the apatite or both the elements might have been adsorbed in the gangue minerals of the phosphorites (see Saigal and Banerjee, 1987) (Flgure-90}. VI,3a4. Cd vs, Cu : Cd and Cu show strongly positive relationship in the shale-phosphorite samples but they have weaker negative correla tion in the ironstones, quartz-breccia and secondary phosphorite samples. It may be possible that the both the trace elements were replaced in the apatite crystal lattice on a minor scale and the remaining contents were adsorbed by the crypto to micro- crystalline masses of phosphatic, ferruginous and clayey minerals. The iron-oxide and hydrated Iron-oxide may play an important role 300 + o u a: o OL UJ »— ct: cr X UJ O o K- a. cn fS <*^ 8 301 during highly oxidizing conditions of the basin (see Saigal and Banerjee, 1987) (Figure-91). VI.3,15. Co vs, Cr s Co and Cr show progressive positive relationship in the samples of phosphatic shales, quartz-breccia and remobilized rock types, but a weaker or random relationship exists in the ironstone- phosphorites. The geochemistry and other features of this relation ship is also similar to those of the trace elements discussed (Flgure-92). yX.4. CORRELATION BSTWEEN MAJOR AND TRACE METAL I0I9S : Most of the trace elements are related with the major elements directly or indirectly in the carbonate, silicate and phosphate bearing rocks. The presence or absence of certain trace metals in the rocks is much helpful and most significant to know the palaeo-climates and nature of deposition of the sediments in the area. In the present study an attempt has been made to ascertain the geochemical relationship between major and trace metal content in order to' assess the genesis of phosphate bearing rocks. 302 VI,4>1> P^O^ vs, U^OQ : In the study area, the ^2^5 ^^^ws strongly sympathetic correlation \^ith U^Og in all four types of phosphorite seniles. This relationship gives the following informations regarding Proterozoic phosphorites s- 1. The phosphorus system has a better chemical affinity + 2 with uranium in which divalent Ca followed by many divalent ions with U in the apatite crystal lattices. 2. This relationship indicated high oxidizing conditions due to absence of organic matter, microrganisms and pyrlte. 3. This indicated co-precipitation of phosphorus and uranium in the sedimentary environment in which the Eh and pH of the basinal waters were very close to each other for their precipitation (see Elliot, 1968; Nathan and Shlllonl, 1976; Viqar, 1981). 4. The deposition took place in the low lying and stable areas in which the influx of the clastic material was small in the shallower marine conditions (see Pettijohn, 1975). 5. The adsorption of uranium may be on the surfaces of apatitic, ferruginous and clayey minerals by diagenesis processes (see Goldschmidt, 1954; Jensen, 1958; Mason, 1966). o •o / 303 o o en (n > in O or I C + o • < a. (U LU *-* I— jQ o CX X u Q- -C (A E a: in C o o Ui ?- X o Q. X in • • cn -J O < o o < 01 U> — GJ ^ fN ro in u> ir» xj ro 04 • • or u. 304 6, The reduction of u"*" to u"^ may have taken place due to the presence of cryptocrystalline clay minerals (see Slansky, 1979)• 7, The uranium Is associated with phosphatic content and other gangue minerals by secondary enrichment processes and this may be related to minor unconformities or diastem in the area (see McKelvey and Nelson, 1950; Swanson, 1960)* 8. The occurrences of uraniferous phosphatic rocks in the ferruginated zone indicated the oxidizing conditions of the basin (see McKelvey,et al.# 1955; McKelvey and Carlswell, 1956). 9. The uranium might have leached and remobilized and reprecipitation by episodes of mild weathering in these areas (see Berzinia, et al., 1978; Starinsky, et al.# 1982) (Pigure-93). VI.4,2. P^Og vs, Ni : In the study area, Po^S ^^^^ positive relationship with Ni in primary phosphorites but a negative correlation in secondary phosphorite samples. In primary phosphorites the positive relationship may be due to minor adsorption of Ni by large bodies cryptocrystalline masses of iron, clay and' 305 + 0 O <] U Q: o UJ X UJ o. cn u o »— o h- X QL o tr in o X X o Q. if) o a. O o if) X X o CL UJ X U > GQ o UJ a: < >- N < a O < X U CL (T) if) — c3 tn '^ CO > "— C^* no -sT O Q:^ £ c 0) CL LO in c o JH CI I < • kC^ L 306 phosphatic materials. The phosphatizatlon took place during the deposition of •iron formations* with which Ni has close chemical affinity. On the other hand, a negative relationship among these two elements in secondary phosphorites may be due to leaching/weathering of the ores* due to which Ni concentra tion decreased and the phosphate contents increased (see Saraswat, et al*# 1967; Israili and Khan, 1978; Lucas, et al.# 1978; Saigal and Banerjee, 1987)(Pigure*94). VI.4.3. P^Qg V3> Pb s The P2^c shows random or negative correlation with Pb in all phosphorite samples. This relationship may be due +2 +2 to mutual divalent ionic substitution of Ca by Pb in the apatite lattices because ionic radii and charges of both are very close and similar (see Howard and Hough, 1979 and Proshlya- kova, et al., 1987) (Figure-95). VI.4.4. PpOg vs. Cr The P2O5 has a random or negative correlation with Cr in all phosphorite samples in the study area. The bright red colour of the phosphorites may be due to the presence of Cr203. This relationship supported the chemical affinity with o 307 O O vr in o o c E 0) CL o + o o UJ • ^ V— O -in JZ (Z en O c X o I— or 4^ LU ^ o £5 o ir» u X cu CL cr cr tn O Q. O o o CO X X X tn LO ir> O cr- xj n CM • > cn a. ^ o > o o X Q: o CL ? ^ L < Q- UJ or Q LU cr —I o UJ ffl < o O < ^ if)X i/t o o in — rs* f*^ vj- o o c QJ o in c o cu Q: I 308 V-Ni-Cr-Zn associations in the clay minerals• The mild weathering of ores might have redistributed within the sediments packages* The very high concentrations of iron and phosphate may entraped some Cr. On a minor scale Cr* might have been replaced hy P in the sedimentary basin at the time of diagenesis (see Minguzzi# 1941; Heinrich, 1954; Frahlick, 1960; prevot and Lucas, 1980 and Saigal and Banerjee, 1987} (Figure«>96} • VI>4,5. P^O^ V3> Cd s The Pn^^B s^o^'s positive as well as negative relationship with Cd in primary and also in secondary phosphorite• In the primary phosphorites the presence of Cd may be due to its adsorption by apatite, clay and iron bearing minerals. On the other hand, in case of secondary phosphorites the weak negative correlation between the two may be due to weathering of the ores in which the Cd metal might have been redistributed within the sediments groups or partly lost during diagenesis processes. The similar and/close ionic radii of Cd and Ca may help in ionic substitution in the apatite lattice (see Krauskopf, 1955; Gulbrandsen, 1966 and Saigal and Banerjee, 1987) (Pigure-97). 309 in O nc>t C E tc UJ o X UJ CL c — (/> o O O O X J5 U X X CL % Q- tn < o I, o o Ul CQ k N (n cc o — C3 O ^—< esta fr% ^S > in o -in o n or* c o e 01 -in a. fs 0) < O 0^ • • o • - LO IE tcn A o o/ - O J5 /o in I 1 1 I 1 en in m tn O ^ ro fN LO C3rcr- o 1 (V LL 310 VI.4,6, ^2^5 ^^* ^ • Like Cd, the Co also shows a more or less similar behaviour with ^2^5 ^" ^^^ four tj^pes of phosphorites in the study area. Co may be present on the crystal surfaces of apatite, clay and iron-bearing minerals during diagenesis of these sediiaents (see Saigal and Banerjee, 1987 and Banerjee and Saigal/ 1988) (Figure-98). VI.4.7. P2Q5 vs. Cu : ^2^5 ®*^^^^ positive correlation -with Cu in primary phosphorites and negative, in the secondary phosphorites. Cu might have been replaced on a minor scale by Ca in the apatite lattice or it may be presence as adsorptive element. This rela tionship also indicated a common source of Cu and ^2^5* ^^ ^^® other hand/ a negative relationship may be due to leaching/mild weathering of the ore in which the part of Cu might have been lost during diagenesis (see Cruft, 1966; Al-Bassam, et al.# 1983; Saigal and Banerjee, 1987; Singh and Subramanian, 1988) (Figure-99). O 311 ro Z) > o a o c Q; o o 00 O + o • < 3 a> LU cr o c U UJ X Q- cr. a: o X UJ o o CL a> 1— CL Q_ Q: X X Q: o o o < ft X X X U in tr» o 0- CL Q. u CM o 'C oin UJ I X >- UJ O • • o. Q: CD < o a LL *— M o UJ o in t— _J z z cr < o o < X oUJ tr 3 in if) a N *- r>i ro vf > o or E a. c c N cu c o Q: in in u> LH r>4 L 312 VI,4>8. PQO^ VS* V ^2^5 ^^^^^ ^ strong negative relationship with V in all phosphorite samples. This relationship supported the mutual +5 +5 pentavalent ionic substitution of P by V in the apatite lattices • The presence of V in the phosphorites may be due to chemical affinity with P^^c a^*^ adsorption by clay minerals (see Khudelozhkin, et al** 1972; Cook, 1972; Banerjee and Saigal, 1988)(Figure-100). VI,4,9. PQO^ VS. 2n s Like vanadium/ zinc also shows a negative correlation with P2*^5 i" aH types of phosphorites in the study area. This relationship may be due to mutual substitution in the apatite and/adsorption by clay and ferruginous content during and after phosphatization. The milt weathering was also responsible for a negative correlation of P2°5 ^^^^ 2n in which Zn might have been lost (see Prevot- and Lucas, 1980 and Proshlyakova* et al., 1987)(Flgure-101) VI.4.10. CaO vs, U^OQ J In the study area, CaO shows sympathetic relationship with U30g in all phosphorite samples. This relationship indicated L/1 CL ^ 313 in o m o e c 0) -r O in r4 •4-* a; in E o u CL c *— o o — X U u-» X tr a. •4-* Li Q_ t: if) o O in < O X Q: Q_ CL in o > cr X U CO I Q- < o t« UJ o_ M en tn II < u s < X UJ o > CO in tn in > fN ro O o a "" u E c a. o CL o ^ > o O, a> c o o 4-» fM J2 01 o cr 1 O • a <3 314 that phosphatization occurred under the marine conditions during +2 +4 which minor substitution of Ca by U was possible in the apatite structure. Tlie enrichment of uranium in these phospho rites may be due to absorption and adsorption on the mineral surfaces• The mutual ionic substitution of calcium by uranium may be due to their similar/close ionic charge and ionic radii Sec (Kajitani, 1968; Howard and Hough, 1979; Altschuler, 1980 and Banerjee, et al.r 1982)(Pigure-102). VI,4,11. CaO vs. V : In the study area* CaO shows a Strongly negative correlation with V in all types of phosphorite samples. This relationship may be due to mutual ionic substitution of P"*" +5 by V in the apatite structure before the precipitation of calc-phosphates during marine, shallower and high oxidization conditions of the Bijawar basin (see Howard and Hough, 1979) (Pigure-103). VI.4.12. CaO vs. Pb : CaO shows negative correlation with Pb in all types of phosphorites in the study area. This relationship may be due to +2 +2 ionic substitution of Ca by Pb in the apatite structures during high oxidizing conditions of the basin. The Pb may be 3 315 o tn > O a o E a; -f O O LU cr: o c X o UJ Ul a. ion Ui o o X 1— X X Q- en (T a. 0_ O in in o X o Q. X o o ino X X Q- UJ a. U L < m a o Ui in M o < < s or «/> tn — <3 fN m o a o c a; in c o -2 o o c3 316 due to adsorption by apatite on its crystal surfaces. The presence of Pb in the phosphorites may be due to natural analogue with CaO as obsejrved by earlier workers (see Kreidler and Hummel, 1970; Altschuler, 1980 and Pettijohn, 1984) (Figure-104)• VI,4.13« CaO vs. Ni : CaO shows a progressive positive correlation with Ni in almost all the phosphorite samples in the study area. This rela tionship may be due to leaching of the phosphorites by mild weathering, absorption and adsorption of Ni content by apatite, clay and iron-bearing minerals during and/after precipitation in the marine, and oxidizing conditions of the Proterozoic sedimentary basin (see Howard and Hough, 1979)(Figure-105)* VI.4.14. CaO vs, Cu t In the study area* CaO shows a linear and progressive positive relationship with Cu in all the phosphorite san5>les. Cu might have been absorbed in the early stage of phosphatiza- tion of apatite minerals in their structure and/later on adsorbed on the crystal surfaces of apatite and iron and clay bearing minerals during diagenesis processes of the primary ores (see Gulbrandsen, 1966; Saigal and Banerjee, 1987) (Figure-106). + o UJ cc Ui o i— X LiJ CL 1— tn o o X Q- X 111 Q_ O in X or o if) < o X CL oT O Q. u a Lu rr X a: LU GQ Q- < O2 o 1— N -J o to < u o < X LU nr 3 in {ft C5 '— r^ r^ 31S VI,4.15> CaO vs. Cd : In the study area, CaO shows a randomly negative correla tion vdth Cd in all phosphorite samples. This relationship may +2 +2 be possible by divalent substitution of Ca by Cd in the apatite lattices during primary and secondary stages of phos- phatization. This relationship is also indicated the similar crystallo-chemical favourability (see Altschuler, 1980 and Saigal and Banerjee, 1987) (Figure-107)• VI.4>16. CaO vs> Co s In the study area# the CaO shows a progressive positive relationship with Co in all phosphorite samples. This relationship indicated the adsorption of Co on the mineral surfaces of apatite and gangue minerals of phosphorites during diagenesis of the primary and secondary ores. The higher content of Co also may be due to chemical affinity with other elements like iron, nickel, copper, chromium, etc., which are already associated with these phosphatic sediments (see Saigal and Banerjee, 1987) (Pigure-.108). VI.4.17. CaO vs. Cr t In the study area, CaO shows a negative but random relationship with Cr in all phosphorites. This relationship O o 319 O c 0) •4— + Q • <1 u in o c Ui UI a. »— f- (/) g •4-* E ° JS cu CL cn < Or: o — Is X ^ o Si- a. cj UJ or UJ OQ o M •— fN (V> o o o c a> 4-» 0) tn c o JS r to cr-- in in o o a o L 320 may be possible due to minor substitution of P* by Cr^ in the apatite lattices. The random and scattered distribution of Cr values with CaO content may be due to lateritization of the ores during diagenesis processes (see Cruft, 1966) (Pigure-109). VI.4,18, AI2O3 vs> Co s In the study area, Al20^ shows a negative correlation with Co in all the phosphorite samples. This may be possible by mutual tonic substitution of Al by Co and/adsorption on the apatite lattice (see Saigal and Banerjee, 1987) (Pigure-110). VI,4,19, AI2O3 vs, U^OQ S The AI2O3 shows a negative correlation with U^O in the primary phosphorites and a random but progressive correlation in the secondary phosphorite samples of the study area. In early +2 stage of phosphatization it may be possible that the Ca might not have been substituted by Al in the apatite lattice, the collof>hane (calc-phosphate) apatitic phase were formed but on the other hand, in secondary phosphorites minor contents of Al* were introduced in the apatite phase in which the crandallite (calc- Al-phosphate) was formed in the voids/cavities randomly by episodes of chemical leaching and/weathering of primary phosphorites. The 00 O o 321 O ??. c ;? ^ CD / ! o a; / o + o 3 LU to I— Q- cr Ic o in X LU CL c H- in o o — o j5 Ui "^X ^ ^ ? 11 o a; X — D- Q_ cr 01 < ,^1 o *N o o 1 O^ X X S a in o ^ m o CL Q- o •«—\ cn a. o o >- u O X cr CL < Ui QQ UJ a O M < O oo u X uu <0 o cn {/) O -^ fN ro D 322 + o • < u t~~ Qo: UJ UJ CL 01 or O o o X LU X CL ^ CL X CE: en If)o o o X o X X CL u CL CL LU U) >- Ui a: o < CD X o OL o u o < u LU CD in i>i < ro X '— rsi P-) ^ o(N l o c I CD c o J. 323 enrichment of U3O particularly, in the secondary phosphorites were found as dark coloured thin veinlets of crandallite with fine coatings (see Pric and Rose, 1981) (Figure-Ill), VI>4,20> MnO vs> U^OQ S In the study afea, Mno shows both types of similar relationship as AI2O3 with U3OQ in all phosphorite samples. This relationship further supported the above observations in all four types of phosphatic sediments (see Pric and Rose, 1981) (Figure-112). VI.4.21. CX>2 vs. U^OQ The CO^ shows negative correlation with U^Og content in all phosphorite seniles. This relationship indicated the loss of CO2 from carbonate-fluorapatite by leaching/weathering of primary ores by groundwater and sea-basinal tides and waves resulting the precipitation of U^OQ in these sediments. The alkaline nature of basinal water also helped in the precipitation of uranium in these phosphatic sediments in the area (see Tugarinov, 1975) (Figure-113) 324 VI«4.22. H^O'*' vs. U-^QQ : Generally* water plays a very significant and most active role in the foEaatlon of apatite with or without uranium in the phosphatic rocks in the different deposits. In the study area* the H2O shows a progressive negative relationship with tJ-Og like CO2 in all phosphorite samples. The more water will take more uranium into solution and on the other hand the decreasing content of H^O* will favour the precipitation of uranium in the phosphatic sediments,. This relationship also indicated the marine, shallower, humid to arid climatic conditions of the area during Proterozoic time (see Bet*khtin, 1959) (Pigure-114). VI,4.23, gen03 vs. U^OQ t In the study area* ^®2^3 ®^^*^ ^ strong negative correla tion with VJ^OQ in all phosphorite samples. This relationship indicated the high oxidation-reduction conditions of the Bijawar basin which is free from the iron-sulphide minerals (pyrite, etc.) absent. The U^Og content might have been brought by iron-oxides and later on fixed on the minerals surfaces of gangue minerals, cellophane, crandallite, etc. The U^Og content is slightly higher in secondary phosphorites in which cellophane altered into cran dallite which is also enriched in ferruginous minerals. Thus, it may be possible that iron-oxide and phosphate may be the carriers o (^32ir en ^ ro o CN o c £ o ex o o + o • < -0 LJ (A I— C o o o LU X JS Q, a; Q: U) o O UJ Xo X H- CL X CL ir cn O < o o X O L aX. XCL if) a. o o X >- aUJ: < UJ m Ui 2a: 3" _i 0 < 0 X LU U) in o ^ rsi n c en c J. 32G o E Q. C + o • LU x: Q: I/) o c Ui Ui Q- o >— K- iXn cc o o Eo iS 1— X X QX_ or CL c o (/) t/> < X O oo Q- o X o t/) X a. O QUi: X > UJ m Q- D: z < o N U a ^— \— _I oz in a: < u 2 < X UJ Qo: 3 en in CJ 8 ^ •- fM ro m (N 0) Li- E c a. o O C o cu O) 327 of uranium In which the remoblllzatlon and reprecipitation process took place at the time of high rainfall to arid climatic conditions (see Alder, 1970 and Blrzlnia, et al., 1978) (Figure-115). VI,4,24, ge^O^ vs> Cr x The iron shows progressive positive relationship with Cr in all samples of phosphorites in the study area. It may possible that the part of Pe"* has been replaced by Cr in the basinal sea environment in *^ich high oxidizing conditions, prevailed « and later on, the cr"*" concentration was fixed on the clay and iron-bearing minerals at the time of precipitation of phosphates in the area. The reroobilization and reprecipitation of the primary ores may also increased the Cr content in these sediments (see Bliskovskiy, 1969 and Proshlayakova, et al., 1987) (Figure-116). VI,4.25, ^^2^ "^^^ ^^ ' •^^2^3 ^^^^® ^ progressive positive relationship with Co in all samples of phosphorites in the study area. This relation ship suggested adsorption of Co by the cryptocrystalline masses of hematite-magnetite, goethite, iron-oxides and ferruginous cement and clay minerals during primary and secondary stages of phosphatization in the marine, shallower parts of the basin (Figure-117). 32B + O O < UJ o LU UJ X a. ^— 01 a: CE: o o o X ui X X Q_ •— Q_ a. cc t/) tn o O o < X X X o Q_ a. Q- o in u o >- a: X Q: LJ m Q- < o o »— M 03 UJ z to H- -J o cr: < o o < ro X u ct: 3 tn (n — C3 :5 *— CM ^ m o GO c o CD a. U) c o cu cj- Ix. 329 VI>4>26, Fe^O^ vs, Ni : In the study area# like Co, P®2^3 ^^^^^ ® progressive positive relationship with Ni in all the phosphorite samples• Ni concentration may be high due to leaching and weathering of the soft gangue minerals* It may be possible that Ni follows the elemental group system in which Pe-Cd-Co-2n are abundant. This relationship is an indication of humid to arid climate and shallower^marine conditions of the sedimentary basin (see Berbeck, et al., 1981 and Saigal and Banerjee, 1987) (Figure-118) VI,4*27. Na20 vs. U^OQ t In the study area# Na2^ shows progressive positive rela tionship with U3OQ in all phosphorite samples. This relationship supported the alkaline nature of the basinal sea-waters at the time of precipitation of phosphorites which helped the phospha- tization process (Flgure-'119) . VI.4.28. K^O V3> U3OQ s Like Na20/ K2O also shows progressive positive relation ship with U^Og in the primary phosphorite samples in this area. On the other hand, there is a weak negative relationship between the constituents in the secondary phosphorite samples. A progressive +2 +1 relationship indicated partial substitution of Ca by K in the <^ 330 > fv c £ o. ex -(- O • < u in a. cc Ic o m LU X c »— o ^— to or o Hi o o5 X JS ^— X X CL CL CL or cn tn o o o < X X X O -r—* CL CL Q- O I if) • • >- LU Q: 2? o GO X a: Li Q. < o Q »— M LU z {/) »— 'Z, cr ce o o < O Uui or ID LO o o =r ^ r»4 n > (M o o o o a ID CO o o (A C o *- O j3 (/) 331 apatite lattice and also the higher alkaline conditions of the basin during phosphatization. In secondary phosphorites, the K2O content might have lost during weathering (see Howard and Hough, ^ 1979) {Figure-120). VI,4,29• SlO^ vs. U^OQ S In the study area, SiO^ shows strong negative correlation with U^Og in the phosphorites. This relationship indicated that the SiO^ might have been replaced by' PO^ during the early stages of phosphatization in which the UO. was also replaced in the apatite lattices. In the secondary phosphorites the SlO* might have been weathered by groundwater and sea-waves action in which the tJ^O- content increased slowly. The remobilized uranium might have reprecipitated at a suitable pH and Eh of the waters. The part of the U^Og content may be present as sorption by gangue minerals (see Pric and Rose, 1981) (Figure.121). VI.4.30, SIO^ vs. Cr J Like U^Og , the SiO^ also shows a negative relationship with Cr in all phosphorite samples In the study area. During phosphatization, SiO^ might have been replaced and/leached by chemical weathering before and/after the precipitation of phos phorites. In this way, SiO^ decreased and the Cr content increased o o 33^ O o 2 o o (7) r-O a£. CL c o CD o + O • < o LU o a: / 0 I c X /• o LlJ us a. H- in cr 0 —o o X u X 5o IX t— Q- a. / oA or cr tn in o o o < X X X 0 &n in in o •- Ln o a. Q. CL u in LlJ r4 cm o > UJ m o X 2 < o V— M LU o in (X. —I o 2: < o 0 < X UJ a: Z) in tn C3 *- E c Q. CD "- 0) > * (D cn c o iS 01 IT 333 slowly in these phosphorites. These trace metals were adsorbed by the gangue mineral surfaces (see Howard and Hough, 1973) (Pigure-122). VI.4.31. SlO^ vs. V s Like araniom and chromiuun, Si02 also shows a negative correlation with vanadium in all phos^ihorite samples. The removal of SiO^ by PO, within the besin might have responsible for increasing the concentrations of vanadium during high oxidizing marine conditions of the Bijawar basin. Vanadium might have replaced p during primary and secondary phosphatization processes Like other trace elements vanadium might have been present in the fine grained gangue constituents of the phosphorites (Figure-123)• VI.4.32. SiO^ vs. Ni t Si02 also shows similar negative correlation with Ni as with uranium, chromium and vanadium in all phosphorite san^les in the study area. This relationship indicated that the Ni also followed the same trend like other trace elements during the time of phosphatization of phosphatic rocks in the Bijawar basin (Pigure-124). 33^ Ul NJ ^ en in > Q m X S > N O mr- > 'V CD Xi m -< X m o o o X X O o to o "0 -0 m o X o O 5 T) m —H X m o m I> « o 4- 33ff VI.4>33, MgO vs, Nl : In the study area, MgO shows a negative correlation trend with respect to Ni in all the phosphorite saxiples. The phosphorites of the Hirapur area belong to siliceous, arenaceous and ferruginous groups and the above relationship supported these groups. The positive trend in the Mussoorie and Pithoragarh phosphorites may be due to the calcareous nature of the phospho- +2 +3 rites. It may be possible that Mg were replaced by Ni before the precipitation and the diagenesis of phosphorites within the basin. On the other hand a part of Mg might have been replaced +2 +3 by Ca in the apatite lattices and Ni were adsorbed by the fine grained clay and iron bearing minerals (see Saraswat, et al., 1967; Santosh, 1988)(Pigure-125). VI.4.34. MgO vs. Cr s Like nickel, MgO shows a progressive negative relation* ship with CrjOj in all phosphorite samples in the study area. It may be possible that Cr might have followed a trend similar to nickel during phosphatization of the phosphatic sediments (see Santosh, 1988) (Figure-126). J^ Lfl. ^336 O o 3 O o o UJ UJ X tr a: o UJ o o X I— X X Q- a,«— Q- Q. o o o < X X X O Q. a. Q- o l/> UJ O or UJ X DC z. CD < o O I— M lii z —I 7L ^ o o < X< UJ ct z> t/) V) IT C3 ^ CM 1 r 1 1 r 1 1 1 1 00 o CD 00 o CM o w ^ *j vT ro r^i fN 04 r^ O o c o CD O o o o CD o O a o o o o p o O o o o 8 p o o o o O o o o o o O O o a: O or* *0 • • m VI,4>35> Ratio ^300/^2^5-^-^ PaQ m the study area« ^3^B^2^5 ^^^^^^ varies from 0.0002 to 0.0045 in shale phosphorites; 0.0025 to 0.0032 in secondary phosphorites; 0.0018 to 0.0023 in ironstones phosphorites and 0.0002 to 0.0036 in quartz-breccia phosphorite sarr5»les. The ratio values of ^S^Q/PO^S ^^^^ ^ progressive positive correlation with p^O- content in all types of phosphorite samples as shown earlier between U^OQ and ^o^S* ^^^^ relationship indicates the following - i) phosphatization took place during marine conditions;, ii) Oxi dizing state basinal waters; iii) leaching of ores by mild weathering; iv) constant ratios values supported the hurried conditions; v) enrichment may be due to episodes of remobilization and reprecipitation of the primary ores at places toy groundwater rt-ction; and vi) open sedimentary environment deposition which took place during ancient period (early Proterozoic) (see Altschular, et al#, 1958; Burnett and Goihberg, 1977; Cullen, 1978; Force, et al., 1978; Al-Bassam, et al.# 1983) (Pigare-127 and Table-XII). VI.4.36. Ratio ^3Qe/Fe2^3 ^^* ^^2^3 * In the study area, the ratio values of U^O^Fe^O. varies from 0.0003 to 0.0106 in shale phosphorites; 0.0058 to 0.1232 in secondary phosphorites; 0.0031 to 0,0069 in ironstone phosphorites and 0.0002 to 0.0140 in quartz-breccia phosphorites san^^les 338 respectively* The ratios of ^2^e^^^2^2 show a random to linear relationship in the primary and negative relationship in the secondary phosphorite san^les» The deposit is free from sulphide mineralization and its geochemical features also differ from above Nakatsugo deposits' of Japan. Thus# the geochemical behaviour of these elements differ in both the deposits. The phosphatization took place in the Bijawar basin after precipitation of iron- bearing minerals like hematite, magnetite, limonite, etc. The goethic and iron-oxide coatings are the secondary features which took place at the time of diagenesis processes (see Kajitanl, 1968) (Figure-128 and Table-XII). VI.4.37. Ratios ^2^Q/^^2^2 ^^' ^2^5^^^2^3 * In the study area, the ratio values of ^2^Q/^^2^3 varies from 0.0003 to 0.0106 in shale-phosphorites; 0.0058 to 0.1232 in secondary phosphorites; 0.0031 to 0.0069 in ironstone phosphorites and 0,0002 to 0.0140 in quartz-breccia phosphorites. On the other hand, the ratio values of P2^5/^®2S ^a^i®^ from 1.33 to 2.54 in shale phosphorites; 2.27 to 38.24 in secondary phosphorites; 1,66 to 3.07 in ironstone phosphorites and 1.09 to 3.86 in quartz- breccia phosphorites. These ratios show a progressive positive relationship each other in all four types of phosphorite samples. This relationship regarding genesis of phosphorites as phospha- tization took place during iron formations of Proterozoic period 33S or* + o * < UJ o UJ X LU Q. o UJ X t= CL cc w in < o ° 5 X a. oi o ^ m X Q- P ^4 UJ < X v> v^ 5 § ^ IN m -si- -2 O :5^ 3^0 in the high oxidizing conditions. The high oxidizing conditions of the basin are responsible for jremobilization and reprecipita- tion of the ores. This also indicates the adsorption of PjO^ content by iron particularly in secondary phosphorites samples in the marine environment. The paft of the uranium and P2^s ^^^^ adsorbed by clay bearing minerals besides iron and detrital quartz (see Nriagu, 1972; Bortleson and Predlee, 1974 and Subramanian, 1976) {Figure-129 and Table-XIl). VI.4.38, Ratio V/PQO^ VS. P^t?^ s In the study area, the ra^io values of V/P20^ varies from 5.4445 to 10.1474 in shale phosphorites, negligible to 0.6375 in secondary phosphorites; 0.5771 to 3.7462 in ironstone phosphorites and 0.5042 to 5.7597 in quartz-breccia phosphorites. These ratio values qf V/P^Oc show a negative relationship with the content of ^2^ ^" ^^^ four types of phosphorites in the Hirapur-Mardeora areas. This relationship indicated the mutual ionxc substitutipn of P"^ by v"^ in the apatite lattices during similar physical chemical conditions of the marine Bijawar basin (Israilx and Khan,. 1980) (Figure-130 and TablerXIl). VI.4.39. Ratio Cu/£>^0^ vs. P^O- s In Hirapur-Mardeora areas# the ratios of CuA^o^c varies from negligible to 4.5315, 9.1900/ 7.3874 and 12.0757 in the 341 O + o • < u UJ t: a. UJ O t- X o i^ r- 1 o O o tx in '^ £ r** fM CM ion "- UJ a. QC 2 CO < O O Nl UJ 5 t— ^ ^ Q -J ^ tn or in or* < 8 CD < o U~l o »— fM rn sj o - in m o 0 O 55 o + rsi cu _ m •-• cu J3 _ o Q- JC - m (n c o 1 1 1 1 1 < 1 1 1 1 1 I Q a^— a> o o o cp O o o o o o o ^ o <0 rst P o VI.4.40. Ratio Cr/AloQ3 vs> AI2Q3 - In the study area# the ratio values of Cr/Al20n varies from negligible to 42.1568, 194.8051, 285.7142 and 215.44 in the samples of phosphorites of shales, secondary, ironstones and quartz-breccia. Like other elements ratios, the Cr/Al20- ratio values show a nega tive behaviour with respect to AI2O2 (by weight per cent) in all four types of phosphorites in this area* This relationship further supported mutual ionic substitution of Ca+ 2 by Al+ 3 in the apatite striacture by which the crandallites coatings were formed during the diagenesis of secondary phosphorites. A part of the Cr"*" might have also been replaced by Al"*" during high oxidizing, marine, shallower conditions of the basin. Chromium and aluminium were also fixed on the surfaces of clay and iron-bearing minerals (see Prevot and Lucas, 1980 and Banerjee, et al., 1984). (Figure-132 and Table-XIl). 343 SUMMARY : The distributions and inter-relationships of trace elements namely, U, V, Ni/ Cu, Co, Zn, Cd, Ga* Pb and their correlations with major oxides in the primary and secondary phosphorites revealed that these elements were precipitated by direct, inorganic, syngenetic and authigenetic processes in the primary ores. On the other hand, epigenetic,weathering,, remobilization and reprecipitatlon in the voids and cavities fillings in the secondary ores. The phosphatization was taken place in the fairly oxidizing to slightly reducing environment, tropical to arid climate, saline sea-basinal waters, shallow, marine, epicontinental sea shoals, continental margin in the Bijawar basin. Most of the above trace elements are the result of absorption, adsorption and partly replacement out and Inside the apatite lattices. The random distributions and poor correla tions among the constitutents may be due to mild leaching of the ores. 344 CHAPTER - VII CLASSIFICATION OP PHOSPHATIC SEDIMENTS VII>1, GENERAL STATEMENT S The term •phosphorite* has been used for those sediments in which a phosphate minerals are the principal constituents, other terms such as rock-phosphate, bedded phosphate and the like have also been applied to these rocks. Residual phosphate is a term applied to an accumulation of insoluble phosphatic materials left as a residual deposit (Pettijohn, 1975)• Rocks may be classified according to schemes that are primarily either genetic or descriptive. The primary objective of a genetic classification scheme.is to group rocks according to similarity in origin. A descriptive scheme, however, does not necessarily imply to their mode of formatipn, its primary objective is to categorise rocks with respect to their texture and composition. Compositional classification may be either chemical or mineralogical. Chemical composition, particularly with respect to grade of P^^c content has been used most extensively by mining engineers and mineral dressers to describe the phosphate ores. The phosphate ores have also been characterised as to chemical composition by the term 'Ferruginous*, 'silicious•, and •carbonaceous' (Israili, 1978). }|5 Phosphorites in the current literature of the world over have vaguely been defined without any specific chemical and/mineralogical parameters • For exannple the phosphate rocks having a wide range of IO96 to 50^6 ^2^5 ^^^® been classed in the same category (Riggs# 1979). Such a grouping creates confusion for user industries, in planning and proper exploration/ exploitation of the deposits. Phosphorite commonly termed as phosphatic rocks or rock phosphate, is of sedimentary origin. Apatite is the common phosphate mineral of marine origin (Gulbrandsen, 1969; Bentor, 1980). The Proterozoic phosphorite deposits are distributed and both in the Extra-Peninsular region^in the Peninsular Shield areas of Central* Western and Southern India. The significant occurrences are - (i) Jhamarkotra and Matoon in the Aravalli Supergroup of Rajasthan, (ii) Jhabua in the Aravalli rocks of M»P., (iii) Hirapur-Mardeora in the Bijawar Supergroup of M.P., (iv) Chelima-Pachcherla in the Cuddapah Supergroup in Kurnool district (A.P.) and (v) Pithoragarh in Gangolihat Dolomite Formation and Mussoorie deposits of Inner Kumaon Himalaya of U.P. (Nath, 1984 and Saigal and Banerjee, 1987)• VII.2. CLASSIFICATION OF PHOSPHATIC SEDIMENTS OF THE STUDY AREA t Many earlier workers had proposed several classifications of phosphorites of India and other countries of the world on the 346 basis of geologic age, stratigraphic columns, textures, mineralogy* genesis, presence and absence of associated matrix* derivatives from different types of country rocks (Igneous, sedimentary and Metamorphic), environment, grades of phosphatic ores and chemical composition. The bases of classifications are - (1) There are three types of phosphate rock, namely, sedimentary phosphorites of marine origin, apatite-bearing t alkaline igneous complexes and phosphorites of guano origin. Of these the sedimentary phosphorites have historically dominated • the world production scene. At the same time the igneous complexes, have beeh gaining and the guano origin deposits diminishing in inportance in the last two decades (Howard, 1979). The Bljawar phosphorites of Hirapur-Mardeora area are classified with the sedimentary phosphorites of marine and shallower water origin. (2) Sedimentary phosphorites are initially authigenic minerals which form on the sea floor (Riggs, 1979). Studies of carbonate sediments by Folk (1959* 1962 and 1968) and others have shown that complexity of carbonate rocks can be greatly simplified by considering two broad classes of sedimentary particles, viz., 1) orthochemical (orthochems) and 2) allochemical (allochems). Ortho-chemical constitutents are non-clastic and clay-sized sediments formed physlcochemically or biochemically within the area of deposition and show little or no evidence of 347 transportation or aggregation into more complex entities (Folk, 1968). Allochemical grains are larger than clay-sized, clastic sediments that have formed physiochemically or bio chemically within the area of deposition but which are organised into discrete aggregated bodies and have for the most part suffered same transportation within the area of deposition (Polk, 1962), The description of phosphorite sediments can be approached similarly since they are also composed of ortho- chemical and allochemical components. Riggs (1979) recognised that under certain circumstances, the primary phosphorites are modified by secondary processes. Thus, he described two additional broad classes of sedimentary particles which are often important and essential in unraveling the complex phosphate sediments system-lithochemical (lithochem) and metachemical (metachem). The term lithochemical was introduced to describe older clastic rock fragments of similar composition formed physico-chemically or biochemically during a prior geologic ages and which were initially deposited and lithified beyond their present site of deposition. Thus, any or all of the other classes of phosphorite sediments which have been later eroded, transported and redeposited as lithified grains in a significantly different and younger sequence of sediments are included in this class of sediments. 348 In the study area, on the basis of above, the shales and ironstones-phosphorites classified into authigenic and orthochemical in which the grain sizes are clay to silt sized which do not show any transportation. They were originated by physico-chemical processes within the basin. On the other hand, the quartz-brecciated phosphorites are allochemical and composed of angular to sub-rounded grains of quartz. These allochems are larger in size than that of orthochems. The shales, ironstones and quartz-brecciated phosphorites are basically primary in origin and at places, due to mild weathering of the primary shale-phosphorites some secondary phosphorites are formed. The phosphorites that have associations of some slates and phyllites showing low grade metamorphism, have been grouped with the metachemicals• (3) Phosphates occur in both sedimentary and igneous rocks. Emigh (1958) has proposed a genetic scheme for classifying the sedimentary phosphates. In the Permian Western phosphates, he recognizes, phosphates that are 'in place* and those that are •residual'. Residual types are defined as those that have been concentrated in situ by the weathering process. *In place' phosphates are those occurring as originally deposited. Emigh (1958) defines another category called altered phosphates, which applies to original carbonate-fluorapatite that has been converted partially or wholly into aluminium-phosphate (e.g. wavellite). ?49 He al30 Introduced another category of redeposited phosphates, which applies to phosphates that are redeposited in the form of phosphatiaed rocks. According to him redeposited phosphates are believed to be composed of francolite (that is carbonate- fluorapatite)• In the study area* all four types of phosphorites are bedded through the ironstones and quartz-brecciated phosphorites are nodular also. The first three phosphorites are of primary origin and the shale-phosphorites that were affected by leaching and/mild weathering gave rise to residual (secondary) type phosphorites. (4) Following is the conunercial classification of phosphorites based on P^^S content adopted and followed by mining engineers and mineral dressers in U.S.A* P^Oc content Ores iR per cent i. Acid-grade (high grade) 31.0 and above ii. Furnace-grade (intermediate grade) 24.0-31.0 iii. Beneficiation-grade (marginal grade)18.0 - 24.0 iv. Mill-grade (low grade) 10.0 - 18.0 V. Waste-shale (lowest grade) 10.0 Phosphate ores have also been designated as •Ferruginous*, •siliceous* and "carbonaceous*, depending on their predominant gangue associations. The P20^ (weight per cent) in phosphorites 350 that vary from 32,10 to 42.83% in secondary phosphorite falls in 'Acid grade*; 25.99 to 29.70% in ironstone phosphorites to 'Furnace gcade'; 14.79 to 25.05% in shale and 15.32 to 28.30% in quart2-breccia phosphorites belong to ^Beneficiation grade* (Table-Ill, A). On the basis of their dominant gangue ingredients, the shales, secondary and quartz-brecciated phosphorites aay be called 'siliceous' and the ironstones-phosphorites, 'Terruginous' (5) Rocks containing more than 19.5% P20g are defined as phosphorites, if they contain more than 7.8% ^2^5' -^^ s^® described as phosphatic (Cressmen and Swanson, 1964; 3ashinslcy, 1969; Parker and Siesser, 1972; Riggs, 1978 and 1979? Hath, 1984 and A^rawal and Subramaniun, 1986). Petti John (1967) proposed a classification of phosphate bearing rocks on the basis of variations in the P2O5 content into the following three categories - i. Phosphatized rocks ... 3 to 9.8% P^O, ii. Phosphatic rocks ... 9.8 to 19.5% ?20c iii. Phosphorite rocks ... 19.5 to 32.5% P^O and above. In the study area, on the basis of P^O^ weight per cent concentrations, the all four types of phosphorite sasples that contain more than 14.79% ^2^5 ^^^ ^ called 'phosphorites•. 351 (6) Kuenen (1950) suggested that ratios of CaO/MgO in the geological past show systematic drop prior to the Cretaceoas period. Vinogradov, et al. (1952) and Cf^ilinger (1956) and Chilinger and Bissel (1967) reported that the mean ratio cf CaO/MgO in Cretaceous was 56# about 10 in the mild-Palaeozoic, and only 4 in the Precambrian. Swaminathan/ et al. (1956) and Venkova# Rao, et al- (1957) reported the age of the Birmania phosphorite deposits as Palaeozoic on the basis of CaO/MgO ratio. Frolova (1959) also proposed a classificazion of phosphate bearing carbonate rocks on the basis of CaO/^gO ratio. RODDV and Korzina (i960), classified the phosphate bearing rocks on the CaO/MgO ratios and indicated that the increasing values of CaO/MgO suggested the decreasing age of the rocks. Sheldon (1966) also classified the Birmania Phosphorites on the basis of CaO/MgO ratios and later followed by Srikantan, et al. C1970); Madhava Rao (1972) and Viqar (1981). In the study area, the CaO/MgO ratio values varies from 25.32 to 119.05 in shale-phosphorites; negligible to 215.00 in secondary-phosphorites; 22.50 to 357.66 in ironstone- phosphorites and 19.51 to 93.12 in quartz-breccia-phosphorites. The ratio values indicated that as the age of phosphorites nore than CaO/MgO ratios are also increasing in all types of phos phorites. The Hirapur-Mardeora phosphorites belong to argilla ceous, siliceous, and ferruginous cc»nposition, thus the values 352 of Ca/MgO ratio are different from carbonate rocks as suggested by earlier workers in different deposits (Table-Xl). (7) Mollazal (1961) utilized the compositional parameters for the classification of phosphorite rocks. Elwakeel and Riley (1961) proposed a classification of phosphate bearing calcareous sediments on the basis of Na2 0/K20 ratios and also noted that these ratios are higher in calcareous rocks. In the study area* the Na20/K20 ratios varies froei negligible to 2.00 in shale-phosphorites; 0*53 to 1.71 in secondary-phosphorites; negligibre to 1.14 tin ironstone- phosphorites and 0,10 to 0,42 in quartz-breccia-phosphorites. The ¥ia2^/'^2^ ratios in shales and secondary -phosphorites are higher than those in ironstones and quartz-breccia phosphorites. Thus the phosphatic rocks are clearly divisible into two groups on the basis of their higher or lower Vla2^/^2^ ratios (Table-Xl) (8) Israili (1978) proposed a classification on the basis of recalculated 100 weight percentages of Si02# CaO + MgO and ^2^5 ^^^^ five groups mainly limestone/siliconite (100 s 1 to 50 : 1); slightly phosphatized limestone/siliconite (49.99 : 1 to 10 J 1); phosphatic-limestone/siliconite (9.99 : 1 to 2 t 1); calc-phosphorite/silico-phosphorite (1.00 si) and phosphorite (0.99 : 1 to 0^5 : 1). 353 + o C o Q. ^ + O c I ;2 O 5(/) O en si E a. o CU CI) a. $ 00 LU (T D CD 354 On the basis of above observations by Israili (1978), the recalculated 100 weight percentages values of SlO^, CaO + MgO and P2^5 ^^ all the fouj? types of phosphorites were plotted on the triangular coordinate paper. The recalculated weight per centages values of Si02# CaO + MgO and Po^q of shales, ironstones and quartz-breccia phosphorites fall in the •Phosphatic- silicanite' group barring two sanples of shale-phosphorites. On the other hand, the secondary-phosphorite samples with low SiO^ values fall in the •phosphatic-dolomitic-liroestone* group. Thus the primary and secondary phosphorites belong to tuw different groups (Pigure-133and Table-XIIl). SUMMARY : The Hirapur-phosphorites are classified on the basis of j- Origin as * sedimentary*, marine, shallower water deposi tion. Sedimentary processes as *authigenic* and *orthochemicals* are shales, ironstones ajid quartz-brecciated as 'ailo- chemical* and secondary as *metachemical'. Alternation as ironstones and quartz-breccia are 'non- altered' but shales as 'altered'/'residual* types gave rise to leached/remobilized type. 355 4. Coromerclal grade as secondary - 'acid-grade', ironstone- 'furnace grade', shale and quartz-breccia as 'beneficia- tion grade•, 5. Presence of PpOg content, all four types belong to •phosphorite* category. 6. CaO/MgO ratios as 'ancient' time. 7- NapQ/KnQ ratios, shales and secondary phosphorites are •highly alkaline* and ironstones and quartz-breccia are'moderately alkaline'. 8. SiQ2* CaO ^^ MgO and P^^S ®^ primary phosphorites belong to 'phosphatic silicanite* and secondary to the 'phos- phatic-dolomitic-limestone' g roups• 356 CHAPTER - VIJI PR0V2NANCE OF PHOSPHATIC SEDIMENTS VIII,1. GENERAL STATEMENT s Rivers of the world carry about 20 billion tonnes of sediments annually to the world oceans* Another 5 billion tonnes goes as dissolved load (Summerhayes, et al., 1976; Gibbs, 1980). Most of the bese-metal deposits of the world attributed to hydrothermal processes, where solutions of igneous derivations are deposited as cavity fillings and metasomatic replacements. Besides, these hydrothermal processes, the sedimentary process is also one of the major sources of such mineral deposits. It is well known that most of the sedimentary mineral deposits are formed in marine areas, mainly under shallow water conditions. These sedimentary mineral deposits derive their materials from the weathering of the rocks. These minerals are transported by means of rivers into the sea, where they remain in suspension as long as tbe solution does not undergo any appreciable change, either physical or chemical (Verma, 1980). Most recent estimates indicate that the rivers also carry annually 13.5 billion tonnes of sediment (Milliman and Meade, 1983) and 3.2 billion tonnes of dissolved solids (Meybeck, 1979), 357 There are, of course, other agencies of material transport such as wind, precipitation, volcanic activity etc., but rivers with a total of 16.7 billion tonnes of various elements in dissolved and solid forms account for nearly 90% of all global mass transport to the ocean (Garrels and Madaenzie, 1971; Subramanian, 1987). VIII.2. SOURCES OF PHOSPHORUS : Here, the author is going to discuss the various sources of phosphorus associated with the host rocks of Bijawar rocks group in the Bijawar basin. (i) Average dissolved phosphorus in the world rivers is about 0.05 ppm (Martin and Menback, 1980). The phosphorus in river sediments range from 700 to 1200 ppm (Subramanian, 1984). Turekian (1972 and 1973) gives a smaller range of phosphorus concentration in various sedimentary rock types and a crustal average of about 1000 ppm. According to Gibbs (1980), phos phorus can be used to calculate continental flux. Generally, the input of dissolved phosphorus by rivers into the ocean is estimated at about 1.7 x 101 2 gm/yrs, whereas individual estimates range from 0.4 - 2.0 x 101 2 gm/yr (Emery, et al., 1955; Stumm, 1973; Lerman, et al., 1975; Pierrou, 1976). 358 Input from the total atmosphere (Graham and Duce, 1979) Is about 1.4 X 10^^ gnv/yr.P Including about 0.05 x 10 gm/yr.P of anthropogenic origin. Most of this, air-borne P is, however, insoluble in ocean water; the input of P from the atmosphere 12 into the ocean is estimated at only 0*22 x 10 gm/yr.P. 12 Simultaneously, the ocean contributes about 0,33 x 10 . gm/ yr»P. to the atmosphere causing an yearly net loss to the ocean of 0.11 x 10^^ gm of P i.e. almost 10% of the annual rivers irqput. Another possiDle source of P is subsaacitve hydro- thermal activity, from which although no good data are available, is generally thought to be small (Bentor, 1980). The P-content of marine clays (700 ppra) is very nearly the same as that of clays carried by rivers and thus does not affect the balance of dissolved P. The P-content of marine carbonates is only 400 ppm (McKelvey, 1973; Garrels, et al.* 1975) but in view of the large amount of carbonate precipitation in the present ocean, this accounts for more than 30% of all P removed from ocean (News and Notes, 1959). River water flowing over the pre-existing apatite bearing granites has been considered to be the chief source of phosphate ions and the associated mineral constituents (Youssef, 1965; Khan, et al., 1981). Solubility of all phosphate minerals are very low (Atlas, 1979 and Subramanian, 1980). Calculations based on observed concentrations of calcium. 359 phosphorus, flaorine and measured pH and alkanity indicate that river waters in India, Including the estuarine water bodies are supersaturated with respect to'fluorapatite, hydroxylapatite and pure apatite (subramariian, 1980)• Estuaries, fiords and other near-shore basins commonly contain 1-10 mg atoms/m of dissolved inorganic phosphorus (Pevear, 1966) • Gibson (1968) presented evidence of a cold counter currents to the Gulf stream ccMning down along the eastern U.S. coast from the north at the time of the deposition of the phosphorite (Cathcart, 1968,a and White, 1984). It is a well known fact that rivers are the main carriers of phosphorus and its associated other elements in most of the phosphorite deposits of the world. Thus, in the study area there might be a river during Proterozoic period which brought the phosphorus from the underlying basement rocks of Archaean age towards the Bijawar basin. (ii) Phosphorus is a basic nutrient element whose concentra tions in sea-water are not constant with respect to the major conservative constituents such as Na and CI. The concentration of P in sea-water averages 2.3 mg atoms P/1 (0.071 ppm) (Redfield, 1958 and Pettijohn, 1969). The concentration ranges from essentially none in some surface waters to 12 mg atoms P/1 (0.372 ^^m) in the region of the Andaman Islands in the Bay of Bengal (Hart and Curry, 1960; Mostert, 1966; DeDecker, 1970^a,b; 360 Calvert and Price, 1971; Gulbrandsen and Roberson, 1973; Spencer, 1975 and Orren and Eagle, 1978). In most area», the warm surface waters of the ocean, contain only 0.0033 ppm P or even less, whereas deep cold waters.contain nearly ,0.1 ppm (McKelvey, 1973). It is mainly as inorganic orthophosphate ions, the dominant mode of phosphorus occurrence in sea-water. Gulbrandsen and Roberson (1973) have shown that beginning with the lowest concentration of P at the ocean water surface it rapidly increases to a maximum value that occurs at a depth of about 1,000 metres with ohly a small and variable decrease with continued increasing depth. Oceanic upwellings are thought to be one of the, major mechanisms for recycling the deep supply of P back to the surface (Simpson, 1970; Ivanoff, 1972 and Giresse, 1980; Baturin, 1981). Such upwellings result from the major ocean current divergences and represent areas of high primary organic productivity. Chow and Mantyla (1965). According to Gulbrandsen and Roberson (1973), the P content of the upwelling water off the Peruvian coast is 2 mg atoms P/1 (0.062 ppm) and Armstrong (1965) reports surface concentrations upto 2.5 mg atoms P/1 (0.077 ppm) in upwellings around Antarctica (Bushinski, 1964 and Pevear, 1966). The source of the Georgia basin in U.S.S.R. phosphate has been debated. Russell and Trueman (1971) proposed oceanic currents as the source, but other authors, like dekeyser (1969); 36t dekeyser and Cook (1972); Cook (1972); Howard (1972) and Fleming (1977) believed that the shallow epicontinental s«a and the depositional enviironments indicated by the sediioentary section leave no scope for applying the upwelling oceanic waters hypothesis originally proposed by Kazakov (1937) and developed by modern workers. Terrestrial run-off (Marsh, 1977), tropical upwellings (Kiramerer and Walsh, 1981), groundwater (D*Elia, et al.# 1981), internal waves, (Andrews, 1983) and endo- upwellings (Tarabili, El, 1969; Rougerie and Wauthy, 1986) Can contribute fixed nitrogen and phosphorus to reefs. Tbe importance of the sources of P depends upon the geographical and geomorphological settings of the reefs (Wiebe, 1987), Kolodny and Kaplan (1970) strongly suggest that even though sea-water may be near, or even in excess of saturation values with respect to carbonate-fluorapatite the precipitation of this mineral in today's ocean is of minor quantitative importance. Erosion rates during Precambrian times (periods of extensive phosphatisation) are estimated to be one-fifth of what is today (Garrels and Mackenzie, 1971). In other words, in the past P-flux might be about 4 million tonnes, P/yr. Global phosphate deposits is now estimated to be about 60 billion tonnes. Thus, Just a few thousand years of continental supply is enought to account for all the economic phosphate deposition and no extra source, such as volcanoes are necessary 362 (Sabramaniah, 1984). The phosphorus content of deeper ocean- water on the average Is 12//Ajq/l^t but it can contain several times that amount in more restricted seas (Baturin, 1978)• Another source of phosphorus in bottom waters is the intersti tial water in sediments (J#R. Morse, written Communication in Burnett and Sheldon* 1979) reported from preliminary analysis of a few areas of marine continental shelf sediments that phosphate fluxes by diffusion from the sediments into the overlying water column reaches an amount 5 x 101 2/ ^ P/yr. These fluxes were measured by concentration gradients between the bottom water and the upper two centimetres of cores (Twenhofel, 1950). In sea-water apatite is also formed from the same carbonates but the latency period is Longer. We think that the crystallization of apatite in sea-water is only possible because bacteria after extract magnesium from the solution, precipitate an intermediate mineral struvite. The apatite is well-crystallized in marine water than in fresh water; and peaks are broader and less intense in marine environment (Lucas, 1984)• Phosphate content in natural waters is usually low, the theoretical thermodynamic solubility of the commonly occurring inorganic orthoorthophosphatp e being 30/xxj 1" of P (Sahgal and Ramesh, 1984), 363 In the study area, the Bijawar remained a sea-basin at least from early to middle Precambrian and it covered large parts of Madhya Pradesh and some parts of Uttar Pradesh during which the phosphate concentration continued. It may be suggested that the basement rocks of the ancient sea-floor belonging to the Bundelkhand Granite Complex might have been the major source of the phosphorus and its associated sediments. On the other hand, as suggested by various authors as above, also the oceanic-basinal waters contributed some amount of phosphorus through the precipitation of apatite as long as the marine conditions prevailed. It is, therefore, like/the importani source of phosphorites in the Bijawar basin was that the oceanic waters besides some river waters. (iii) TiO^ vs. Ratios of total iron/MgO Diagram - It is apparent from the TiO^ vs. ratios of total iron/MgO diagram that the analysis of all the eight samples have a distinct linear trend, Ti02 increasing with the total iron/kgO ratio. This is indicative of crystal fractionation (Glassley, 1974 and Gupta, et al., 1988). In the study area, the Ti02 weight percentages slowly increases with the ratio values of total iron vs. MgO in all four types of phosphorite samples. The ratio values of total Iron vs. KgO varies from 10.01 to 66.80 in shale-phosphorites; 7.41 to 71.85 in secondary-phosphorites; 6.03 to 173.88 in cn m + o 9 <1 (n JS CD o UJ UJ X Q) GL o o UJ X X »- Q. GL in O a: o o o X X X QL Q. O CL u •- r4 ro N4 > O o c Q:: CD in I r~^ c o a* o •^• *o d" Li- 365 1 SHALE PHOSPHORITE + 2 SECONOARY PHOSPHORITE 0 3 IRONSTONE PHOSPHORITE * t, QUARTZ BRECCIA PHOSPHORITE ^ Ti 0, °/o K,0 X FIGURE :135,TR^.GULAR PLOT SHOWING RELATIONSHIP OF Ti 0 - K.O-P.O,. (After PeaJ:e,1975 8. Gupta, etal 1988 ?' 366 ironstone-phosphorites and 7#96, tp 21,25 in quartz-brecciated phosphorites. Most of the values falls above the oceanic trend line in the diagram. It further supported that the ancient dceanic-floor which was Bundelkhand Granite Complex had been the main source of these phosphatic sediments (Figure-134 and Tables-II and XI). (iv) ^^2"^2^'"^2^5 ^^99^^°^ " ^^ ^^® discriminant diagram, Ti02-K20-P20c consistently indicates an oceanic environment {Pearce,- 1975) and similar in TiO^-MnO-P^O^ diagram (Mullen, 1983 and Gupta, et al., 1988). In the study area* the recalculated weight percentages values of Ti02 varies from traces to 4.27; K2O from traces to 11.62; P2O5 fJ^om 84.71 to 99.86 in all four types of phosphorites of the Bijawar basin. The P2O5 content is very high as compared to other two major constituents like Ti02 and K2O in these phosphorites. This trend of these elements towards the corner of P2'^5 i° ^^® diagram further indicated that the source of these phosphorites were of alkaline and oceanic environment which was conducive to the deposition along the continental margins of the basin (Figure-135 and Table-XIV). (v) Ti02-Mno-P2^5 Diagram - The discriminents record plotting in both Mid^-Oceanic ridge basalt and island-arc tholeilte fields (ytillen, 1933 and Gupta, et al., 1988). 367 1 SHALE PHOSPHORITE 2 SECONDARY PHOSPHORIK O 3 IRONSTONE PHOSPHORITE U aUARTZ BRECCIA PHOSPHORITE A MnO 7, f^.-Os^ FIGURE ;i3ffRlANGULAR PLOT SHOWING RELATIONSHIP OF Ti Oj- MnO-P^05«( After Mullen, 1983 & Gupta, etal. 1988) 368 In the study area* the recalculated values in weight percentages of TiO- varies from traces to 4,21; MnO,traces to 1.59 and P2O5/ from 94,51 to 100.in all the foqr types of phosphorite samples. This relationship is also similar as like that of Ti02-K20-P20c diagram. Here again the trends of these phosphorite samples values towards the Po^o, corner in the diagram. This further supported the oceanic source of these phosphorites (Figure-136, and Table-XIV). (vi) AI2O2 - Total Iron - Si02 Diagram - Major element da-ta of Banded Garnet Araphibole rocks were compared with those of the Lake Superior type oxide-facies. Banded Iron Formations (BIP) and Algoma type oxide-facies BIF by Gross (1980) and also with the manganiferous BIF of Sivasumudram area. South India, Mahabaleshwar, et al., quoted by Janardhan, et al. (1986). It is seen that Bijawar B.G.A* rocks are more or less akin to banded iron-formations in chemistry. When plotted in the AI2O3- Fe^O^ - SiO^ diagram of Govett (1966) they fall within the field of Precambrian B.I.F. There are, however, appreciable differences in the major element concentrations in Bijawar B.G.A. rocks from that of the Algoma and Superior types, particularly in respect of AI2O2, MnO, MgO, Fe20^, Si02 and P20^ contents. B^G^A. rocks have higher MnO, MgO, AI2O3 and P2^5 ^^^ lower Fe203 and SiO^ as compared to the Algoma And superior types (Bandhopadhya and Roy, 1987), 369 \ SHALE PH05P0RITE 2 SECONDARY PHOSPHORITE o 3 IRONSTONE PHOSPHORITE * ^ aUARTZ BRECCIA PHOSPHORITE ^ Al«03 ""/o Si02 7o Total Iron*^ '-^o}'^'T7o\T r""""' «^^AT,ONSH,P OF ALO3- 370 1 SHALE PHOSPHORITE ^ 2 SECONDARY PHOSPHORITE ° 3 IRONSTONE PHOSPHORITE • i. aUARTZ BRECCIA PHOSPHORITE^ Si O2 % AI2O3 % KoO% FIGURE : ^TRIANGLE PLOT SHOWING RELATIONSHIP OF Si 0,- MzOs-K^O (After Gulbrandsen, 1966 ) 371 In the study area, the recalculated weight percentage^ values of Al^O^ varies from 2.47 to 62,53; total iron from 13.07 to 71,13; and SiO^ from 12.97 to 76.62 in all four types of phosphorites which mostly falls in the same region except a . few samples of secondary-phosphorites. These values of major constituents which fall in the •Field of Precambrian Iron Formations* confirmed that the 'Gangau Ferruginous Formations* of Bij.awar GJc:oup may be compared with Algoma and L.Superior rock types (Figure-137 and Table-XV). (vii) Si02-Al203-K20 Diagram - The triangular diagram showing the relationships of AI2O3 - KjO - SiO- in the phosphorites of the Phosphoria Formations. The constituents recalculated to 100 weight percentagejs. Itie diagram represents only the SiO^ corner, the full three (3) coBcponent system (Gulbrandsen, 1966). The recalculated 100 weight percentage values of SiO., varies from 23.24 to 93.16? AI2O3, from 4.08 to 70.74; and ICO from traces to 10.37 in all four types of phosphorite samples of the study area. The values of primary phosphorites fall mostly on the Si02 components except a few samples of secondary phosphorites. The trend of the other two components namely, AI2O3 and K2O are towards SiO- corner. This further supports that one of the sources of phosphorites was the Granitic Complex of Bundelkhand (Figure-138 and Table-XV). 372 1 SHALE PHOSPHORITE + 2 SECONDARY PHOSPHORITE 0 3 IRONSTONE PHOSPHORITE • U QUARTZ BRECCIA PHOSPHORITE A Ca 0 X F^A 7, AI.Oj"/ ^^''"'''pTrAir^.r' SHOWING RELATIONSHIP OF Ca 0- FeAAI.O, (After Green and Poldervaat, 1958 ) 373 Considering the findings on the mutual geochemlcal relations among the various major constituents of the Bijawar rocks as discussed above, it Is almost evident that the basement rocks of the Bijawar basin namely, the Bundelkhand Granite Complex have been a major source of most of the chemical constituents of the former (Table-Ill). (viii) CaO-Pe^O^-Al^O. Diagram - On the basis of triangular ^ ^ V2O3 diagram of CaO-Pe20j"^fter Green and Poldervaart (1958), the recalculated 100 weight percentage values of these three con?5onents were plotted. The values varies are CaO, 47.05 to 88.58; AI2O3/ 1.95 to 23.77; Fe 0^, 2.05 to 36.72 in all four types of phosphorite samples in the study area. In the tri angular diagram, most of the data of all three components falls on the comer of CaO only. This indicated that the precipitation of apatite in the Bijawar basin of more calcium-oxide, marine, and shallower environment (Figure-139 and Table-XVl). SUMMARY : The main source of the Hirapur phosphorites is Bundelkhand Granite Complex which is the basement of the Bijawar basin belong to Archean period. Besides this, the other sources of the phosph- rltes may be host rocks of Bijawar Group, local active rivers and their tributaries and sea-basinal waters at the time of phospha- tization processes in the study area. 374 CHAPTER - IX GENESIS OF PHOSPHATIC SEDIMENTS IX,1, GENERAL STATEMENTS : The bulk of the present world production of phosphorites comes from the Palaeozoic and younger sedimentary basins. But the geological environments in India as known today* tend to indicate that the Precambrian or Proterozoic basins, offer better locales for an intensive search. The Proterozoic basins in India covered large areas of the Indian shield? the rock formations of which consist of sediments or metasediments showing affinities from geosynclinal to shallow water or platform covers, either in their vertical or horizontal distribution patterns. The association of phosphatic sediments are mostly with the carbonates, shales or other rock units close to this gross litho-associations (Nath, 1984). Hypothesis on the ortain of marine phosphorites can be grouped into three general categories :- 1. Special events such as catastrophic destruction of life (Murray and Renard, 1891) or volcanic addition of fluorine to the sea (Mansfield, 1940). 2. Direct intraction of land and sea processes, such as introduction of phosphate to the sea from rivers (Pevear, 1966; Bushinski, 1964) and sea-bottom flow of brines from 375 shoreline salt pans to the continental shelves (Hite, 1976). 3, Processes of marine upwellings (Kazakov, 1937; Mckelvey and others, 1953; Gulbrandsen, 1969). Leaking to depo sition of apatite either at the sediaient water interface or diagenetically within the sedime-rs from interstitial water (Baturin, 1971). According to D'Anglejan (1967), the Santo Domingo embay- ments banded on the western (seaward) side by a line of sub marine escarpments which 'limit the free exchange of water between the shelf and the open ocean'. The border-land is of low relief and the climate is semi-arid. By the mixing of currents, an 0^ - deficient phosphate rich layers of water is produced which is displaced into the embayaent. I According to Gulbrandsen (1966), the chemical principles involved in the apatite sea-water equilibrium and the data presented indicate many theoretical modes cf apatite precipi tation. These modes are listed below in two categories :- 1. Precipitation of apatite from normal sea-water : a. precipitation of apatite alone from sea-water saturated only with apatite alone is due to - i) temperature and pH increases cf water - precipitation alone possibly limited by attainment 376 of saturation and precipitation of CaCO^, ii) phosphate addition - increase in supply over the amount that can be held in solution; iii) calcium addition - increase in supply over the amount that can be held in solution. Precipitation alone possibly limited by attainment of saturation and precipitation of CaCOo? iv) Fluorine addition - increase in supply over the amount that can be held in solution; v) increase in salinity due to evaporation - precipitation alone likely limited by attainment of saturation and precipitation of 03003; and vi) contact with previously formed CaCOo - replacement of CaOO^ by apatite continues until solution becomes saturated with both phases. b. Precipitation of apatite alone from sea-water saturated with both apatite and 03003 is due to - i) phosphate addition - increase in supply over the amount that can held in solution. Apatite precipita-' tion results in solution becoming unsaturated with 03003; and ii) Fluorine addition - increase in supply over the amount that can be held in solution. Apatite precipitation results in solution becoming unsaturated with 03003. c. Precipitation of apatite and 03003 together from sea- water saturated with phases is due to - 377 1) tenperature and pH increases; 11) calcium addition - increase In supply over the amount that can be held in solution; ill} phosphate and carbonate addition - increase in supply but in same proportion as their equilibrium amounts in solution; and iv) salinity increase due to evaporation* 2. Precipitation of apatite from abnormal sea-water : Most evidence and thought attest to uniformity of sea- water composition, at least in the latter half of earth history and the world wide distribution of phosphorites throughout the geologic column is conformable with this* view (Rubey, 1951). The fact that phosphogenesis has been episodic has led a number of researchers to suggest fluctuating palaecCceano- graphic conditions as a. control, particularly with regard to the phosphorus content of deep oceanic waters and expanded oxygen - minimum zones as well as general ocean circulation and wind patterns that are climatically controlled (Piper and Codispoti, 1975; Fischer and McArthur, 1977; Sheldon, 1980, 1981; Kolodny, 1981; McArthur and Jenkyns, 1981; Baturin, 1982; Parrish, 1982; Parrish and Curtis, 1982; Riggs, 1984). The palaeogeography is one of the dominant factors strictly controlling the genesis mechanism of phosphate deposits. The physico-chemical characteristics of the phos phorite are different from place to place, %»^ich vary mainly as the pH and the phosphorus concentration depending on the nature of sedimentary environment. Tbe phosphorite is enriched at the Joined location of land, atmosphere and water is the product of the process of reduction —* Oxidation —^ reduction. Only through this process CO2 can be considerably decreased and the phosphorite can be purified (Liang and Chang, 1984). The modes of occurrence of marine apatites, the features and associations of phosphorites and the factors and concepts involved in the formations of phosphorites that have been noted by many investigations (Gulbrandsen, 1969) are summarized briefly and somewhat selectively as follows s- IA) Forms in which apatite is commonly noted - 1} Fish teeth, bones and scales; 2) Reptiles and mammal bones; 3} Shells, eg. Lingula; 4) Carpaces of orthropods; 5) Coprolite; 6) Microcrystalline Aggregate as nodular, pellets, oolites, shell crests and spicular canal fillings; 7) Microcrystalline aggregates as laminae^ lenses, beds and cement; 8) Macrocrystalline subhedra and euhedra (probably diagenetically); 9) Replacement of carbonate shells and 379 bryozoa; 10) Replacement of carbonate minerals (exclusively of shells); and 11) Replacement of woods. (B) Geological features# association factors and concepts related to phosphorite - 1) Organic matter and carbonaceous mudstone high organic productivity - red - tides - mass mortalities; 2) Chert, procellanite and diatomite (Sponge, spicules, diatoms and radiolaria); 3) Carbonate rock; 4) Glauconite? 5) Conglomerate - reworking unconformity; 6) Condensed section - slow deposition and sparse detritals; 7) Upwellings; 8) Warm arid climate - evaporites; 9) Volcanism - bentonites and tuffs; and 10) Platform - miogeosynclines• On the basis of above theories regarding the origin of phosphorites, the genesis aspects of Hirapur-Mardeora phospho rites discussed as below s^ IX.2. GENESIS BASED ON PETROLOGY, PETROGRAPHY AXD PSTROMINERALOGY (1) Due to tropical, physical and chemical processes active on a Precambrian apatite marble formation, primary apatite crystals were removed from the parent rock and deposited in different types of depressions within a thick weathering 380 profile. The primary apatite crystal margins show a micro- crystalline envelope characteristic of coated grains. The envelop may extend towards the centre of grains eventually forming a wholly microcrystalline apatite body out of the initial coated grains thus producing a peloid by the process of grain diminution (Cayeux, 1939, 1941, 1950 and Dahanayake and Subasinghe, 1990). These all features were observed in the primary and secondary phosphorites of Hirapur and supported the tropical to arid climatic conditions in which the physical and chemical processes were involved during and/after phosphatizatlons (2) With prolonged period of weathering, when carbonate was almost completely leached out, other associated minerals were attacked which released additional cations like Al"*" and Fe"*" , in the argillaceous host rocks, these released cations combined with available phosphates and formed crandallite, while in the alumina-poor detrital rocks, fluorapatites remained the dominant phase and developed magnetite-goethite coatings. That iron was not readily available at the time of early phosphate sedimentation is evident from the fact that no iron-phosphate was formed in the sequence. However, in the void-filling type remobilized phospho rites, it seems that some of these voids and/fissures were occupied by ferruginous laminations which have been systemati cally leached and isovolumetrically replaced crystalline apatite 381 grains growing from the margins towards the centre of the void spaces• Such features suggest that small quantity of iron was possibly introduced into the system subsequent to primary phosphate sedimentations, possibly at late diagenetic stages on the sediment-water interface and was subsequently leached out during early stages of weathering. Widespread ferruginous coatings of all the rocks in the Hirapur area is due to regional ferru- glnization process, which seems to have accompanied the regional silicification as the last stages of the geological activity in the region. It is also possible that some iron was introduced in the sediment through epigenetic processes (Banerjee, et al.i*'^^ and Saigal and Banerjee, 1987)• The author is fully agreed with the above observations and possibilities regarding the genesis of Hirapur phosphorites which were earlier suggested by Banerjee, et ai. (1982) and Saigal and Banerjee (1987), (3) The experimental data available on inorganic precipitation of phosphorites (Krumbein and Garrels, 1952; and Gulbrandsen, 1969), pertains in reality to the mineral apatite which is seldom the form in which marine phosphorites occurs. However, presuming that an abiotic precipitation of phosphorites (apatite) should be possible under some geological control? it was thought that apatite may characterize the Precambrian phosphorite deposits, where there was little possibility of contribution of phosphate by the remains of organic hard parts (Giejer, 1962).= In the study 382 area, abiotic phosphorites might have originated due to geological controls and by direct inorganic precipitation during marine environment in the Bijawar basin and this feature also indicated the early Precambrian age of these sediments. (4) Most of the older phosphorite deposits show pronounced laminations on a time scale of probably a few years to a few hundred years with thin laminae of phosphorites alternating with other shale, mudstone, carbonate or chert. These alternations result from local changes, e.g, shifting of river mouths or of morphological features on the shallow sea-bottom, slight changes in the direction and strength of currents, small scale temporary oscillation, variations in the amount of rainfall on the nearby land a variety of similar causes (Kazakov, 1937; McKelvey, 1963; Sheldon, 1964; Bentor, 1980 and Boyle., 1984) • In the study area, the association of apatite in three rock units namely shale, iron stone and quartz-breccia and preservation of primary bedding, currents and cross beddings, laminations, ripple-marks, mudcracks indicated the change of flow direction of Kauthan river, shallow sea-bottom, strength of low sea-basinal currents, temporary oscillations and variations in the rainfall during and/after the precipitation of phosphorites. 383 (5) The apatites of all the ancient phosphorites are charac terized by a high (though varied) degree of crystallinity of the phosphatic minerals diagonised both from the photograph in the SEM and from the results of the study of their fine crystal structure by XRD (Fuller, 1979 and Gilinskaya/ et al., 1984). The variations of crystallinity of apatite in both primary and secondary phosphorites from cement, cryptocrystalline, micro to megacrystalline, pelletal and nodular forms supported the ancient (Early Precambrian) origin of these sediments. (6) The interlayered bedding with thick mud layers, alternating with relatively thin sand layers, which is conspicuous in Bijawar is common in sediments of intertidal flats (Reineck and Singh, 1980 and Boyle, 1984). The presence of mudstone and/claystones layerings of phosphorites within the host rocks of Bijawar Group in the Hirapur area may be the products of intertidal flats which is mostly occupied the borderland margins of Bijawar basin. (7) Authigenic phosphorite and phosphate rich materials form in shallow, restricted lagoonal or estuarine environments, in low latitudes ( < 40^) adjacent to a hot and arid hinterland. Intense wind induced upwelling currents. Apatite is precipitated directly from the water column to form layered or massive phos phorites or apatite may grow or precipitate within interstices 384 in the sediment to form phosphatic packstones. Phosphate pellets probably formed by accretion at the water/sediment interface if suitable nuclie are available or granular material may be produced by fragmentation of newly formed phosphatic packstone during periodic storms (Pughistor, 1960; Okada, 1960; Emilson, 1961; Bushinski, 1964; Dasilova, 1973; Dall'Aglio, et al., 1974; Muktinath, 1974; Burnett, 1978; Banerjee and Saigal, 1980; Cook, 1980; Birch, 1980; Peacor, et al.# 1984; and Proshlyalaova, et al 1987). In the study area# the presence of pelletal and non- pelletal cellophane and crandallite are the products of shallow, restricted circulation of water, hot and arid hinterland, up- welling currents and direct inorganic precipitation and remobi- lization and reprecipitations in the voids, fissures, etc. (8) In northern Maranhao, aluminium rich phosphate deposits resulting from laterite weathering are known (Cook, 1972 and Notholt and Hartley, 1983). In the study area, the formation of crandallite (calcium-aluminium-phosphate) in the samples of secondary phosphorites are the product of lateritization, weathering, erosion of primary ores and redepositional processes, etc, (9) Palaeobasinal reconstruction of the Udaipur and Jhabua area suggest the existence of a shallow epicontinental sea 385 (Banerjee, 1978,b) and the basinal analysis carried out through sedimentary structures indicates an all prevading shallow sea during the phosphorite formation XBanerjee, et al., 1980). It is true the phosphorite can form mainly in marine environment, studies of various Indian deposits and several other deposits of the world clearly suggest that only certain well-defined environments were responsible for commercial accumulations of phosphorite (McConnell, 1938; Gulbrandsen, 1969; McArthur, 1978; Stowasser, 1979; Riggs, 1979 and Banerjee, et al., 1980). The sedimentary and structural features of phosphorites of Bijawar basin also supported the shallow epicontinental sea and marine conditions during early Proterozoic time. (10) The angularity and large size of many of the phosphorite nodules recovered suggesting absence of transportation for any great distance and the similarly of the sedimentary components found within the nodules to the surrounding unconsolidated sediments suggests that these Agulhas Bank phosphorites were formed essentially in situ (Carozzi, i960 and Parker, 1975). The poor and rare occurrences of nodular shaped apatite in the phosphorites of Hirapur area indicated the less transportation of the pelletal cellophane and crandallite. The more angularity particularly in the quartz-brecciated phosphorites also supported the above observations of Parker (1975). 387 In the study area# the mild leaching and/weathering of primary phosphorite particularly shale phosphorite indicated the formation of calc-aluminous phosphate mineral like crandallite which is associated with goethitic coatings and minor constituents as quartz, muscovite, hematite, limonite, iron-oxide, etc. The presence of goethite in these phosphorite may be the product of dissolution of kaolinite and iron-bearing minerals. The episodes of weathering processes might have taken place just after and/at the time of deposition of primary phosphorites by means of ground water action and movement of sea-basinal tides, waves and long shore currents. (12) Most earlier workers had called on primary sedimentation for marine phosphorites, although reworking or winnowing to produce higher grade deposits has been advocated for the Florida deposits (Altschuler, et al.# 1964; D'AngliJan, 1968 and Lehr, et al., 1968; Cheney, et al., 1979) and the Permian deposits of the Rocky mountains (Sheldon, 1957, 1963; Cressman and Swanson, 1964; Bushinski, 1964 and Cook, 1967). Baturin (1971 and 1978); Sumerhayes, et al. (1976); Riggs (1979) and Howard (1984) hypothesis of upwelling currents, diagenetic precipitation - low sea-level reworking received much support. The reworking or winnowing of primary shale phosphorites which produced a higher grade secondary phosphorites in the Hlrapur area. (13) The intimate association of magnetite in phosphate ores reflects the moderate reducing environment in discharge basin (Huber, 1959; Harold, 1966 and Curtis, et al.# 1^68), The presence of few grains of magnetite particularly in the iron stone phosphorites indicated the low grade metanorphism and moderate reducing environment in the Bijawar basin. (14) Associated with phosphatic ovules and often induced in • them are particles of the detrital quartz, mica-flakes and clay minerals indicating a simultaneously deposition of these minerals (Carozzi, I960; Folk, 1962 and 1968). In the study area, the associations of gangue minerals like quartz, mica-flakes, kaolinite, hematite, magnetite, goethite, limonite, iron-oxide and secondary silica indicated the contemporaneous deposition of these minerals in the Bijawar basin. (15) The phosphorite beds (clayey sand with variable amounts of sedimentary apatite pellets) in the upper part of the Bone Valley Formation have been extensively altered by groundwater over large areas. In the upper part of the zone of weathered or leached zone, apatite pellets have been completely dissolved and the rock is now a porous sand or sandstone with a cementing matrix of clay and secondary aluminium-phosphate minerals. Partly leached, soft white apatite pellets still remains at the base of 389 the leached zone, secondary aluminium-phosphate minerals consist of wavellite, (Al3(PO^)2(OH)3.5H20); crandallite (CaAl3(PO^)2 (OH)5.H20) and millisite INa* K)CaAlg(PO^)^(OH)g.3H20); wavellite is the dominant phosphate in the upper part of the zone and the crandallite is abundant below. Because of its mineral content, the leached zone has become known as Al-phosphate zone (Espenshade and Spencer, 1963 and PettiJohn, 1969). In the study area* the weathered and/leached zone looks like a sandy-sandstone-shale in which the soft constitutes of the rock has been removed by groundwater action and this zone particularly in the field are at the lower horizons in which the primary apatite-carbonate phase (Collophane) has been altered into the Calc-Aluminium- phosphate that is crandallite. The collophane phase is dominant throughout in the upper zone. (16) Kaolinite and goethite are the two main new-formed minerals found in the ferruginized zone. Kaolinite is formed during the weathering of mica according to the reactions :- (K2AlgSigO2Q(OH)^+3H20 +3H2O + 2H*" • 3(Al2Si20^(OH)^ + 2K (Muscovite) (kaolinite) This is a classifical reaction of Kaolinite formation under moderating leaching and acidic weathering conditions (Millot, 1964; Tyrrell, 1980 and Reedman, 1984). Goethite is found along cracks and also in the whole volume of the ortho- 330 gneiss, especially on biotites. This weathering of biotite to to goethite means that ferrous-iron is oxidized according to the reaction s aPe^"*" + i/202 + 4(OH)* ~--> 2(FeO,OH) + H^O (Goethite) The fact that iron remains mainly in situ on biotites and is not carried away shows that weathering has occurred here under near neutral pH conditions (Garrels and Christ, 1965). Hydrolysis reactions/ buffer that pH and allow the in situ goethitization of biotite which could be written from a combination of above reactions s- (Biotite) + (H2O) + (O2) ^ (Kaolinite) + (Goethite) + (K"*", Mg"*""^ ). Similarly, the weathering of K-feldspars also gives rise to kaolinite on the following reactions s- 2(KAlSi30Q) + H2O + 2H'*' ^ (AI281205 (OH) ^ + ^SiOj + 2K"*' (K-feldspars) (Kaolinite) In the study area, the associations of iron and clay bearing minerals namely goethite and kaolinite in the phos phorite samples which were studied under the microscope and further verified by XRD analysis supported the above reactions in which the muscovite, biotite and K-feldspars altered into goethite and kaolinite, etc. This alteration and/neoformations 391 of minerals might have been due to mild episodes of leaching and/ weathering of the primary ores. (17) Apatite mudstone has been reported by a number of workers. Freas and Riggs (1965), postulated that apatite mudstone of the Miocene-Pliocene Florida deposits forms directly frem sea-water in the very shallow parts (Riggs, 1979 and Trompette, et al., 1980). Russell and Trueman (1971) and Howard and Hough (1979) agreed with Freas and Riggs (1965), in their interpretation of the apatite mudstone. of the Cambrian deposits of Queensland, Australia, however, they noted that the apatite-mudstone dees not contain organic matter or sulphide minerals, which occur in the pelletal rocks of the same formations. On the other hand Dekeyser and Cook (1972) - postulated that the apatite mudstone of Queensland were deposited from phosphate bearing surface and groundwaters moving into the intertidal or supratidal zone, becoming more alkaline and precipitating apatite within the sediments or more commonly at the surface when they were also subject to weathering (McKelvey, 1967; Ager, 1974). Thus, it seems difficult to attribute the formation of the apatite-oad to anything ether than direct precipitation from shallow-water (Sheldon, 1980). In the study ar^a, the absence of organic content stromatolites, carbonaceous matter and pyrite in the phosphorite samples supported the direct, inorganic precipitation ScjCt in the alkaline and on the shallower part of the basin which may ranges from intertidal to supratidal zones. The sea-basinal tides and water-waves and rainfall might be responsible for the weather ing of the ores in the area. (18) Limonite frequently occurred as a replacement of sericite. Limonite-clay veinlets and embayment in cellophane were also common These are believed to have resulted, at least in part from replace ment of original sericite and clay. Wavellite veinlets, guided by fractures and by cellophane pellets boundaries were also observed in few samples (Mabie and Hess, 1974 and Sankaran, et al.r 1980). The phosphorite samples of Hirapur area are also contain limonite and iron-oxides in the fissures and voids and embedded in the huge masses of cellophanes. In the secondary phosphorite sanqjles, the crandallite occurs as thin veinlets in the limonitic masses. These occurrences might have taken place due to replacement of sericite and clay minerals. (19) There are two models of the deposition of phosphorite in the medium - 1) In case that the medium varies from slightly acidic to alkaline, the depositional order will be (from bottom to top); dolomite, phosphorite, limestone (calcite) and silica (quartzite, chert/ etc.); 2) In case the medium varies from alkaline to acidic nature, the depositional order will be (from bottom to top); silica/ limestone, phosphorite and dolomite (Liang and Chang, 1984). In the study area, the sequence of 333 of deposition from bottom to top are - quartzite, sandstone, limestone, dolomite, shale, ironstones, quartz-breccia and phosphorites and it indicated the acidic and alkaline environment of the sedimentary basin during the period of phosphatization. (20) The close association of the fragmental phosphorites and the brecciated phosphorite suggest that they have a linked story of their formation. Further, the higher Po^S c^^^^f^^ (+33% mainly in Jhamarkotra) of the fragmental phosphorite and the negligible amount of matrix material present in it suggest that it is a residual type of phosphorite (Chauhan and Sisodia, 1984). In the study area, the secondary shaley phosphorites particularly have low content of gangue minerals and on the other hand, the phosphate constituents are most dominating supported the residual type of deposits in the area. At places, the other phosphorites namely ironstone and quartz-breccia are also look like a residual type. (21) Hematite, Ti-hematite, ilmenite and rutile formed by oxidation process (Hayes, 1915. Carozzi, 1960 and Helvaci, 1984), The microfacies which consists of Tal Chert, phosphorite, shale members, etc. in Mussoorie area represent facies changes from intertidal to supratidal to protected tidal flat or shallow lagoon with restricted circulation of water,(Fisher, 1964; 394 Hoffman, 1976; Banerjee, 1978^a; and Schidlowskii, 1979; Singh, et al., 1980; Banerjee and Klemm, 1985; Tlwari and Qureshi, 1985; Schmitt and Thiry, 1987). The petrological variations are easily correlatable to the bulk chemistry of phosphorite and such correlation also explain satisfactorily the association of other mineral phases which occur with one particular phosphorite in response to either the palaeocliraatic and palaeobathymetric conditions to post-depositional processes (Saigal and Banerjee, 1987), The contacts between the sericite layers and the recrystallized apatite are always sharp, which suggest that the apatite recrystallization, remobilization and void-filling episodes preceded the formation of sericite in the rock developed as a result of local tectonism and metamorphism. In the Hirapur phosphorites, the occurrences of hematite, limonite, goethite, iron-oxides and few grains of rutile and ilmenite supported the highly oxidization environment of the basin. The association of phosphorites with shales, ironstones and quartz-breccia and lithofacies variations indicated the intertidal to supratidal to protected tidal flat with restricted circulation. This also indicated that the palaeoclimatic and palaeo-bathymetric conditions to post-depositional processes of the Bijawar basin. In secondary' phosphorite samples the recrys tallized apatite into the crandallite forms, further supported the weathering, leaching, remobilization, reprecipitation in the 395 void fillings which might have developed by local tectonic activity and weak metamoxphic processes. (22) An assumption made by some workers is that pellets and oolites must be rolled out by currents to give them their round shape (Folk, 1959; Sheldon, 1980; Bagati'and Mundepi, 1984). The laminations indicated that the environment of phosphorite deposition had much less energy, leading to the conclusion that size distribution of phosphorites is not due to mechanical sorting by currents but a primary size distribution due to processes of accretionary growth (Gebelien, 1960; Basu, 1984). Freas and Riggs (1965, 1968); Baturin, (19713; and Riggs, (1979^3) proposed that the pellets of the Florida phosphorite deposits were formed by erosion of an apatite-mud or microsphorite and subsequent rounding abrasion as the sediment was being reworked, (Tooms, et al», 1969; Reeves and Saadi, 1971; Price and Calvert, 1977). Well developed, apatite pellets form diagenetically in the muds. (Heimbach, et al.# 1974; Lucas, et al./ 1979jC; Birch, 1980 and Lucas, et al., 1980 and Lamboy, 1982). Mostly oolites are marine, whereas primary fluvial and lacustrine oolites have also been reported (Bradley, 1964;v McGannon, 1975). The petrograpHic and sedimentological study of these rocks and oolites bearing horizons include the work of Rao (1969); Awasthl (1970); Kharakwal and Kumar (l970); Bhatta- charya and Chanda (1971); Bassi and Vatsa (1971); Rao and Rao 396 (1971); Kharakwal and Bagati (1974, 1975 and 1976); Singh and Rao (1978) and Bagati and Kharakwal (1979), The amorphous-apatite occurs as microscopic spherulitic aggregates. In crossed-nicols, it is isotropic characterized by extinction. The cryptocrystalline apatite occurs as aggregates of microlitic grains. They are homogenous and generally 0,001 - 0.003 mm in diameter but the boundaries between them are obscure. This reflects the initial crystallization phase of the apatite. The microcrystalline apatite shows accicular or fibrous microcrystals and obscure hexagonal prisms on the surface of oolites. According to the development of crystal form, thin apatite seems to be the product of the recrystallization of microcrystalline apatite (Liang and Chang, 1984). In the Hirapur area, the occurrences of ovulitic to oolitic shaped cellophane indicated the poor transportfon rounding- and accretions of phosphatic minerals in the phosphorite samples. The pelletal shaped cellophane and crandallite are of reworking, well crystallized and diagenetic origin. The presence of amorphous, crypto to micro to ;.:: ::u.^ ;,: /.. macrosphorite phosphorites in this area. The presence of thin laminations in few of the samples indicated the very low energy and shallow water and marine conditions of the Bijawar basinal-sea. (23) several workers like Reineck (1969); Shinn (1970); Cook (1972); Klein.'(1975); Laporte (1975); Ruset 'l977); 397 Flemmlng (1977); and Erlkson (1977) considered sedimentary structures like herring bone current bedding, lenticular- £laser-wavy bedding, cross and thin parallel laminae, ripple- marks, mud-cracks, etc. to be a good indicators of shallow waters and tidal depositional features (Banerjee, 1971; Valdlya* 1972; Munshi, et al., 1973; Reineck and Singh, 1975; Horidyski, 1976; Banerjee and Narain, 1976; Smirnov, 1976; Friedman and Sanders, 1978; Israili, .^1978; Southgate, 1980; Banerjee and Rawat, 1980; Bashyal, 1984 and Bhattacharya and Sengupta, 1984)• The presence of all these preserved sedimentary structures in the Hirapur phosphorites further supported the above observa tions of all the earlier workers• (24) Both pelletal phosphorite and glauconitized pelletal phosphorite show an evidence of having originated by direct, inorganic precipitation of apatite. There is no evidence of replacement of calcium-carbonate; associated limestone fragments are unaltered. The precipitation occurred in shallow, marine water is suggested by the occurrence of unaltered laminated micrite blocks which possess mud-cracked collophane surfaces (Fuller, 1979; Howard and Hough, 1979; Banerjee, 1980). The pelletal phosphorites are of authigenic precipitation in quite and protected environment. The phosphorite of Hirapur-basin area were originated along the restricted shoals in littoral basins . of the instracratonic-sea which fringed the margins of the n% Bundelkhand Granitic Craton (Banerjee, et al., 1982 and Viqar and Banerjee, 1986). In the study area, the presence of pelletal phosphorites indicated the authigenic, direct, inorganic precipitation of primary phosphorites in the shallower, marine, restricted shoals in littoral basins of intracratonic-sea which fringed the margins of the Bundelkhand Granitic craton. The absence of appreciable content of apatite in the limestones and dolomites indicated that no replacement of carbonate by phosphate has taJceiD place In this basin. (25) Sheldon (1964, a) was the first to point out that the palaeolatitudinal distribution of ancient phosphorites matches the latitudinal distribution of young phosphorites, with both falling within 40*^ of the equator. Subsequently, Sheldon (1964, b), and later Freas and Eckstrom (1968), applied palaeolatitudes and palaeogeographic reconstructions to the search for new phosphate deposits. The palaeolatitudes of all deposits show a spread from about O to 7Cf but with a clear maximum within 20° of the palaeo- equator. When only the major deposits are taken, the two latitude peak is more clearly defined, with a peak between 10 to 2 0° from the equator. This support the view that phosphate deposition is most abundant at low-latitude locations with a preference for a sub-equatorial (10 to 20°) location rather than an equatorial (0 - 10°) site (Cook and McElhinny, 1979; Birch, 1980; Al-Bassam, et al., 1983). 399 The pala6oclimate was warm and dry suggesting a low latitudes epicontinental sea along the ancient continental margins. Before the overlap of the Lluplng Formation on the Daxlng Formation, there had been an uplift in the region. After that the crust became more stable, completing the transformation of geosyncline to platform and favouring the deposition of phosphorite (Long Kang and zhendong, 1968). The occurrences of phosphorites in Hlrapur-Mardeora area, districts Sagar and Chhattarpur (M.P,), India fails on the latitudes which varies from 24*^19*0" to 24*^23*0" Indicated the palaeogeographlc, palaeocllmatic conditions as warm and dry with low latitudes, epicontinental sea-basin along the ancient continental margin. It may also be suggested that the basinal uplifting might have formed the geosyncllnal to platform structure on which the phosphatlzation process took place. (26) Most of the Proterozoic phosphorites (barring Bljawar phosphorites) are greyish black mlcrosphorite, closely associated with manganese and iron-oxides (mainly goethite) in Rajasthan and basemetal sulphides in Cuddapah. The shallow littoral environment (Banerjee, 1971; Chauhan, 1979; Banerjee, et al., 1980) explains abundance of Mn and iron«^oxides and the presence of organic matter. Complete absence of organic-matter in Bljawar phosphorite and red-dish- brown colour of the ore indicate a m shallow water and highly oxidizing environment (Casteno and Garrels, 1950; Saigal, 1982; Banerjee, et al.* 1982; Saigal and Banerjee, 1987). The coarse clastic grains, the presence of kaolinite and the irregular bedding of the cellophane raudstone indicate that they were deposited in near-shore environments and were subject to periodic influx of terrigenous debris (Russell and Trueman, 1971). Cornet (1905), has demonstrated that the brown colour is due to the oxidized state of the endorsed iron- minerals and that fresh, unoxidized material collected from below the water table as grey-blue in colour and contains abundant disseminated pyrite. The occurrence of pyrite and reduced iron are clear indicators of an aerobic conditions within phosphatic chalk sediments. Supergene alteration generally increases the lightness value, at first around the surface of the grains or along fractures then migrates inward through the grain eliminating the primary colouring matter»(Riggs, 1979). Abundant iron-oxide indicates oxidizing conditions, whereas pyritic foraminiferal fillings suggest reducing conditions in microenvironment (Krauskopf, 1959; Burner, 1971; Summerhayes, 1972; Rao, et al., 1974; McArther, 1978; Birch, 1980; Bentor, 1980; Jarvis, 1980; Bhargava and Ahluwalia, 1980; Khan, et al., 1981; Jack, 1981; Al-Bassam, et al., 1983; Bhattacharya and Sengupta, 1984; Patwardhan and Panchel, 1984; and Tiwari and Qureshi, 1985). lot The open shelf in turn faced deep water ^uxinic basin in which pyrite, carbonaceous shales were deposited under acidic and strongly reducing conditions, (Gulbrandsen and Pettijohn, 1957; Mason, 1966; Pettijohn, 1969; Beaukes, 1984), There is a close link between phosphate occurrence and the complex clay- minerals* glauconite, both tending to occur at horizons of reduced sedimentation (Fuller, 1979). A horizon of black shale associated with phosphorites suggests a gradual change in the basinal conditions form euxinic (black-shale to aerated intertidal environment at the time of deposition (red-shale)(Kanwar and Ahluwalia, 1980; Liang and Chang, 1984 and Verma, 1984). In the stady area, the Hirapur phosphorites have similar petrological teatures, also suggests a gradual change in the basinal conditions from euxinic to aerated intertidal environment at the time of their deposition as suggested by the above earlier I workers• IX,3. GENESIS BASED ON MAJOR IONS GEOCHEMISTRY : The genetic aspects of phosphorites of the study area based on major elements distributions and their mutual relationships are given as below :- (1) In the study area, the phosphatization might have dependent on the physico-che'mical conditions of the basinal sea-waters and m it took place during shallower, marine environment. The absence of organic matter supported the direct inorganic precipitation of phosphorites (Mason/ 1958; Lerman and others, 1975 and PettiJohn, 1984). (2) In the study area, during early Precanibrian time the oxygens-minimum layer might have present on the oceanic floor and through slow oceanic upwelling currents, it might have exposed in the shallower parts of the Biajwar basin in which an highly oxidizing environment helped the precipitation of phos phorites. On the other hand, slow sedimentation and poor supply of detrital material may be another factor for the final phos- phatization of apatites in these rocks (Emelyanov and Senin, 1969; Piper and Codispoti, 1975; Fischer and McArthur, 1979; Jarvis,1980). (3) Phosphatization within the Bijawar basin also took place on the geosynclinal to stable platform during warm and dry palaeoclimatic conditions in which the upwellings currents might have brought the phosphorus content from deeper cold regions of tlje basin. On the other hand, the associations of apatites with shales, ironstones, quartz-breccia and secondary phosphorites further supported the above observations (Long Kang and Zhendong, 1988). (4) The secondary phosphorites of Hlrapur area, might have formed due to change of eustatic/tectonlc instability of the 403 . continental margins and transgressive and/regressive processes of Bijawar sea-basin. Itiis also supported the dlagenetic formation of these phosphorites (Summerhayes, 1970; Pasho, 1972; Parker, 1975; Cullen, 1978; Birch, 1979^b and 1980). (5) In the Bijawar basin, besides upvrelling currents, tiie formation of phosphorites by primary and diagenetic processes might have controlled by trapping mechanism of phosphorus content by palaeotopographic, palaeoclimatic, palaeogeographic aai palaeo- tectonic conditions of the basin (Benraore, et al«/ 1984; Patwardhan and Panchel, 1980). (6) To much variations in the P2^5 concentrations in the sanples of phosphatic bearing shales, ironstones, quartz-breccia and remobilized minerals indicated the long range of clinatic conditions and highly oxidizing to slightly reducing environment of the sedimentary basin (Parker, 1975; Lucas and Prevot, 1975; Mulline and Rasch, 1985). (7) In the study area, an increase of temperature and decrease of pressure and presence of CO2. and MgO ions, alkalinity and pH and Eh of sea-water favoured the direct, inorganic, chemical precipitation of phosphorites (Goldberg and Parker, I960: Kramer, 1960; Roberson, 1966; Krauskopf, 1967; Gulbrandsea, 1969; Atlas, 1975; Sheldon, 1980 and Khan, et al., 1981). 404 (8) In the study area* more leaching was observed in the shaley phosphorites as compared to iron-stones and quartz- brecciated phosphorites and presence of very high P^^S co'^^®'it in the leached/remobillzed/vein/void/fissure fillings type phosphorite indicated that the weak minerals like micas and feldspars* and to some extent quartz has been removed from the rock assemblages. The very mtld episodes of weathering is also seen in other two types (ironstone and quartz-breccia) of phosphorites (Choudhuri, et al./ 1980? Sant and Sherma/ 1984). (9) in the study area, the higher content of CaO in the phosphorite san^ples supported the basic chemical con^josition of apatite which were mostly precipitated by direct, inorganic process during early Precambrian age (Krauskopf, 1967; Mont gomery, 1979)• (10) The author also agreed with the observations of Banerjec, et al., (1982) regarding decarbonation of phosphorites at same places in which part of the CO2 has been lost. (11) In the study area, the overall poor content of CO2 and abundance of crandallite as compared to cellophanes particularly in the secondary phosphorite sanples may be due to repeated and/ episodes of metamorphic cycle and tectonism beside weathering process in the sedimentary depositional microenvironments (Rooney and Kerr, 1969; Dayal, et al., 1984; Sliskovskiy, et al., 1967; Lehr, et al., 1967; Tooms, et al., 1969). 405 (12) In the study area, the presence of phosphorite bands may Indicate the above and below oxygen-minimum zone of the Bijawar basin (Veeh, et al., 1973). (13) The presence of low content of AI2O2 in the san^les of phosphorites Indicated the arid to humid climatic conditions. The origin of crandallite in the secondary phosphorites by mutual ionic substitution and goethitic coatings which were explained by early workers, the author also agreed with them (Cook, 1972: Birch, 1980; Lucas, et al.# 1980; Banerjee, et al., 1982 and Saigal and Banerjee, 1987). (14) In the study area, the Gangau Iron Formation which are phosphatic at places are the product of near shore, oxidizing environment. The presence of hematite, goethite, limonite and iron-oxides content indicated the humid to arid, marine, shallower conditions of the Bijawar basin (Hubber and Garrels, 1953; James, 1954; Johnson and Swett, 1974; Puller, 1979 and Morris, 1986; and Bandyopadhyay and Roy, 1987), (15) In the Bijawar basin, the presence of quartz and secondary silica content might have been controlled by pH of the basinal waters, and association of COj in the carbonate-fluorapatite phase of cellophane and remobilization and reprecipitation of crandallite in these phosphorite indicated the near-shore deposition environment in which the shrinkage cracks were developed 406 in the later phase. These features support the dlagenetic origin of these phosphorites (Khan, et al.# 1981; Saigal and Banerjee, 1987 and Banerjee and Saigal, 1988). (16) The phosphorite sansples of the study area, containing higher concentrations of alkalies, which suggested the high palaeosalinity and restricted circulation within the Bijawar basin. On the other hand, it can also be suggested that the higher content of alkalies may be due to weak substitution in the apatite crystal lattices and/adsorption on the mineral surfaces and presence of some detrital grains (Smirnov, et al.# 1962; McArthur, 1978; Banerjee, 1982; Banerjee, et al«, 1982 and 1984 and Saigal and Banerjee, 1987). (17) The presence of MgO in the phosphorite samples indicated that some part of the MgO has been substituted inside the apatite crystal lattices and had adsorbed on the mineral surfaces of apatite and by huge masses of clay and iron-bearing minerals in marine insterstitlal waters. This is known as inhibition processes of apatite. The diagenetic aspects of the phosphorites further supported by scavanger activity to goethite within the Bijawar s*4u-basin (Martin and Harris, 1970; Parker and Siesser, 1972; Sholkovits, 1973; Burnett, 1977; Birch, 1980; Mullins and Rasch, 1985). 407 (18) The presence of T±02 In the sanples of phosphorites supported by association of ilmenite and rutile grains in the matrix. Titanium may also be sUDstituted inside the apatite crystal lattices; adsorbed and absorbed in the gangue and phosphate minerals during shallower, marine, oxidizing basinal conditions (McConnell, 1973; Howard and Hough, 1979; Altschuler, 1980; Rasmy and Easily, 1983). (19) Likia, Na# K, Ti, Mg, manganese also behaved similarly in all phosphorite san^les of the study area. This may be present^adsorbed, absorbed, substituted and discrete mineral phases in the phosphorite samples. These changes might have taken place under shallower-water and highly oxidizing environ mental conditions of the Bijawar basin (Krauskopf, 1969; Banerjee, at al.r 1982 and Saigal and Banerjee, 1987 and Banerjee and Saigal# 1988). (20) In the study area# the progressive positive relationship between CaO and Po^c supported the internal structure of apatite in which the mutual substitution is well documented. This rela tionship also indicated the diagenetic origin of phosphorites during highly oxidizing, alkaline basinal sea waters (Cruft, 1966; Vallentyne, 1974; Howard and Hough, 1979; Altschuler, 1980 and Khan, et al*# 1981). (21) In the study area# the CO2 plot against ^2^5 ^^^^^' random, linear but progressive positive relationship in the phosphorite sanples, and this type of relationship indicated -2 that - i) support the chemical formula of apatite in which CO^ is an inqportant part of crystal lattice of apatites; ii) mutual -3 -2 ionic substitution of PO^ by CO3 in which the chemical reaction +2 +1 is balanced by Ca by Na by coupled substitution within the basin before final precipitation of phosphorites; iii) the random and/linear relationship in few samples, indicated the episodes of hidden mild weathering of these primary phosphorites which might have taken just and/after the final or completion of phosphatiza- tion processes in the Bijawar basin; iv) these relationships farther supported the diagenesis process of phosphorites which might have taken during low temperate, humid, marine, in the restricted epicontinental-sea shoals regions of the Bijawar basin; v) mutual relationship of CO^ and PO^ also supported the better crystallinity of apatite minerals which varies from crypto- crystalline to micro, macro, megacrystalline, ovulitic to oolitic, pelletal, nodular, etc. which also supported the pseudoisotropic characteristics of cellophane and crandallite in the ancient time (early Proterozoic)(Alder, et al., 1963; Youssef, 1965; Kimrey, 1965; Gulbrandsen, 1966; 1970; Sinpson, 1966; Gibson, 1967; Roney and Kerr, 1967; LeGeros, et al-# 1967; Schmatz and Swanson, 1969; Berner, 1971; McArthur, 1978, 1985; Banerjee, ' 1979; Subramanian, 1980; Manheim, et al./ 1984; Banerjee, et al., 1982; Manheim and Gulbrandsen. 1983). 409 (22) In the study area* the weaker negative correlation of ^2^5 ^^^^ ^^2^3 supported the presence of mineralogical assem blages of gangue minerals in the phosphorites. Secondly, the episodes of weathering of primary phosphorites exist the Aluminium (AI"*" ) content which might have replaced the part +2 of the calcium (Ca ) from the apatite crystal lattices and gave rise to crandallite (cal-al-carbonate-phosphate) and kaolinite - a middle stage secondary minerals. The absence of millisite (final- product of clay mineral) and wavellite (final product of aluminium-phosphate) in the samples of Hirapur area indicated that there is no final neomineralization processes in this area. This process might have not completed by complete lithification of phosphorites due to tectonic uplifting base of the Bijawar basin (Twenhofel, 1950; Heinrich, 1954? Vallfentyne, 1974; Banerjee, et al.# 1982; Rao, et al., 1987). (23) The weak progressive positive relationship in the samples of phosphorites indicated the minor scale substitution of PO- and CO^ by OH radicals inside the apatite crystal lattices. This also indicated the direct, inorganic precipitation within the pore-waters of the apatite and its gangue minerals. The mild leaching/weathering and winnowing processes also explained by the above correlation which might have taken due to sea-level fluctuations of syntectonism, etc. (Simpson, 1966; Burnett, 1977). (24) In the study area# ^o^S ^^^^° random and positive relation ship with ^32^ in primary and secondary phosphorite sanples. The coupled and balanced chemical substitutions between Ka and S +2 +5 by Ca and P is not possible due to absence of sulphide bearing (pyrite, etc.) minerals in the saiqples« The random relationship indicated the humid to arid climatic conditions at the time of deposition which enhanced the rate of weathering prior to deposition. The high crystallinity sizes of cellophanes parti cularly in primary phosphorites and crandallite in secondary phosphorites indicated very less substitution processes in the area# although these phosphorites belong to early Proterozoic age. Less substitution also supported the on-shore deposition of phosphorites within the Bijawar basin. Much variations in the rocks-mineralogy of phosphorites in the area« may be due to sub-aerial mild weathering processes which is in fact localised one (Jacob, 19,33; Simpson* 1964; Ronov, et al.« 1965; Lehr« et al«« 1968; Gulbrandsen, 1969; Cook, 1972; Parker, 1975? Howard and Hough, 1979; Srivastava and Banerjee, 1981).. (25) In the study area, ^2*^5 ^^^"^ random and weak negative correlation with if^O in the primary phosphorites but progressxve positive in secondary phosphorite samples. In primary, the above relationship further confirmed the internal chemical structure of apatite (cellophane) and in secondary it may be possible that the minor amount of K2O has been substituted by CaO and Na2 0 due to episodes of weathering processes (Cook, 1972). 411 (26) In the stady area« the P2^5 shows weak to strong negative correlation with ?®2^3 ^^^ ^®^ ^" ^^^ four types of phosphorite sanipliss. This rela^tlonship confirms the observations of Cook (1972) that iron belongs to outside position of the apatite lattices and is a product of marine, highly oxidizing and shallower parts of the 'basinal-sea* This may be due to lateri- tization of primary phosphorite* ores which belong to weathering profiles in the area* This also confirmed the predeposition of hematite, magnetite, limonite, etc. and goethitic coatings, ferruginous cement and iron-oxides by secondary enrichment in these phosphorites. The part of the phosphatic content might have adsorbed by the iron-oxide and clay bearing minerals which are the gangue constituents of the phosphorites (Olsen, 1966; Altschuler, et al.* 1967; Cook, 1972; Cruft, 1972; Laajoki and Saikkonen, 1977; Cook and McElhinny, 1979; Shangqing, 1984; Laajoki, 1986; Banerjee and Saigal# 1981). (27) In the Hirapur phosphorites, ^2^5 shows a negative coherence with SiO^ %rtiich confirmed the external location of SiO- in the • apatite lattices and mutual substitution of PO^ by SiO. during highly oxidizing, marine, shallower parts of the Bijawar basin. ^ This substitution may be due to closer ionic radii of Si"*" and +5 P and charges of silica and phosphate as suggested by several earlier workers. Besides, above the observations and suggestions, author also agreed with Baneree, et al. (1982) stated that the m secondary silica precipitation in the phosphorites of Hirapur axrea# controlled by diagenetic processes (Cruft, 1966; Cook/ 1972; Gerasimovskiy, et al.# 1973;. Manheim, et al.#.1980; Khan, et al*# 1981; Banerjee, et al., 1982 and Axelford, et al., 1984). (28) In the Hirapur phosphorite sarnples, P^^S ^^^^^ ® random and negative correlation with MnO and indicated the external position in the apatite lattice which might have introduced by weathering, etc* and it also indicated that MnO has no chemical affinity with P2^5' "^^^^ relationship also indicated the adsorp tion of MnO onto the mineral surfaces by secondary enrichment processes during high oxidizing to slightly reducing environment in the Bijawar basin (Cook, 1972; Banerjee, et al», 1984; Rao, et al., 1987 and Banerjee and Saigal, 1988}• (29) In the study area, Po^S s^*^*'^ ® negative correlation with MgO like K2O, ^62^3* ^®^' ^'^^' ®'^*^*' ^^ ^^^ phosphorite samples. +2 +2 It indicated the substitution,of divalent Ca by Mg in the saline, marine sea-water conditions and reflects the palaeo- salinity of the Bijawar basin. This relationship was thus respon sible for inhibiting of MgO on the apatite diagenesis in the shallower water during early stages of formation of apatites. This also reveals the rhythmic alteration of "Mg-poor-P-rich" layers in these phosphorites (Gulbrandsen, 1969; Banerjee, 1978; Walter and Hanov, 1978; Morse, 1979; Nathan and Lucas, 1981; Lucas, 1984). 413 (30) Like other major ions which are located outside the crystal lattices of apatites, the TiO^ also shows a negative correlation with Pn^s ^° ^^® study area. This relationship may be due to detrital occurrences of TiO. bearing minerals and by means of adsorption on the phosphate, iron and clay-bearing minerals (Goldschmidt, 1954; Cook, 1972). (31) In the study area/ the ratio values of CaO/PjO. against P^Oc show a progressively positive correlationship in all samples of the phosphorites. The low ratio values of Ca^O/^^^c^ further confirms the absence of stromatolites and carbonate bearing minerals like limestones and dolomites. The low values and th^ above relationship supports mild lateritization in which part of CO2 has been lost and with the presence of a huge amount of clay and iron-*bearing minerals as groundmass (McConnell, 1938; Young^ 1969; Cook, 1972; Lucas, et al.# 1980; Giresses, 1980; Saigal and Banerjee, 1987; and Banerjee and Saigal# 1988). (32) In the study area* the low values of ^^0^2^^ against ^2^5 s^<^w strong negative correlation in the phosphorite samples. From the above it could be inferred that the phospho rites were precipitated at and/near the continental margins which is very close to the Bundelkhand granitic basement. The episodes of mild weathering/leaching are also responsible for the decarbonation of apatite and gangue minerals during ancient period (Bliskovsky, 1984). 414 (33) In the study area, the higher ratio of CaO/MgO and negative correlation with ^2*^5 indicated ^n inhibitation in the precipitation*of phosphate in the marine, shallower, warm conditions by means of direct inorganic precipitation processes and through upwelling currents as suggested by earlier workers (Simpson, 1966; Martin and Hariss, 1970; Atlas, 1973; Nathan and Lucas, 1976; Breraner, 1978)• IXA. GENESIS BASED ON TRACE ELEMENT GEOCHEMISTRY : The genetic aspects of Hirapur phosphorites based on trace element distributions and their mutual relationships are discussed as follows :- (1) In the ^tudy area, the higher concentrations of uranium in all four types of phosphorite samples (particularly secondary phosphorite) may be due to more remobllization nature, and its precipitation from hexavalent (U ) to tetravalent (U ) states which is slightly reduced one. It may be possible that some part of the U* has been replaced by Ca and Al in primary and secondary phosphorites during high oxidising to slightly reducing environments. It indicates that the uranium may be present in both the u"*" and U states but unfortunately no independent uranium phosphate mineral is reported by petrological XRD studies, etc. On the other hand, the uranium in the phosphorites may be 415 present as an adsorbed and absorbed states by huge varieties of collophanes and crandallites. Iron and clay bearing minerals. The depositlonal environment might be marine, oxidizing, shallower and rate of the sedimentation on the continental border land or margins were very slow. On the other hand, episodes of weathering/ leaching of the primary ores on the on-shore environment might be responsible for the secondary enrichment of black colour uranium along with goethitic coatings in the secondary phosphorites. This type of alteration of primary ores took place generally above the Iron Formations during Early to Middle Proterozolc time all over the world (Kazakov, 1937; Dietz, et al., 1942; McKelvey, et al., 1955; McConnell, 1958; Clarke and Altschuler, 1958; Altschuler, et al.# 1958; Hab5hi, 1962; Krauskopf, 1967; Kolod.ny, and Kalpan, 1970; Spaldang and Sacket, 1972; Burnett, 1974; McArthur, 1978^a# b; Avital, et al./ 1983; Mahadevan, 1986; and Singh,1988)• (2) The vanadium content is almost low in Hirapur phosphorites and it could be due to the absence of organic matter and sulphide bearing minerals and poor supply of vanadium from source rocks.' The minor content of vanadium indicated the localized origin of phosphorites in the marine, shallower, near the continental margins which could retained/sink by clay* iron and phosphate bearing minerals during and/after the phosphatization processes (Runnels and Schleicher, 1956; Graf, 1960; Schmltt and Thiny, 1987; Proshlyakova/ et al., 1987; Banerjee and Saigal, 1988). 416 (3) Like vanadium, nickel contents are also poor in these phosphorites except in a few sanples of ironstone phosphorites. The nickel might have introduced during weathering process of primary ores* On the other hand, nickel had' adsorbed onto the surfaces of iron and clay and phosphate bearing minerals (Cook, 1972 and Howard and Hough, 1979). (4) In the study area, the Cr concentration varies into primary and secondary phosphorites. The lateritization of primary ores at a few places in the area, indicated the bi_^modal distribution of Cr which might have taken place due to weathering, erosion, re- mobilization and reprecipitation processes, etc. (Tooms, et al«/ 1969; Mohammad, et al., 1981; Reeman, 1984; Proshlyakova, et al.* 1987). (5) Like other trace elements, copper content is also low in Bijawar phosphorites and its minor amount may be due to poor +2 +2 +2 substitution of Cu by Fe and Ca in these sediments. On the ' +2 other hand, it is also possible that Cu has been adsorbed by carbonate-fluorapatite phase and its gangue constituents like iron and clay bearing minerals. The presence of copper along with uranium also indicated the marginal shelf settlement of phosphorites in the Bijawar basin (Carobbi and Pieruccini, 1947; Krauskopf, 1956; Green, 1959; Cook, 1972; Proshlyakova, et al., 1987 and Singh; 1988). 417 (6) Like copper, other trace elements namely, Co, 2n, Cd, Ga/ Pb, etc, behaves similarly in all four types of phosphorite samples. These elements may be due to minor scale substitutions t and adsorption/absorption by huge varieties of apatites, clay and iron-bearing minerals (Lit, cited), (7) In the study area« nickel behaving negatively with uranium in all phosphorite samples. It may be possible that nickel was weakly substituted/absorbed on the phosphatic gels and its gangue minerals and on the other hand, the higher uranium content has been locked up/captured by iron and phosphate contents, etc. (Debrabant and Paquet, 1975; Lucas, et al.r 1978). (8) In the study area, uranium also behaves similarly with vanadium and chromium like nickel in all phosphorite samples and further supported the diagenetic theory of phosphatic sediments (Lit. cited). (9) In the study area* uranium behaves positively with copper and lead in primary phosphorites and negatively weak in secondary phosphorites. These two different relationships of uranium with copper and lead reveals that the primary phosphorites were originated during highly oxidizing to slightly reducing marine, shallower conditions of the basin and negative correlations may be due to episodes of weathering in the secondary phosphorites (Verma, 1980; Al-Bassam, et al., 1983). 41S IX.5. GENESIS BASED ON TRACE AND MAJOR IONS GEOCHEMISTRY t The genesis based on mutual relationships between trace and major elements of Hirapur-phosphorites is discussed as follows s- (1) In the study area« ^2^5 ^^°^® ® progressively positive relationship in the phosphorite samples and it indicated that - i) both the elements have chemical coherence in the sedimentary environment; ii) the absence of organic matter« stromatolites glauconites and pyrite in the phosphorite does not favour the highly reducing environment of the basinal waters but on the other hand« it can be suggested that these sediments were finally precipitated during highly oxidizing environments; iii) precipita tion of apatite might have taken place in the low lying, stable areas where physiographic/topographic depressions, voids/cavities# synclinal folds, minor/false unconformities controlled the phos- phatization process, due to slow influx of detrital material; iv) the higher content of U3OQ among these phosphorites may be due to mild weathering of the ores ' in which the secondary enrichment is clearly responsible, whic^ took place in the ferruginated oxidizing zone (Ka^itani, 1968; Elliot, 1968; Sakanove, et al., 1968; Dar, 1970; Kolodny and Kaplan* 1970; Degens, 1972; McConnell, 1963 and 1973; McArthur, 1974 and 1980; Slansky, 1979; Banerjee, et al., 1982; Saigal and Banerjee, 1987; Kolodny, 1981). m (2) In the study area# ^o^S "^^i^^si'^®'^ a positive relationship with Ni in the sanples of primary phosphorites and a weak but negative correlation in the secondary phosphorite. It is suggested that during primary phosphatization stage, the part of the Ni has been adsorbed by huge mass of apatite, iron and clay-bearing minerals. On the other hand, a weaker negative relationship in secondary phosphorite may be due to episodes of alteration/ remobilisation processes, etc. (Cruft, 1966; Debrabant and Paquet, 1975; Lucas, et al./ 1978; Saigal and Banerjee, 1987)• (3) Besides nickelv, the other trace elements like Cd, Co, Cu, also show the similar relationships with P^^^s ^^ primary and secondary phosphorites. Thus, the above observations regarding genesis of the phosphorites further confirmed the view point as stated above, (4) In the study area# Pb correlates negatively with P^^c ^^ all phosphorite sanples and it is suggested that during marine, shallower, humid to arid and highly oxidizing conditions of the +2 +2 basin, the mutual substitution of Ca by Pb within the apatite lattice might have taken place (Rao, et al., 1978; Howard and Hough, 1979 and Viqar, 1981). (5) Besides, Pb the other trace elements naaely, Cr, V# Zn also show a negative correlation with P^^s i^ ail types of phosphorite samples and have further supported the above obser vations regarding the origin and its associations (Lit. cited). 420 (6) In the study area, a sympathetic correlation is reported in between CaO and U^O- in all phosphorite samples• It is suggested +2 +4 that the minor amount of Ca has been replaced by U which are having similar ionic radii• On the other hand, it is also possible that the greater amount of UjOg has been, adsorbed by fine grained apatites, iron and caly bearing minerals during marine, alkaline and oxidizing environment (Clarke and Altschular, 1958? Jensitn, 1958; Sheldon, 1959; Betts and Leigh, 1959; Habshi, 1962; Park Jr. and Roy, 1963; Subramanlan, 1980; Pettijohn, 1984). (7) In the study area, U^O show negative relationship with AI2O3 in primary and positively in secondary phosphorites. It may be possible that during primary phosphatization the minor substitu tion taken place in these sediments in which cellophane was the dominating apatite phase. On the other hand, the positive relation ship of AI2O3 with U3O in secondary phosphorites may be due to formation of crandallite (cal-al-phosphate) in which the part of the Ca* is replaced by Al by physical and chemical processes (Pric and Rose, 1981). (8) In the study area, the ratios of U^OQ/PJO^ shows a pro gressive positive relationship with P2^5 ^^ ^^^ phosphorite samples. It indicated that the phosphatization took place in the open, marine, oxidizing and shallower part of the basin. The interstitial waters also might have played an important role in the precipitation of apatite over an extensive area (Al-Bassam, et al., 1983). 422 CHAPTER - X SUMMARY & CONCLUSION The Hirapur-Mardeora phosphorite occurrences of Bijawar Group of Gangau Iron Formations lying over the basement of Bundelkhand Granite Complex which belong to Archean period. The megascopic, microscopic, scanning and x-ray study of the phosphatic rocks of the study area revealed that there are two distinct types of phosphorites, viz., primary and secondary. Minerelogically/ the primary phosphorites being associated with shales, ironstones and quartz-breccia are mainly composed of cellophane a c^rbonate-fluorapatite phase, whereas the secondnry phosphorites contain cran(3allite (calc-aluminium phosphate). The predominant phosphate bearing mineral usually occur in primary phosphorite as pelletal# oolitic, ovulitic, granular, crypto, micro to megacrystalline, disseminations, radiating, amorphous, recrystallized cellophane as thin veinlets* lath, nodular shaped, etc. In secondary phosphorite, the crandallite occur rrrastly as lath shaped in the pores, cavities, voids, fracture, fissure fillings, etc. It also occurs as pelletal, ovular and irregular grains. Ouartz is the most predominant mineral among the gangue constituents in both primary as well as secondary phosphorites. The other common gangue minerals are hematite. m magnetite, limonite, goethite, iron-oxide, muscovite, sericite, chlorite, kaolinite, ilmenite, rutile, chert, feldspars, etc. The phosphorite is cemented by silicious, ferruginous, phesphatic materials, etc. The sedimentary structures which are preserved in the phos phorites are primary bedding, current and cross-beddings, lamina tions, ripple marks, mud cracks, synclinal and anticlinal folds, slates and phyllites, faults, cleavages, fracture, and fissures and vein-fillings, pelletal# nodular structures, etc. The occurrences of collophane and crandallite in the four types of phosphorites indicated a-contemporary phosphatization which was controlled by physical and chemical factors. The absence of stromatolites revealed direct, inorganic, authigenic processes during early Proterozoic age which took place from tropical to arid climatic conditions. The variations in the crystallinity of collophane and crandallite further supported the above observations The phosphorites bands/layers suggested the supratidal to inter- tidal/ continental margins and borderland of the basin where precipitation was completed. The subroundness of pellets indicated the low energy environment and poor transportation. The occurrences of hematite, limonite, and iron-oxides and magnetite Indicated the highly oxidizing to reducing environment and low metamorphism. The presence of all primary and secondary sedimentary features further supported the shallower, marine, restricted shoals of 424 littoral basin of intracratonic sea which fringed the margins of the Bundelkhand Granitic Craton. The episodes of weathering in primary ores gave rise to secondary remobilised ore by dia- genetic processes in which crandalllte was formed. Total 13 major oxides namely, Po^B' CaO, CO^, HjO , AI2O3/ ^®2^3' ^^^* ^^^2' ^^2^' ^2^' ^^^' ^^°2' ^"^ "^^^^ analysed Among them the concentrations of Pp^B' ^^^ ^^'^ ^^^2 ^^® very high; Fe-O^ and AI2O3/ moderate to low and CO2/ H2O # FeO, NajO* K2O, MgO, Ti02 and MnO are very low in all four types of phos phorite samples. The P2^5 ^^^^ positive relationship with CaO, CO2/ H2O'*" and NajO; and negative with AI2O3/ KjO, Fe203, FeO, SiO^, MnO, MgO and Tio., The important inter-relationships of ^ 2 major oxides like CaO show positive correlations with ^02^ H-O and negative with SiO^, Fe202, FeO, Na20/ K2O, AI2O3, MgO and randomly with MnO. The inter^relationships of Fe202, FeO, ^^2^3' Si02, Na20 and K2O within the other oxides also show similar relationship in all phosphorite samples. The recalculated ratio values of Ca0/P2 05/ vs. ^2^5* ^^2^'^^2^5 ^^* ^2^5' ^^^^ positive but the ratios of C02/P20^ vs. P2^5 a"^ CaO/MgO vs. P^O^ nega tive in all the samples. The above critical study of the distributions and geo- chemicai correlations among the 13 major constituents of the phosphatic rocks of the study area, led the author to believe that most of the ores are in the primary state and deposited 425 syngenetically with the host rocks (shales^ ironstones and quartz-breccia) through authigenic processes. In the secondary ores that the one mostly derived from the primary ores through eustatic sea-level changes, actions of sea waves, tides, and currents and groundwater circulations, most of chemical consti tuents have the same trend of distribution and relationship as that of the primary ores. The phosphatization might have taken place in a fairly oxidizing to slightly reducing environments, supratidal to intertidal, continental margins, shallower parts of the basin, epicontinental sea shoals, tropical to arid climate, high to moderate alkaline, marine, structural and stratigraphic controls, by upwellings currents and restricted circulation of basinal waters. The foriiicition of epigenetic secondary phosphorites was mainly due to lateritizatlon as indicated by the concentration trends of each element. There are innumerable cases of absorption and/adsorption and mutual substitutions of certain minor elements out and inside the apatite lattices. The narrow and wide varia tions in the concentrations of certain elements attributed possible mild leaching of the syngenetic ores. The formation of crandallite + 2 in the epigenetic ores may be due to ionic substitutions of Ca by Al inside the apatite lattices. Total 10 trace elements namely, U, V, Ni, Cr, Cu, Co, Zn, Cd, Ga and Pb were determined in the phosphorite samples. ^-26 The concentration of uranium is very high among all above trace elements particularly in secondary ore samples. The Cu and 2n content is moderate to low and other trace elements like, V, Ni, Cr, Co, Cd, Ga, and Pb, are very low. Uranium shows positive correlation with Cu and negative with Ni, V, Or, and Pb. Vanadium also shows a negative behaviour with Cr, Ni, and Co; Ni positive with Cr, Cu, Co and Cd. However, Cd reveals a positive relation with Cu and Cr, and negative with Co in phosphorite samples. The relationship of major oxides with trace elements plotted against P^Oc shows sympathetic behaviour with U,0 and Ni and weak sympathetic with Cd, Co and Cu and antipathetic, with Pb, Cr, V, and Zn. The CaO shows a positive relation with \^2^S' ^^' ^"' ^^ ^^^ negative with V, Pb, Cd, and Cr. The other major oxides like Al^O^, MnO, CO2/ "20"^, Fe^O^, NajO, KjO, SlOj and MgO also behaves similarly as P2^5 ®"^ ^^^ with trace elements. The ratios values of ^2^0/^7^5 ^^^^ ^2^5' ^3^8/^®2°3 ^^^^ ^2°5/^®2^3 ^^^^ positive and U30g/Fe20^ vs. ^^^203 and V/P20^ vs. P2 05^ '^'^/^z^^B ^^ * ^2^5 ^"°^ ^^/^^2°3 vs. AI2O2 a negative relation in all the phosphorite samples. The above distributions and inter:^relationships of trace elements and trace with major oxides and their ratios in primary and secondary phosphorite samples reveal that these elements were precipitated by direct, inorganic, syngenetic, and authigenlc processes in the primary ores and by epigenetic. 427 leaching, remobilization and reprecipitation in the cavities, voids, fracture and fissure fillings in the secondary ores during diagenetic processes. These processes might have taken place during slightly reducing environment under tropical to arid climate and in shallower parts of the basin. It may be possible that some parts of the trace metals might have been absorbed/adsorbed in the groundmass of gangue minerals and partly replaced within the apatite lattices. The random distri bution and correlation may also be due to several episodes of weathering processes. The Hirapur phosphorites are classified on the basis of *.- origin, sedimentary processes, alteration, commercial grade, presence of P2^5 content, CaO/MgO ratios, Na20/K20 ratios, SiOj, CaO + MgO, Po^S weight percentages as-sedimentary; authi- genic, orthochemicals, allochemical and metachemicals; non- altered and .atered; acid, furnace and beneficiation grades; phosphorites^ ancient; highly alkaline and moderately alkaline; phosphatic silicanite and phosphatic dolomitic-limestone groups, etc. On the basis of individual weight percentage of TiO^ vs. ratios of total Iron/MgO; TiOj - KjO - PjOc' TiO - MnO - ^2^5' ^•*-2°3 " "^otal Iron - SiO^; SiO^ - AI2O3 - K2O and CaO - ^®2^3 " '^•^2^3 ^^^i^rams reveal that the main source of the m Hirapur phosphorites is adjoining Bundelkhand Granite Complex which is the basement of the BiJawar basin. Besides, the other sources may be host rocks of Bijawar Group, local active rivers and their major tributaries and to some extent sea-basinal waters. 129 LITERATURE CITED A " SERIES Aggrawal, K.C and Subramanyan^ N^N. (1986) - Enrichment of ores and minerals. India's Environment. G.S.I. Memoir NO. 5, pp. 125-137. Al-Bassam, K.S. et al. (1983) - Can^Janian-Maastrichtian phospho rites of Iraq. Petrology, Geochemistry and Genesis. Min. Deposita, 18, pp. 215-233. Alder, H.H. et al. (1963) - Infra-red absorption frequency trends for anhydrous normal carbonates. Amer. Min., vol. 48, pp. 124-137. Alder, H.H. (1970) - Interpretation of color relations in sand stones as a guide to Uranium Exploration and ore-genesis. IAEA. Vienna Report, pp. 331. Ali# K.N. et al. (1981-82) - Mineral Investigation report of Sagar district (M.P.), Rec. G^s.I., vol. 116, part 1, pp. 58. Altschuler, Z.S. et al. (1952) . X-ray evidence of the nature of carbonate apatide (Abstract). Bull. Geol. Soc. Amer., vol. 63, pp. 1230-1231. (1953) - X-ray evidence of the nature of carbonate- apatide. Amer. Mineralo., vol^ 38, pp. 328. (1956) - the aluminium phosphate zone of the Bone valley formation of Florida and its uranium deposits. XJ^S^GmS* Prof. Paper, 300, pp, 495-504^ (1958) - GeochemlstJry of Uranium in apatide and phosphorites - U.S.G.C. Prof. Paper, 314-D, pp. 45-90. (1959) - Petrography of phosphorites. In Geology of Isla Mona Puerto Rico and not^s on age of Mona Passage (Ed. C.A. Kaye). U.S.G.S. Prof. Paper, 5l7-C, pp. 157-167. (1967) - Rare-Karth^ elements in phosphorites geo chemistry and potential recovery. U.S.G.S. Prof. Paper, 575-B, pp. B-1 - B-9. ^JO (1973) - The weathering of phosphate deposits - geochemical and enviroranental aspects in Girifflth, K,J,; Beetori/ A*; Spencer, J*M. and Mitchel, D,T.; editions. Environmental phosphate hand book, John Wiley & Sons, CH-III/ pp. 35-96. (1980) - The geochemistry of trace elements in marine phosphorites s Part-I characteristic abundance and enrichment. In : Y,K. Bentor (Edition). S.B,P.M. Spl. Publ. No. 29, pp. 19-30. Ames, LiL» (1959) - The genesis of carbonate-apatites. Eco. Geol., vol. 54, no. 5, pp. 829-841, ___^ (1959) - Quoted from Norway Blate et al. •Origin of Sed. Rocks, pp. 55. Andrews, J.C. (19§3) * Water masses nutrient levels and seasonal drift on the outer Central Queensland shelf (Great Barrier Reef). Aust. Jr. Mar. Fresh Water. Res. 34, pp. 821-834. Armstrong, F.A.J. (1965) - Phosphorus in Riley, J.P. and Skirrow, G.; eds. Chemical Oceanography, vol. 1, N#Y. Academic Press, pp. 323-364. Atlas, E.L. (1975) - Phosphate equilibria in sea water and inter stitial waters. Ph.D. Thesis, 1975, Oregon State Univ. Dlsser. Abs. Internet., vol. 36, no. 7, pp. B-3285. ^^_^^___^^^^ (1975) - Phosphate equilibria in sea water and inters- titial waters. Ph.D. Thesis, Oregon State Univ. Corvallis, Oreg., pp. 154, and Pytkowiez, R.M. (1977) - Solubility iDehaviour ot apatites in sea water - Limnol. Oceanography, 22, pp. 290^300. ______(1979) - Soluoility controls of carbonate-fluorapatite in sea water. Rept. on Marine Phosphatic Sed. Workshop, Hawaii, pp. 65 (Eds.) Burnett, W.C. and Sheldon, R.P., pp. 18.20. Auden, J.B. (19 33) - Vindhyan sedimentation in the Son valley. Mem. Geol. Surv. India, vol. 62, pt. 2, pp. 141-250. Avital, Y. et al. (1983) - Uranium-Geochemistry and Fission-Trace mapping of phosphorites. 5Sefa field, Israil. Eco. Geol., vol. 78, no. 1, pp. 121-131. Awasthi, N. (1970) - Some aspects of the Krol Formation of the Himalaya, Xndia contri. Mineral. Petrol., 28, pp. 192-220. 43t Axelrod^ S. et al, (1980) - The petrography of Israil phsophorites as related to the beneficiatlon. S.E.P.M. Spl* Publ. no. 29, pp. 153.-166. and Rohrlick, V. (1982) - Chemical variability in francolites from Israil phosphorites macrorganisms, Min. Deposita* 17, pp. 1-15. B ^ SERIES Bachra/ B.N. et al. (1965) - Precipitation of calcium carbonates-Ill the effects of sDagnesium and fluoride ions on the spontaneous precipitation of cal-carbonate and phopshates. Arch. Oral. Biol./ vol. 10, pp. 731-738. Ball, V. (1881) - The Geology of Maubhum and Singhbhura. Mem. XVIII (2) (quoted in Dunn's Mem. G.S.I./ vol. LXIX(2), pp. 290), Bandyopadhyay/ B.K# and Roy, A# (1987) - Geochemistry and environ mental significance of banded garnet amphibole rock (B.G.A.) around Naurhiya* Bigawan Group in Sldhi district (M«P.). Jr. G.S.I., vol. 30, no. 2, pp. 143-151. Banerjee, A.K. and Singh, H.J.M. (1981) - Palaeogeography and sedimentation of Vindhyans in eastern Rajasthan. Misc. Publ. G.S.I. No. 50, pp. 89-94. Banerjee, D.M. (1971^ a) - Origin of Precambrian sedimentary phosphorites of Rajasthan, India Proceed. 58th Indian Sci. Congr. Pt. Ill, Sector V, pp. 297. (1971,b) - Aravalli stromatolites from Udalpur, Rajasthah. Jr. G.S.I. 12, (4), pp. 349-355. (1971) - Precambrian stroraatolltic phosphorites of Udaipur, Rajasthan, India. Bull. Geol. Soc. Amer. 82, pp. 2319-2330, (1974) - Microfosslls from the Late Precambrian phos- phoritic stromatolltlc of Udaipur, Rajasthan, India in Recent Res. in Geology, vol. 1, pp. 26 3-268. 32 ^ (1978 a) - Chemical rhythmlcity in the Precambrian laminated phospnatic stromatolites and its bearing on the origin of algal phosphorites• Indian Jr. Earth Sci. 5(1), pp, 102-110. (1978 b) - Study of primary layers phosphorites depo- sitionai basin of India. In : P.J, Cook and J»H. Shergold (Eds.), Proterozoic-Carabrian phosphorites, A#N.U. Press Canberra, pp. 34-35. (1980) - Trends of Precambrian banded iron-ores and phosphatic provinces relation to the premitive crust : Proc. Fertilizer Raw Material Res. Workshop (August, 1979) . E.w. Centrie Holalu Hawaii Eds- Sheldon, R.P. and Burnett, W.C., pp. 225-236. and Basu, P«C. (1980) - Stromatolites in the Jhabua phosphorite-lithostr., age and palaeo-environraent, G.S.I, Misc. Pub. No. 44, pp. 240-254. et al. (1980^ a) - Petrology, mineralogy, geochemistry and origin of the Precambrian Aravalli phosphorites deposits of Udaipur and Jhabua, India. Eco. Geol., vol. 75 (8), pp. 1181-1199. and saigal, G. (1980^ b) - Major element geochemistry of some Precambrian stromatolitic phosphorites and associated base metal rich rocks in a part of Udaipur district, Rajasthan, India (Abst.), Intern. Field Workshop of Intern. Geol. Correl. Progr. Proj.- 156, 3rd Ullan Bator, June, 1980, Proceedings, pp. 19-20. ______^_^ (1981) - Apatite crystallites size of Precambrian phosphorites of India, Eco. Geol.(in press). ___^^^____^ (1982) - Lithotectonic phosphate mineralization and regional correlation of Bijawar Group of rocks in the Central India. In s Geology of the Vindhyanchal, Valdiya, K,S. (Ed.) Hindustan PAibl. Corp., Delhi, pp. 19-54. et al. (1982) - Precambrian phosphorites in the Bijawar rocks of Hirapur-Bassia areas, Sagar district, M.P., India. Min. Deposita, 17, pp. 349-362. et al. (1984) - Element variation pattern in the Pre cambrian phsophorites and county rocks of Udaipur, Rajasthan, G.S.I., Spl. Pub. no. 17, pp. 63-78. and Saigal, N. (1984) - Proterozoic phosphorites of India. Mem. No. 6, Geol. Soc. India. Seminar on Purana Basins of India, held at Hyderabad, pp. 471. 433 _^__^^_^^^_^ (1985) - Petrozoic stratigraphy of the Indian Platform and the concept of phosphogenic cycles - A proposal Bull. Geol* Surv. of Finland, vol* 331, pp. 73-89. et al. (1986) - Genesis of Upper Proterozoic - Cambrian phosphorite deposits of India s Isotopic inferences from carbonate-fluorapatite, carbonate and organic carbon. Precambrian Res., vol. 33, no. 1-3, Sept. 1986, pp. 239-253. __^^ (1987) - Environmental impact of phosphate mining in India. Jour. G.S.I., vol. 30, no. 5, pp. 439-450. (1988) - Diagenetic bedding,(Lecture notes in Earth Sciences, no. 6) by *- Werner Rickeci 1986, Springer-Verlag, Berlin, Heidelberg, N.T., pp. 210 (Book Review), Jour. G.S.I., vol. 32, no. 2, pp. 149-151. Basu, P.M. (1984) - Stratabound phosphate deposit and its relati<»: to copper mineralisation in Singhbhum Belt, Bihar, G.S.I. Sp. Pub< no. 17, pp. 173-178. Basu, A.K. (1986) - Geology of parts of the Bundellchand Granite Massif of Central India. Rec. G.S..I. vol. 117, pt. 2, pp. 61-124. Baturin, G.N. (1969) - Authigenic phosphate concretions in recent sediments of the S.W. Africah Shelf. Dok. Akad. Nank. S.S.S.R. Earth Sci. Sec. 189, pp. 227-230. et al. (1970) - Phosphorite formation on the shelf off S.W. Africa. Litol. Polezu Is Kop., vol. 3, pp. 266-276. (1971) - Recent authxgenic phosptiorite formation on the S.W. African Shelf in Uelancy. P.M. Geol. Sci. Rept. 70/16, pp. 91-97. (1971) - Ttie stages of phosphorite formation on the ocean floor. Nature, Physical Sci., vol. 232, no. 29, pp. 61-62. ^^__^____ (1971) - Formation of phosphate sediments and water dyhamics. Oceanology, vol. II, pp. 373-376. (1972) - Fosfor V Ilovykh Vodakh Osadkov Yugo - Vosto- chnoi Atlantiki (phosphorus in pore waters of sediments in the S.E. Atlantic) s Oceanologiya, 1972, no. 6, pp. 1020-1027 (In Russian)• et al. (1972) - Radiometric evidence for Recent Formation of phosphatic nodules in marine shelf sediments Marine Geol., vol. 13, no. 3, pp. M-37 - M-41. 134 et al« (1972) - Rare ^arths in phosphorites samples from the ocean floor. Dokl. Acad. Sci»/ U.S.S.R,, 207, pp. 208_210. (1978) - Phosphorites on the ocean floor. P.P. Shirshow Inst. Oceanol. Acad. Sci., U#S.S*R./ Moscow. Nauka Press Moscow, pp. 232 (In Russian). (1979) - Phosphorites on the sea floor and their origin. Marine Geol«/ vol. 31, no, 3, pp« 5-13. (1981) - Phosphorites on the sea floor. Origin, composi tion and distribution. Elsvier Sci. Pub. Comp., N,Y., pp. 343. Beach, A. and Fyfe, w.S. {1972) • Fluid transport and shea-r zones at Scourie, Sutherland : Evidence of over thrusting. Contr. Min. Petrol., vol. 36, pp. 175-180. Benmore, R#A* et al. (1984) - Stable isotope con5)osition of structural carbonate in sedimentary francolite. G.S.I. Spl. Publ. no. 17, pp. 35-40. Bentor, Y.K. (1980) - Phosphorites - The unsolved problems. In s Y.K. Bentor (Ed.) • Marine Phosphorites. SEPM. Sp. Publ. no. 29, pp. 1-18. Berg, J.W. (1972) - Physical and chemical factors in the formation of marine apatites. Eco. Geol., vol. 67, no. 8, pp. 824-827. Berzina, I.G. et ^1. (1978) - Boron and Uranium distribution in concretionary phosphorite of the Aktyubinsk basin. Dokl., vol. 242, pp. 159. Betekhtin, A. (1959) - Phosphates. A course of Mineralogy, pp. 399-418. Betts, R.H. and Leigh, R.M. (1950) - Ionic species of tetravalent uranium in Rerechloric acid and sulphuric acids. Canad. Jour. Res., vol. 28(8), pp. 514-525. Bhattacharjii, S. (1972) - Basal conglomerates of the Semri series. Son valley, M.P. The Q. Jour, of the G.M. & M.S. of India, vol. 44, no. 3, pp, 139. Bhattacharya A.K. and Sengupta, H.P. (1984) - Depositional environment of phosphate associated with cherty stromatolitic dolostone of the Dhari Member (Gangolihat Dolomite Formation). Pithoragarh district, U.P.^ G.S.I, sp. pub. no. 17, pp. 159-172. 435 Birch, G«F. (1973) - Unconsolidated sediments off the Cape West Coast s Joint Geol. Surv, Univ. of Cape Town, Marine Geol, Programme, Tech. Rept., 5, pp. 48-67. (1975) - Sediments on the continental margins off the West Coast of s. Africa. Unpubl. Ph*D. Thesis, Univ. Cape Town, pp. 210. (1977^ a) - Phosphorites from the Saldhana Bay region of S. Africa. Roy. Soc. South Africa, 42, pp. 223-240. (1979. a) - The nature and origin of mixed glauconite/ apatite pellets from the continental margin off s, Africa, Mar. Geol., vol. 29, pp. 313-334. ^^_^^^^^_^ (1979, b) - Phosphatic rocks on the western margin of S. Africa. Jour, of Sed. Petrol., vol. 49, no. 1, pp. 93-110. ^^^^__^^_^ (1980) - A model of penecontempory phosphatization by diagenetic and authigenic mechanisms from the western margin of S, Africa. SEPM Spl. Pub. no. 29, pp. 79-100. Blackwelder* E. (1916) - Geological transformations of phosphorus. Geol. Soc. Amer. Bull* 27, pp. 47 (Abst.). ^^^^_^^^ (1916) - Tlie Geological note of phosphorus. ;^ner. Jour. Sci. Series 4, vol. 42, pp. 288-298. (1926) - Phosphate deposits of the Pacific. Eco. Geol. vol. 20, no% 7, pp. 698. BlisJcovskiy, V.2. et al« (1967) - The strontium content of phosphorites. Geochem. Inter, vol. 4, pp. 1186-1190. (1969) - Geokhiaiya s Osobennosti Kontsewtratsii elementov - primesey V fosforitakh (The geochemistry and characteristics of the concentration of trace elements in phosphorites : Ph.D. Thesis), IMGRS, Moscow, pp. 239. . et al. (1969^a) - Accessory Lanthanide in phosphorites. Geokhimiya, no. 11, pp. 102. et al. (1969,b) - On the composition of lanthanides in phosphorites. Dokl. Akad. Nauk. S.S.S.R., 186 (4), pp. 230-233. ^__ et al; (1978) - Sulfur Isotopic composition of the minerals of phosphorites s Geochemistry Inter, vol. 8, pp. 148-155. m Borchert, H. (1960) - Genesis of marine sedimentary iron ores. Trans. Min. Met,, vol. 69, pp, 261-279, Borneman-Starynkevich, I*D. and Belov, N.V. (1940) - Isomorphic substitutions in carbonate-apatite j C.R. AC Sci., U.S.S.R., vol. 26, pp. 804-806. (1953) - Carbonate-apatites. Akad. Nauk., S.S.S^R. Dokl. vol. 90, pp. 89-92. Bortleson, G.C. and Fred Lee, G, (1974) - Phosphorus, iron, and manganese distribution in sediment cores of six Wisconsin Lake, Limn, and Oceans, 19, pp. 794-801. Boyle, R^G. (1984) - Elemental association in mineral deposits and indicator elements of interest in geological prospecting* Geol. Surv.of Canada/ Dept. of Energy Mines and Resources, Ottawa, pp. 1-40. Bray# J.T. et al. (1973) - Phosphate in Interstitial water of anoxic sediments s Oxidation effects during samples procedure, Sci. vol. 180, pp. 1362-1364. , Bremner, J.M. (1975) - Faecal pellets, glauconite, phosphorite and bed rock from the Kunene-Walvis continental margin s GSOJUCT Mar. Geol. Prog. Tech. Tept. Geol. Dept., Univ. of Cape Town, vol. 7, pp. 59-68• (1978) - sediments on the continental margin off S-W Africa between Sylvia Hill and the Kunena River. Unpubl. Ph.P. Thesis, Univ. Cape Town, pp.310. Burnett, W.C. (1973) - Inorganic apatite foinmation on the continen tal margins of Peru and Chile. Abs. Ann, Meet. Amer. Assoc, of petrol. Geologists, pp. 17. (1974) - Phosphate deposits from the sea floor off Peru and Chile. Radiochemical and geochemical investigation concerning their origin. Hawaii Inst. Geophys. Rep. 74-3, pp. 164. ___^ and Gomberg, D.N. (1977) - Uranium oxidation and probable subaerial weathering of phosphatized limestone from Pourtales terrace. Sedimentology, vol. 24, no. 2, pp, 291-302. (1977) - Geochemistry and origin of phosphorite deposits from the off - Peru and Chile. Bull. Geol. Soc. of America, vol. 88, pp. 813-823. 437 and Vech, H.H« (1977) - Uranium series disequilibrium studies in phosphorite nodules from the west coast of $• America Geochem. et. Cosm. Acta, vol, 41, pp» 755-764. and Sheldon, R.P. (Eds.) (1979) - Report of the marine phosphatic sediments workshop Honolulu, Hawaii, E-w Center, Resources system Instt,, pp. 57-65• et al. (1980) - Uranium series, oceanographic and sedimentary evidence in support of Recent Formation of phos phorite nodules off Peru. SEPM sp. pub. no, 29, pp. 61-72. Bushlnski, G.I. (1935) - Structure and origin of phosphorites of the U.S.S.R. Jour. Sed. Petr. vol. 51, pp. 81-92. _^__ (1964) - On the shallow water origin of phosphorite sediments in stratum bound deltaic and shallow marine deposits. In : Develp. in Sedimentology, vol. 1, Elsevier Publ. Cc»np. Amsterdam, pp. 62-70. (1966) - The origin of marine phosphorites s Lithology and Mineral Res., vol. 3, no. 3, pp. 292-311. (1966) - Ancient phosphorites of Asia and their origin. Moscow, Nauka, pp. 192. (1969) - Old phosphorites of Asia and their genesis Israel. Prog. Sci. Trans. Jerusalem, vol. 149, pp. 266. C - SERIES Calvert, S.E. (1976) - The mineralogy and geochemistry of near- shore sediments. Chemical Oceanogr. Ed. Riley and Chester, vol. 6, ACad. Press, pp. 187-280, Canpbell, c. et al. (1952) - Report on the radioactive mineral deposits of the west Valley, Sukulu, Uganda* Great Britain Geol, Surv. Atomxc Energy, Div. Rept, 127. Cameron, F.K. and Hurst, L.A. (1904) - Action of water and saline solutions upon certain slightly soluble phosphate. Jour. Amer. Chem. Soc, vol. 26, pp. 855. Caroszi, A.V. (I960) - Microscopic sedimentary petrography, John Wiley and Sons, printed N.Y. and Lond, pp. 373-485. 43 Cathcart, J.B. (1968 a) - Florida type phosphate deposits of the United States s Origin and techniques for prospecting. In s Seminar on sources of minerals Raw materials for the Fert. Indust. in Asia and the Far East Proc. UN. ECAPE, Miner. Res. ^ev, Ser. 32, pp. 178-186. (1968, b) - Phosphate in the Atlantic and Gulf Coastal plains. In s Proc. Fourth Forum of Geol. of Ind. Mineral s Ed L»F. Brown Jr. Australia, Univ. Texas Press, pp. 23-24. Cayeux, M.Ii. (1934) - The phosphatic nodules of the Agulhar Bank s Ann. S. Africa Mus., vol. 31, pp. 105-136. Chakrabati, C. et al. (1973) - Phosphorites in the Kopill Formatioi of the Shillong Plateau. Ind. Min., vol. 27, no. 2, pp. 219-230. Chatterjii, P.K. (1941) ^ Mineral Investigations by Geol. Surv. India during Pleld-Season 1941-42, pp. 1-11. Chaudhri, R.S. and Gupta, G.D. (1977) - Petrography and genesis of Nahan phosphorites, H.P., N^w* Himalayas, Jour. Geol. Soc. India, vol. 18, no. 10, pp. 570-575. Cheney, T.M. and Sheldon, R.P. (1959) - Permian stratigraphy and oil potential, Wyoming and Utah. Intermount. Assoc. Fetr. Geol. Guide Book, 10th Anniv. Field Congr., pp. 90-100. Chj^ve, K.E. (1954) - Aspects of Biochemistry of magnesium and calcareous marine organisms. Jour. Geol., vol. 74, pp. 266-283. Chiilinger, G.V. (1956) - Relationship between CaO/MgO ratio and geologic age. Bull. Amer. Assoc. Petrol. Geol., vol. 40, pp. 390-394. et al. (1967) - Carbonate Rocks, pp. 1-50, Chiplankar, L. and Chlbbe, N. (1952) - Petrology of Granites of Bundelkhand area, pp. 1-60. Choudhuri, R. et al. (1980,b) - Stromatolites as a parameters in grade control of Jhamarkotra phosphorites. Proc; Workshop of Stromat. Jan,, 1978, Udaipur, Rajasthan, India, G.S.I., Miscl. Publ. 44, pp. 330-339. Chou, L. and Wollast, R. (1984) - Study of the weathering of alblte at room temperature and pressure with a fluidized-bed reactor. Geochim. et. Cosm. Acta, 48, pp. 2207-2217. m Chow, T.J, and M^ntyla/ A.W. (1965) - Inorganic nutrient anions in deep ocean waters s Nature, vol. 206, pp, 383-385. Clarke, F.W. and Washington, H*S, (1924) - The composition of the earth's crust, U«S«G«S. Prof. Paper, 124, pp. 117. Clarke, R.S. Jr. and Altschuler, Z.S. (1958) -Determination of the oxidation state of Uranium in apatite and phostihorite deposits Geochim et Cosm. Acta# vol. 13, pp. 127-142. Cobbold, P.R. et al« (1971) - Development of internal structure in deformed anisotropic rocks. Tectonophysics, vol. 12, pp. 23-53. Cobbold, P.R. (1977^ a) - Description and origin of banded defor mation structure s I Regional strain, local perturbations and deformation bands. Can. Jour. Er. Sci., vol. 14(8), pp. 1721-1731 (1977,b) - Description and origin of banded deformation structures i II Rheology and growth of banded perturbation. Can Jour. Er. Sci., vol. 14(1), pp. 2510-2523. Coish, R.A.# et al. (1985) - Early rift history of the Proto- Atlantic Ocean. Geochemical evidence from metavolcanic rocks in Venaont. Amer. Jour. Sci., vol. 285, pp. 351-378. (1986) - Metavolcanic rocks from the Stowe Formation, Vtermont s Remnants of ridge and interplate volcanism in the lapetus Ocean. Amer. Jour. Er. Sci., vol. 286, pp. 1-28. Collet, L.w. (1905) - Les concretions phosphates de I^Agulhas- Bank : Proc. Royal Soc. Edin., vol. 25, pp. 826-893. Cook, P.J. (J,972) - Petrology and geochemistry of the phosphate deposits of !t^W. Queensland, Australia. Eco. Geol. 67, no. 8, pp. 1193-1213. .,^^.^_^ (1976.b) - Sedimentary phosphate deposits. In : Handbook of strata bound and stratiform ore deposits s K.H. WOlf. Amesterdan, Elsvier, N.Y. Pub. Co., vol. 7(ll), pp. 505-535. ___^_^ and Shergold, j.H. (1978) - Phosphate deposits of the world (Proter. and Camb. phosphorites. Cambridge Univ. Press), vol. 1, pp. 290 (News Letter, I.G.C.P., 159, 1978). and Shergold, J.H. (1979) - Proterozoic-Cambrian phosphorites Canberra. Canberra Publ. and Print., pp. 208. _^____^__^ and Shergold, j.H. (1979) - A re-evaluation of the spatial and temporal distribution of sedimentary phosphate deposits in the light of plate-tectonics. Eco. Geol., vol. 74, no. 2, pp. 315-330. 440 and Shargold, J.H. (1983) - Phosphate study progress i Geotimes, Sept., pp. 14-15» (1987) - Sea level changes, environments, tectonics, marine resources and phosphorites. Inter-govt. Oceanogr. Comm. Rept. of governing and major subsidiary bodies* I4th session of the Assembly, Paris, 17th March to 1st April, 1987, Annex, V. Cossa, N. (1878) - "Sur La diffusion du Cerium, du lanthane et du didyme*, extract of a letter from Cossa to Sella presented by Freny : C.R. Ac. Sci., Paris, vol. 87, pp. 378-388. Coulthard, s. (1833) - Geological rapid traverses in the Sagar district (M.P,), Asiatic Researches, vol. XVIII, part 1, pp* 47. Crawford, A.R. (1970) - The Precambrian geochronology of Rajasthar and Bundelkhand, N. India, Canad. Jour. Earth Sci., 7(1), pp. 91-110. and Compston, W. (1970) - The age of the Vindhyan system of Peninsular, India. Q. Jour. Geol. Soc. London, vol. 125, pp. 351-371. Cressman, E*R. and Swanson, A.W. (1964) - Stratigraphy and petrology of the Permian rocks of the s^lfli* Montana : U*S.G^S» Prof. Paper 317-C, pp. 275-569. Cronan, D.s. (1969) - Average abundances of Mn, Fe, Ni, Co, Cu, Pb# Mo, U, Cr, Ti and P in Pacific plagic clays. Geochim. et. Cosm. Acta, vol. 33, pp. 1562-1565. Cruft, E.F. (1965) - Chemical analysis and the stoichiometiry of apatite. Geochem. et. Cosm. Acta, vol. 29, pp. 581-597. (1966) - Minor elements in igneous and metamorphic apatites. Geochem. et. Cosm. Acta, vol. 30, pp. 375-379. Cullen, D.J. (1978,a) - The distribution of submarine phosphorite deposits on the Central Chatham Rise, east of New Zealand s N.2. Oceanographic Instt., Oceanogr. Field Report, vol. 12, pp. 24-29. (1978^b) - The uranium content of submarine phosphorite and glauconite deposits on Chatham Rise of New Zealand s Marine Geology, vol. 28, pp. M-67 - M-76. 441 D - SERIES Dahanayate, K. and Subasinghe, S»M,N*D. (1990) - Formation of phosphatic coated grains and peloids by grain diminution of Precambrian apatite crystals. Jour. G.S.I., vol. 35, no. 2, pp. 189-197. Doipa, E.s. and Ford, W.E. (1962) - A textbook of Mineralogy, pp. 295. D'AngleJan, B.F. (1967) - Origin of marine phosphorites off Baja California, Mexico, Marine Geology, vol. 5, no. 1-6, pp. 15-44. (1968) - Phosphate diagenesis of carbonate sediments as a mode of in situ formation of marine phosphorites : Observations in a core from the Eastern Pacific. Canad. Jour. Ear. Sci., vol. 5, no. 1-3, pp. 81-87. Dar, K^K» (1970) - Prospects of utilizing Indian phosphorites as a source of uranium. Ind. Nat. Sci. Acad., vol. 36, no. A-6, pp. 351-359. Davidson, C.F. and Atkins, D. (1953) - On the occurrences of uranium in phosphate rock. C.R. 19th Int. Geol. Congr. Algiers, 1952, sec. XI, Fase, XI, pp. 12-31. Davy, R. (1983) - A contribution to the chemical comparison of Precambrian Iron formation* In s A.P. Trendell and A.C. Morris (Eds.) : Iron Formations, Facts and Problem, Ebevier, pp. 325- 343. Dayal, B. et al. (1984) - Phosphorite occurrences in Delhi Super-^ group, N.S. Rajasthan. G.S.I. Sp. Pub. No. 17, pp. 129-134. Debrabaut, P. and Pacquet/ J. (1975) - L'association glauconites phosphate-carbonate (Albien de La Sierra de Esfuna, Espague mendionali). Chem. Geol., vol. 15, pp. 61-75. cAe Decker, A.H.B. (1970^3) - Notes on the oxygen-depleted sub surface current off the west Coast of S. Africa. Invert. Rept. Div. Fish Africa, vol. 84, pp. 1-24. (1970^b) - An oxygen depleted sub-surface current off the west coast of S. Africa. Invert. Rept. Sea Fish, Div. S.Africa vol. 84, pp. 31-34. Deer, W.A. et al. (1962 and 1965) - Rock Forming Minerals - Non- silicates, vol. 5, Longmans, Edit, London, pp* 363-371. m Degens, E.T- (1965) - Phosphates* In s Geochemistry of sediments (A brief survey). Prentice Hall, Engle Wpodcllffs, N.J. 342, pp. 141-148. (1972) - Geochemistry of ancient sediments. In s Encyclopedia of Geochem. and Environ* Science (Ed.)« Falrbrldge, R.W., pp. 417-428. de Keyser, P. (1969 a) - The phosphate bearing Cambrian Formations of the Lawn Hl^ll ana Lady Annie, districts N.W. Queensland, Australia Bur. Mln. Resour. Rec, 1969/147 (unpub.) pp. 35. . (1969^ b) - On the genesis of the Georglna Basin phosphorites# N.W. Queensland. Bur, Mln. Resour. Geology, Geophys. Rec. 1969/79 (unpub.) pp. 20. ^__^^___ and Cook, P.J. (1972) - The geology of the Middle Cambrlan~phsophorltes and associated sediments of N.W. Queensland, Dept. of Nat. 2>ev. Bur. Miner. Res. Geol. Geophys. Bull., 138, pp. 79. D'£lla« C.P., et al.» (1981) - Nitrate rich ground water Inputs to Discovery Bay# Jamalcas A significant source of north to local coral reef. Ball* Mar. Scl,, 31, pp. 903-910. Dhoundlal^ D«P# (1987) - Inaugural address at the workshop on *Purana Basins of Peninsular Indla« Hyderabad-16', 29th Dec, 1984^ pp. 1-4. Dletz, R.S, et al« (1942) - Phosphate deposits on the sea floor off southern California, Bull. Geol. Soc. Amer. no. Si, pp, 815-84( Dingle, R.V. (1974) - Agulhas Bank phosphorites - A rev. of 100 years of Investigations, Geol. Soc. S, Afrlca# Trans., vol. 77, pp. 261-264, Donnelly, T,W. and Merlll, L* (1977) - The scavenging of magneslcun and other chemical species by biogenic opaline deep sea sediments, Chem, Geol.# vol, 19, pp, 167-186, Doyle, L.J. et al, (1978) - Recent biogenic phosphorite - Concentrations In Molblsk kidney. Scl., vol, 199, pp. 1431-1433. Dubey, V.S. (1950) - Classifications of Bljawars. Current Science, 19, pp. 143. Duey, K.C, (1952) - Geology of the area In and around Heerapur, In the Banda Tehsll, Sagar district (M«P«)« pp. 15-25. 443 Dubey, R.R, and Parthasarthy, A. (1972-) - Mlneralogical studies of phosphorites from Mussoorie, U.P. Recent Res. in Geology, 2, pp. 289-295. Du Toit, A.L. (1917) - Report on the phosphates of Saldhana Bay S. Africa. Geol. Surv. Mem./ vol. 10, pp. 1-38. £ « SERIES Elliot, H. (1968) • Uranium mineralization in the Burrow mountains ^ !9ew Mexico. Bco. Geol. and the Bull, of the Sec. of Eco. Geologists vol. 63, pp. 239. Emelyanov, E.M. and Senin, Y*M. (1969) - Peculiarities in the material composition of sediments on the shelf of S-W Africa. Litho and Mln. Resour. No. 2, pp. 10.25. Emery, K.O., et al. (1955) - Nutrient budgets in the Ocean* in Essays in the natural sciences in Honor of Captain Allen Hancock, U.S.C., pp. 299-309. ^_^_^_^^^^ and Uchupi, E. (1972) - Western-North Atlantic Ocean. Topography roc}cs# structure, water, life and sediments. Amer. ASSOC Petrol. Geologists, Mem. 17, pp. 532. Eraigh, G.D. (1958) - Petrography, mineralogy and origin of phosphate pellets in the Phosphoria Formation. Idaho Bur. Mines Geology Pamph. vol. 114, pp. 60. Engel, G. et al. (1975) - Mischkristall bildung und Kationenordnun in system Bleihy droxylapatlt-calciuro-hydroxyl apatit. Jour, of Solid State Chemistry, 15, pp. 117-126. Eriksson, K.A* and Truswell, j«F« (1974) - Tidal flat associations from a Lr. Proterozoic carbonate sequence in S. Africa. Sedimento* logy, 21, pp. 293-309. Espenshade, G.H« and Spencer, C.W. (1963) - Geology of phosphate deposits of N. Peninsular Florida. Geol, Surv. Bull. NO. 1118, pp. 1015-1021. Estep, P.A. (1973) - Infra-red micro-analysis for deducing,the formation history of ferromanganese nodules. Inter. Univ. Prog, of Research on Ferroman. deposits of oceans-floor,Phase-l, Rept. 4, sponsored by SAP, IDOE, NSF, Washington, D.C., pp. 45-75. 44 Everest, R.R, (1833) - Route survey from Mirzapur to Sagar districts (U.P, and M.P.) India (Unpub.), Report G.S.I., pp. 1-3. Ewers, W#E. (1980) - Chemical conditions for the precipitation of Banded Iron Formations. In s P.A. Trudingov, M.R. Walter and B.J. Ralph (Eds.) * Biochemistry of Ancient and Modern environments, Austral* Acad, of Sci., Canberra, pp. 83«92. (1983) - Chemical factors in the deposit and diagenesis of B.I,P. In s A.F. Trendall and R.c. Morris (Eds.). B.I.P. Pacts and Problems, Elsevier, Amsterdam, pp. 491*512. P - SERIES Permor, L,L. (1909 and 1911) - Geology of Bijawar Rocks. G.S.I., vol. XXXVII; XV, pp. 1-5 and 35-42. Pisher, 0. (1973) - On the phosphatic nodules of the Cretaceous rock of Cambrigeshire. Geol. Soc. London, Q. Jour., vol. 29, pp. 52-63. Pischer, A.G. and Arthur, M.A. (1977) - Secular variations in the pelagic realm. Soc. Eco. Palaeont and Mineralogy spec. pub. no. 25, pp. 19-50. Fleming, P.J.G. (1977) - Faunas, lithologies and the origin of phosphorites in parts of the Middle Cambrian Beetle Creek Formation of N.W. Queensland. Queen. Geol. Surv. Pub., vol. 364, pp. 21. Fletcher, C.J.N. (1981) - Mineralization in the Cerro Mannow Carbonatite Complex, En. Bolivia. Appl. Er. Sci., vol. 90, pp. 13-37. Flicoteaux, R. et al« (1977) - Genese des phosphates alumineaux a partir des sediments argilo-phosphate du Tertiaire de I amlam (Senegal). Sci. Geol± Bull., vol. 30, no. 3, pp. 153-174. Folk, R.L. (1959) - Practical classification of limestone. Bull. Aroer. Assoc. Petrol. Geol.,vol. 43, pp. 1-38. (1962) - ^ectral sub-division of limestone types. In s W.E. Ham (Ed.), classification of carbonate rocks; a symposiun Amer. Assoc. Petrol. Geol. Mem., vol. 1, pp. 62-84. (1988) - Petrology of sedimentary rocks. Austin. Univ. of Texas Hemphill Pub. Co., pp. 170. 445 FreaC* D.H. and Riggs, S.R. (1965) - Stratigraphy and sedimenta tion of phosphorite in the Central Florida phosphate district. Presented at Ann. Meet, AIME Chicago, pp. 17. Freeman, M#R. (1977) - Phosphate Rocks. Mining Am. Rev. June, 1977, year, pp. 104-107. Frohlick, F. (1960) - Beitrag zur geothemic des chroms. Geochim. et Cosm. Acta# 20, pp. 215-240. Fuller, A.O. (1979) - Phosphate occurrences on the western and southern coastal areas and continental shelves of S. Africa. Eco. Geol., vol. 74, no. 2, pp. 221-237. Fyfe, W.S. et al. (1978) - Fluids in the earth's crust. N. Holland Amsterdam, pp. 198« G - SERIES Garrais,R«M. and Christ, C.L. (1965) - Solutions minerals and equilibrium. Harper and Row, N«Y., pp. 450. Garrels, R»M. and Mackenzie, F.T. (1971) - Evolution of scdi* mentary rocks. Norten, H.O.N.Y,, pp. 397. et al. (1975) - Chemical cycles and the global environ ment. William Kaufman, Inc. Co., Cal», pp. 256. Gavshin, V.M. et al- (1973) - The two types of uranium accuBKila* tions in rocks by sorption. Geochem. Inter., pp. 682-690. Gerasimoviskiy, V.I,^. et al. (1973) - Phosphorus in the effusive rocks of the E. African Rift zone. Geochim Int. Vol. 10, no. 2, pp. 260..265. Ghosh, D.B. (1975) - Geology through pictures s Section view of large stratifera stromatolites - Bijavar limestone, ind. Minerals, 29(4), pp. 1-3. (1981) - The Vindhyan basin in Bundelkhand Son-valley region. Misc. Publ. G.S.I., no. 50, pp. 75-88. Ghosh, S.K. (1988) - Trace metals in ferromanganese nodules and host sediments of the Indian Ocean, Jour. G.S.I., vol. 32, no. 1, pp. 40-47. 446 Gibbs, R.J. (1970) - Mechanism controlling world water chemistry. Science, vol. 170, pp. 1088-1090. ^^^^^^_^__^^_^ (1980) - Sites of river derived sediments in Ocean. Geology, 9, pp. 77-80. Gibson, T.G. (1967) - Stratigraphy and palaeoenvironment of the phosphatic Miocene strata of N. Caroline. G.S. Amer. Bull. 78(5), pp. 631-640. Gilinskaya, L.G. et al. (1984) - Mineralogy of apatite of Ancient phosphorites. G.S.I. Sp. Pub. no. 17, pp. 23-30. Giresse, P. (1980) - Phosphorus concentrations in the unconso- lated sediments of the tropical Atlantic shelf of Africa S. of £quator-Oceanographic conments, pp. 101-106. * Glasby, G.P. (1972) - Ttie geochemistry of manganese nodules from N.W. Indian Ocean. In s D.R. Horn (Ed.) - Perromanganese deposits on the ocean floor. Arden House and Lament Doherty Geological observatory, N.Y., pp. 93-104. (1977) - Marine manganese deposits. Elsevier Oceano- graphic series, v61. 15, pp. 523. Gokhale, K.V. and Rao, D.M. (1950) - Rock phosphate deposits. Ore Deposits of India, pp. 124*«131. Goldberg, E.D. and Parker, R.H. (I960) - Phosphatized %food from the Pacific sea-floor. Bull. Geol. Soc» Amer., vol. 71, no. 5, pp. 631-632. Goldman, M«I« (1922) - Basal glauconite and phosphate beds. Sci., vol. 56, pp. 171-173. Goldich, S^S* (1973) - Ages of Precambrian banded iron-formations. Eco. Geol., vol. 6, pp. 1126-1134. Goldschmidt, V.M. (1937^ a) - The principles of distribution of chemical elements in minerals and rocks. Jour. Chemical Soc, vol. I, pp. 655. Goldschmidt, V.M. (1954) - Geochemistry of phosphate. Oxford Calerendav Press, pp. 730. Govett, G.J.S. (1966) - Origin of banded iron-formations. G.S. Amer. Bull., vol. 77, pp. 1191.1212. 447 Gowda, M.J.C. and Rajulu, B.v.G. (1980) - Stromatolites of the Kaladgi basin and their significance in palaeoenvironmental studies. G.S.I. Misc. Pub. no. 44, pp. 220-239. Grabau, A.W. (1919) - Prevailing stratigraphic relationship of the bedded phosphate deposits of Europe, N. Africa, ^* America. Geol. Soc. Ainer. Bull., vol. 30, pp« 104« Graham, W.A-P* (1926) - Experiments on the origin of phosphatic deposits. £co. Geol., vol. 20, pp. 319-321• Graham, H«W. et al« (1954) - Phosphorus content of waters along the west coast of Florida. U.S. Fish and Wild Life service spec. Science Rept. Fisheries, no. 122, pp. 1-43, Grahm, W.F. and Duce, R.A. (1979) - Atmospheric pathways of the phosphorus cycle. Geochim et Cosm. Acta, vol. 43, pp. 1195-1208. Graf, D.L. (1960) - Geochemistry of carbonate sedimentary rocks. I-IV. Illinois State Geol. Surv. Circ, pp. 297-298. Green, J. and Polervaart, A* (1958) - Petrochemical fields and trends. Geochem. et. Cosm. Acta, vol. 13, pp. 87-122. Green, J. (1959) - Geochemical table of the elements for 1959. Geol. Soc. Amer. Bull., vol. 70, pp. 1127-1184. Gross, G.A. (1980) - A classification of Iron-formations based on depositional environments. Canad. Minerals, vol. 18, pp. 215-222 Gulbrandsen, R.A* (1937) - Phosphoria Formations. £co. Geol., vol. 32, pp. 535. (1960^ a) - Minor elements in phosphate of the Phos phoria Formation. Bull. G.S. Amer. 71, pp. 1576. (1960^b) - petrology of the Mead Peak phosphatic shale member of the Phorponta Formation at Coal Canyon Wyoming. Bull. U.S.G.C., 1111-C.,C-71 - C-146. et al. (1966) - Carbonate bearing apatite from Faraday Township, Ontario, Canada. The Amer. Min., vol. 51, pp. 819-824. (1966, a) - Chemical composition of phosphorites of the Phosphoria Formations. Geochem et Cosm. Act, vol. 30, pp. 769-778. (1969) - Physical and chemical factors in the formation of marine apatite. Eco. Geol., vol. 64, no. 4, pp. 365-382. m (1970) - Relation of carbon-di-oxide content in the apatite of the Phosphoria Formation - the regional facies. U.S.G.S. Prof. Paper, 700 B, pp. B.9-B.13. ^^____^_^_^ and Ruberson, EmE» (1973) - Inorganic phosphoria in sea water* In s Environmental Phosphorus Hand book, E.j, Wiley, Inter Sci., S.Y. CH-5, pp. 117-140. (1977) - By product resources in phosphate ore of S.£. liaho. Geol. Soc. Aroer., vol. 9, pp. 728. et al. (1984) - Time and crystallization of apatite in sea water. Geochem. et. Cosm. Acta/ vol. 48, no. 1/ pp. 213-218 Gulick, A. (1955) - Phosphorus as a factor in the origin of life. Amer. Scientist, vol. 43, pp. 479-489. Gupta, P# et al. (1988) - Delhi volcanics in parts of Central Rajasthan and their significance. Jour. G.S.I., vol. 31, no. 3, pp. 314-327. H - SERIES Habshi, F. (1962) - Correlation between the uranium content of marine phosphates and other rock constituents. £co. Geol., vol. 57, pp. 1081-1084. Haider, D. and Ghosh, D.B, (1981) - A discussion on the un certainties in the dating of the Vindhyan and Bijawar rocks. Misc. Pub. G.S.I, no. 50, pp. 223-228. Hart, I.J. and Curry, R.I. (1960) - The Benguda current. Discovery Rept., vol. 31, pp. 123-298. Hashmi, N.H. (1971) - Note on the Geology of the wn. Liddar valley, Kashmir. Him. Geol., vol. 1« pp. 284-287. Heath, G.R. (1974) - Dissolved silica and deep sea sediments, in studies in palaeo-oceanography, Ed. W.W. Hay, SEPM Sp. Pub. no. 2, pp. 77-93. Heinrich, B.W. (1958) - Mineralogy and Geology of radioactive raw materials. McGraw Hill Book Co. Inc. N.Y./ pp. 595. 449 Henderson, P. (1968) • The distribution of phosphorus in the early and middle stages of fractionation of some basic layered intrusions. Geochemica et. Cosm, Acta# vol. 32, pp. 897-911, Hendricks, S#B. et al. (1932) - The crystal structure of some natural and synthetic apatite like substance. Zeitschr. Krist., vol. 81, pp. 353-369. Heron, A.M. (1917) - The Geology of N.E. Rajputana and adjoining district. Memoir G.S.I., vol. 45, pt. I, pp. 1-128. ^^^__^^^ (1936) - The Geology of the s«E. Mewar. Mem. G.S.I.# vol. 68 U)# pp. 1-15. Herzenberg, C.L. and Riley, D.L. (1969) - Interpretation of the Mossabaner spectra of marine iron-manganese nodules. Nature, vol. 224, pp. 259-260. Higgins, M# (1971) - Cataclastic Rocks. Prof. Paper, U.S.G.S., vol. 687, pp. 1-97. Hills, T. (1962) - Marine phosphate deposits. The Sea# 3, pp. 612-614. Holland, H#D. (1973) - The Oceans - a possible source of iron in iron-formations. Kco. Geol., vol. 68, pp. 1169-1172. ^^^ (1984) - The chemical evolution of the atmosphere and ocean. Princeton Univ. Press, pp. 582. Howard, P*P. (1972) - Es^loration for phosphorite in Australia - A case history. Eco. Geol., 67, pp. 1180-1292. (1979) - Phosphates. Eco. Geol., vol. 74, no. 2, pp. 192-1^4. and Hough, M.J. (1979) - On the geochemistry and origin of the D* Tree, Wonarah and Sherrin Creek phosphorite deposits of the Georgia basin, N. Australia. Eco. Geol., vol. 74, no. 2, pp. 260-284. Huber, N.K. (1959) - The environmental control of sedimentary iron minerals. Eco. Geol. 53(2), pp. 124-140. Husain, 2. (1977) - Petrographic and geochemical study of the phosphorite bearing rocks in and around Tighora village, distt. Sagar (M.P.) (Unpub.), Dissert, of M.Phil., pp. 179. 450 I - SERIES Ilyin, A.V. and Ratnikova# G.l. (1976) - Rare-Earth distribution in the Hobso GOI. phosphorites, Mangolia# Geochim. Int., vol. 13, no. 5, pp. 53. ^__^___^^ and Bliskovsky, V#2. (1984) - Crystal chemical investigation of ancient apatite. G^S.I. Sp. Pub. no. 17, pp. 31-34• Ingle, J.C. Jr. (1973) - Sunmary coimnents on Neogene bio- stratigraphy, physical stratigraphy and palaeo-oceanography in the marginal north-eastern Pacific Ocean. In s Initial Rep. of the Deep Sea Drilling Proj, Kulu, L.D. et al. (Eds.), vol. 18, pp. 949-960. Israili, S.H. (1976, a) - Geochemistry and genesis of Matoon phosphorite deposits, Udaipur distt., Rajasthan, 125th Anv., G.S.I., Jaipur, Rajasthan (India)# pp. 12-13. (1976^b) - contribution of algal bodies in the genesis of Jhamarkotra, phosphorite deposits, Rajasthan. First Conven. India.Assoc. Sedimen to legists, Aligarh (U.P.), pp. 12. ^____^_^^^^ (1976^c) - Origin of Mussoorie phosphorite - a critical review. 125th Anniv. G.S.I., Luc3cnow, pp. 70-75. (1978) - Origin and classification of Indian phosphorites - A Geochemical Approach. 3rd Regional Conf. on Geology & Mineral Res. of S«£. Asia# Bangkok, Thailand, pp. 269-274. (1978) - Textures and structures of Jhamarkotra phosphorite deposits. G.S.I. Workshop on Stromatolites, pp. 18-32. and Khan, M.W.Y. (1980) - Trace Elements studies of phosphorite bearing Gangolihat dolomites, Pithoragarh, U.P. Indian Chem. Geol., 31, pp. 133-143. Ivanoff, A. (1972) - Introduction a I* Oceanographic properties physiques et Chimiques des eaux de mer., vol. 1, Vuibert, Paris, edit., pp. 208. 45t J - SERIES Jacob, K.D. et al. (1933) - The composition and distribution of phosphate rock with special references to the U.S. U.S. Deptt. of Agri. Tech. Bull. 8, pp. 343-349. Jaffe, E.B. (1951) - Abstracts of the literature on synthesis of apatites and some related phosphorites. U.S.G.S. Circ. no. 135, pp. 78. James, H.L. (1954) - Sedimentary tacies of iron formation. Eco. Geol., vol. 49, pp. 235-293. (1966) - Chemistry of the iron-rich sedimentary rocks. U.S.G.S. Prof. Paper, 440 W, pp. 63 Janardhan, A«S. et al. (1986) - Banded iron formation and associated manganiferous horizons of the Sargur supra-crystal, Sn. Karnataka. Jour. G.S.I., vol. 28, pp. 129-188. Jarvis, I. (1980 a) - Genesis and diagenesis of Santonian to early Campanian iCretaceous) phosphatic chalks of the Anglo- Paris basin. Unpub. D. Phil. Thesis, Dept. Geol., Min. Univ. Oxford, pp. 578. __^_^ (1980-b) - The initiation of phosphatic chalk sedimentation - The Senonian (Cretaceous) of the Anglo-Paris Basin. SEPM Sp. Pub. no. 29, pp. 167-192. (I98O9C) - Palaeobiology of Upper Cretabeleranites from the phosphatic chalk of the Anglo-Paris basin. Palaeon tology, 23, pp. 898-914. _^__^__^__ (1980, d) - Geochemistry of phosphatic chalk and hard grounds fxom the Santonian to early Campanian (Cretaceous) of N. France. Jour. Geol. Soc, 137, pp. 705-721. Jaffe, E.B. (1951) - Abstracts of the literature on synthesis of apatites and some related phosphorites. U.S.G.S. Circ. no. 135, pp. 78. Jensen, M.L. (1958) - Sulfur isotopes and the origin of sand stone type uranium deposits. Bco. Geol., vol. 53, pp. 598-616. Jhingran, A.G. et al. (1955) - Progress report for field season 1953-54 (A study for a part of the Bundelkhand Granites and Gneisses), pp. 85. 452 (1958) - Fourth-fifth Indian Science Congress Report, Madras. The •Bundelkhand Gneiss', pp. 1-23. (1970) - Problems of Bundelkhand granite and gneisses* Inaugural address Proc. 2nd Symp. Upper Mantle Proj. Dec, 1970, GRB, N.G.R.I., Hyderabad, India, pp. 65. Johnson, D.B. and Swett, K. (19 74) - Origin and diagenesis of calcitic and hematitic nodules in the Jordon sandstone of N.E. Iowa. Jour, of Sed. Petr., vol, 44, no. 3, pp. 790-794. K - SERIES Kajitani, K. (1968) - A geochetnical study on the genesis of Ningyoite the special calcium uraneus phosphate minerals. Geochem. Int., vol. 32, no. 2, pp. 618-628. Kanungo, S.B. and Sant, B.R. (1973) - Dephosphorisation of phosphorus-rich manganese ores by selective leaching with dilute nitric acid. The Q. J.G.M. and Met. Soc. India, vol. 45, no. 3, pp. 87-95. Kapur, R.P. (1980) - Presidential address of workshop on stromatolites. G.S.I. Misc. Pub. no. 44, pp. xi-xli, Kazakov, A.V. (1937) - The phosphorite facies and the genesis of phosphorites. In s Geol. In : Geol. Inv. Agri. Ores ^rans. Sci. Inst. Pestl. Insecto. U.S.S.R. no. 142, pp. 95-115. (1950) - Pluorapatite system equilibria under conditions of formation of sedimentary rocks. Akad. Hauk. S.S.S.R., Inst. Geol. Naak. Trudy, vol. 114, Geol. Series, no. 40, pp. 1-21. Khan, S.U. (1968) - Bijawar Series - A note, pp. 1-10, Dept. of Geology, Saugar Univ^, Sagar (M.P.). and Das, B. (1968) - Stromatolitic structures from the type area of Bijawar rocks; Chhattarpur distt., M.P.(India) Curr. Sci., 37(6), pp. 171-172. Khan, M.W.Y. (1978) - Geology and geochemistry of phosphorites of Pithoragarh, U.P. (unpub.), Ph.D. thesis,A.M.U., Aligarh, pp. 178. 453 Khan, M.N« et al« (1981) - Geocheraical characteristics as applied to the genesis of Precanibrian phosphorites, Jhabua distt., M«P#, G.S.I. Sp. Pub. no. 3, 'Archean of Central India*, pp. 411-463. Kholodov, V.N. (1973) - Trace elements distribution in the Kurumsak-Chulakta. Geochem. Inter., vol. 10, pp. 795-802. Khudolozhkin, V.O. et al. (1972) - Ordering of calcium and strontium in cation positions in the hydroxylapatite-Belovite isamorphous series. Geochem. Int., vol. 9, no. 5, pp. 827. Kimmerer, W.J. and Walsh, T.W. (1981) - Tarawa Atoll lagoon t Circulation, nutrient fluxes and the Impact of human waste. Micronesica# 17, pp. 161-179. Kimrey, J.O. (1965) - Description of the Pungo river formation, Beaufort county, N. Carolina : N.C. Dept. Conservation and Devel. Dlv. Mineral. Res. Bull., 79, pp.131. Kinsey, D.W. and 0avies« P.J. (1979) - Effects of elevated nitrogen and phosphorus on coral reef growth. Llmnol. Oceanogr., 25, pp. 939-940. Klemme, H.D. (1958) - Regional geology of Circum Mediterranean region. Amer. Asspc. Petrol. Geologists, vol. 32, pp. 477-512. Klotz, I. (1968) - Chemical thermodynamics, Wiley Intersci. Pub. Co., pp. 218. Kolodny, Y. (1969. a) - Arc marine phosfihorltes forming today? Nature, vol. 224^ pp. 1017-1019. (1969, b) - Studies in geochemistry of uranium and phosphorites. Dissert. Univ. of Call«, Los Angeles^ Call.# U.S.A. (In press) - Genesis of phosphorites in view of recent and young sea-floor phosphorite occurrence. and Kaplan, X.R. (1970) - Uranium Isotopes in sea- floor phosphorites. Geochem. et. Cosm. Acta, vol. 34, pp. 3-24. (1979) - Origin of phosphorites in the light of recent studies of modern deposits. In t Rept. on marine phosphatic sediments, workshop* Honolulu (Eds.). Bumett# W.C. and Sheldon, R.P.« pp. 7-8. 454 (1980) - The origin of phosphorite deposits in light of occurrences of Recent Sea-floor phosphorites, SEPM. Sp« Pub* no. 29, pp. 249. (1981) - Phosphorites in Emiliani C. ed. The oceanic lithosphere - The Sea# vol. 7, nN.Y. John Wiley & Sons, pp. 981- 1023. Koritnig, S. (1970) • Phosphorus. In s Handbook of Geochemistry-I2 2(15-F) ed. K.H. Wadepohl, pp. 7-8. Kozlov, A.A. (1975) « On the distribution of uranium in the phosphorites of the Russian platform. Geochem. Int., vol. 12, no. 2, pp. 136. Krammer, i7«R. (1964) - Sea water saturation with apatite and carbonates. Sci., vol. 146, no. 3644, pp. 637-638. and Roberson, M. (1966) - Phosphorites - mineralogy. sea water chemistry and mineral formation - Abstract, 2nd Oceanogr. Congress, Moscow, pp« 205. Krauskopf, K.B. (1938) « Calciuot-Phosphates. Introduction to Geochenistry (1st Ed.), pp. 88*93. _^.^ (1955) - Sedimentary deposits of Rare-metals and ore-minerals. Eco. Geol., 50th Anniv., vol. 18, pp. 411-463. ^^_^^^^__^^^_^ (1956^ a) - Dissolution and precipitation of silica at low tenperature. Geochem. et. cosm. Acta, 10, pp. 1-27. (1956^b) - Factors controlling the concentrations ot 13th elements in sea water. Geochem. et. Cosm. Acta, vol. 9, no. 6, pp. 1-32. ^^__^^ (1959) - separation of manganese from iiron in sedimentary processes. Geochem. et. Cosm. Acta, 12, pp. 61-84. ___^ (1967) - Introduction to Geochemistry. McGraw Hill Book Co., N.Y. (2nd Ed.), pp. 721. Kreidler, E.F. and Hummel, F.A. (1970) - The crystal chemistry of apatite structure fields of fluor and chlorapatite. Amer. Hinerale, 55, pp. 170-184. Krishnan, M.S. (1942) - Phosphates. Rec. G.S.I#, vol. IiXXVI, Bull. Eco. Minerals, vol. 4, pp. 420, 455 (1956) - Geology of India and Burma, Hlgginbothams, 3rd Ed., pp. 203-204. and Swamlnath, J. (1959) - The great Vindhyan basin of N. India, Jour. G^S.I., vol. 1, pp. 16-30. (1961) - The structural and tectonic history of India Mem. G.S.I., vol. 81, pp. 1-137. (1968) - Bijawar Series. Geology of India and Burma (5th fid.), pp. 16-68. Krishnaswamy, S. (1945) - Mineral Investigations by Geol. Surv. of India during field season, 1945-46, pp. 1-10. Krumbein, W.C. and Garrels, R.M. (1952) - Origin and classifi cation of chemical sediments in terms of pH and oxidation- reduction potentials. Jour. Geology, vol. 60(1), pp. 1-33. Krynin, P.D. (1949) - The origin of red beds s N.Y. Academy of Sciences, Trans-section series II, vol. 2, pp. 60-68. ^^^ (1950) - Petrology, stratigraphy arid the origin of the Triassic sedimentary rocks of Connecticut. Conn. Geol. Nat. History Survey Bull., 73, pp. 239. L - SERIES Laajoki, K. and Saikkonen, R* (1977) - On the geology and geochemistry of the Precambrian iron formation, in Vargrylanka# S. Puolanka area, Finland. Finland Geology Surv. Boll., vol. 292, pp. 137. , (in press) - the Precambrian supracrystal rocks of Finland and their tectono-exogenic evolution. (1986) - Main features of the Precambrian Banded Iron Formation of Finland. Jour. G.S.I., vol. 28, no. 2 and 3, pp. 151-170. Lacroix, A. (1910) « suv La constitution mineralogique des phosphates francais t Comptes Rendus Soc. Geol. France, vol. 150, pp. 1213. 456 Langmuir^ D. (1978) - Uranium solution inineral equilibria at low temperature with application to sedimentary ore deposits, Geochem, et. Cosm* Acta, 42, pp» 547-569. LeGeros, R.Z. (1965) - Effects of carbonate on the lattice parameters of apatite. Nature, 206, no. 4982, pp. 403-404. et al. (1967) - Apatite crystallites. Effects of carbonate on aineralogy. Sci., vol. 155, no. 37$8, pp. 1409. Lehr, J.R. et al. (1968) - Characterization of apatites in commercial phosphate rocks. Internat. Colloquium. Solid Inorg. Phosphates.'Tonlouse Prance, 1967, Proceed, vol. 2, May 16-20, pp. 29-44. Lehr, J.R. (1969) - Characterization of phosphate rocks from India. Unpub. Rept. CoBBUOra. to D.M. Banerjee (July, 1969). Lehto, T. and Niiniskorpi, V. (1977) - Poljois-Ja-Itla-Snomen rantamuodostuaat summary* The iron formations of N and « Finland. Geol. Surv. Finland Rept. Invert., vol. 22, pp. 49. Lermop, A. et al. (1975) - Modelling of geochemical cycle. Phosphorus as an exanqple. MSm. Geol. See. Amer., 143, pp. 205-218. Liang, T«Y. and Chang, A.C. (1984) * On the characteristics and genesis of Late Precambrian phosphorites associated with Gondwana Plate. G.S.I. Sp. Pub. no. 17, pp. 47-62. Livingstone, O.A. (1963) - Chemical composition of rivers and lakes in Fleischer, Michael, Editor, Data of Geochemistry. 6th Ed. U.S.G.S. Prof. Pe^er, 440vG, pp. G1-G64. Lodha, T.R. et al. (1984) - Characterization of low grade rock phosphates aa^ their beneficiation for fertilizers industry. Chem. Age of India, vol. 35, no. 1, pp. 15-22. Longkang; s. and zhendong, Y. (1988) - :nie metamorjihic petrology of the Susong Group and the origin of the Susong phosphorite deposits, Anhui Province. Precamb. Res. 39, pp. 65-76. Lucas, J. and Prevot, L. (1975) - Les marges Continentales pieges geochimiques : 1* example de La marge atlantique de 1* Afriqoe a La limite Cretace-Tertiare. B.S.G.P. 7, no. 4, pp. 496-501. et al. (1978) - Les phosphorites de La marge nord de I' Espagne, Chimie mineralogic genese. Oceanologica Acta, vol. 1, no. 1, pp. 55-72. 457 et al« (1978jja) - ^es phosphorites de La marge nord de I* Espagne, Chimie^ mineraloglc genese. Oceanol. Acta# vol* Ir pp. 107-.118. _^___^___^_^ et al« (1979) - Etude mineralogique et geochimlque de la serie phosphate du sud - est de la Tarquie (Mazidagi Mardin). Sci. Geol. Bull., vol* 32, pp. 15-22, ^____^^__ et al. (1979, a) - Phosphorites et evaporites s deux formations de milieux sedimentaires voisins etudiees dans la coupe du paleogene de foum selja (Metla -oui« Tunisia), Bull. Sci« Geol. Strasbourg., vol. 32, pp. 6<-ll. -_— ^^ ^^* (1^79,b) - Le-gisement de phosphate de Chaux de Taiba (Senegal) unexarople d* enrichissemont par alteration. Sci. Geologiques Bull. 32 (1/2), pp, 39-58. _^______^^ et al. (I979^c) - Les phosphorites rubefiees de Sidi Daoui. Transformations meteorique locale du gisement de phosphate des onled Abdoun (Maroc) • Sci. Geol. Bull.^ vol. 32, pp. 65-69. et al. (1980) - Different aspects of phosphorite %feathering, 1.0th Inter. Congr. Sedim. Jerusalem, pp. 41-52. et al. (1980) ~ Mineralogical and geochemical studies of the phosphatic formations in S.E. Turkey. SEPM So. Pub. no. 29, pp. 149-152. et al. (1980) - Petrology, mineralogy and geochemis try of the Late Precambrian phosphate deposits of Uranium volta# W. Africa. Jour. Geol. Soc.^137, pp. 787-792. Lucas# J. (1984) - Synthese De L* ^atite parvoice bacterienne a partire De matiere organique phosphatee et de divers carbonate^ de calcium dans des eaux donee et marine naturelles. Chem. Geol. 42, pp. 101-118. Lvorich, M.I. (1973) - The world water, Mir Publ., Moscow, pp. 212. M - SERIES Mabie, C.P. and Hess, H.D. (1964) - Phosphate study ani classi- tication of western phosphate-ores. U.S.3.M. Rept. Inv. 6466, 458 & (1974) - Petrographic study and classification of western phosphate ores. U.S#B.M. Rept, Investig., 6468, pp, 1-68, Mahabaleshwar, B. (1985) - Precarabrian Banded iron formation of India* Jour« G.S.I., vol. 26, no. 11, pp. 825-832. Mahadevan, T.M. (1986) - Space controls in Precambrian uranium mineralisation in India. Jour. G.S.I., vol. 27, pp. 47-62• Maisonneure, J. (1980) « The composition of Precambrian Oceans waters. 26th Inter. Geol. Congr. Paris, France-II, pp. 507. Mallet, P.R. (1869) - (a) Vindhyan Rocks in Bundelkhand (b) On the Vindhyan series'^ as exhibited in the N.w. and Central provinces of India. Mem. G.S.I., vol. 7(1), pp. 1-60 and pp. 79.129. (1972) - Bundelkhand complex. Mem. G.S.I., vol. VI, pp. 1-30, Mancuso, J.J. et al« (1975) - Carbonate-apatite in Precambrian cherty iron formation, Boraga county Michigan. Eco. Geol., vol. 7 0, no. 3, pp. 583-586. Manheim, F.T. et al. (1975) - Marine phosphorite formation off Peru. Jour. Sed. Petr., vol. 45, no. 1, pp. 243-251. ^^_^_^___^^ and Gulbrandsen, R.A. (1979) - Marine phosphorites. Marine Minerals, vol. 6, pp. 151-173, Editor R.G. Burns. —...^ ®* al- (1980) - Composition and origin of phosphorite deposits of the Blake Plateau. SEPM Sp. Pub. no. 29, pp. 117-138. Mansfield, Q.^» (1940) - The role of fluorine in phosphate deposition. Aroer. Jour. Sci., vol. 238, no. 12, pp. 873-879. (1940) - Phosphate deposits of U.S.A. Eco. Geol., vol. 35, no. 3, pp. 405-429. Marsh, J.A. Jr. (1977) - Terrestrial inputs of nitrogen and phosphorus on fringing reefs of Gaum Proc. 3rd Inter. Coral Reef Symp., Miami, 1, Biology, pp. 331-336. Martens, C.S. and Harriss, R.C. (1970) - Inhibition of apatite precipitation in the marine environment by magnesium ions. Geochem. et. Cosm. Acta, vol. 34, pp. 621-625. Martin, D.F. (1980) - Marine Chemistry. Mareel Dekker Inc., N.Y* 2, pp. 210-211 459 Martin, M. and Meybeck, M. (1979) - Chemical composition of riverine particulates. Marine Chemistry, vol, 9, pp. 212-253. g (1980) - Composition of river input to world ocean. Marine Chemistry, vol. 9, pp. 1-15. Martin, J.H. and Knauer, G.A. (1973) - The elemental composi tion of plankton."Geochem. et. Cosm. Acta# vol. 37, pp. 1639- 1653. and Meybeck, M. (1979) - Elemental mass balance of material carried by major world rivers. Marine Chemistry, vol. 7, pp» 173-206. Mason, B. (1958) - Principles of Geochemistry. N.Y., Ilnd Ed., pp. 56-65. _^^^__^__^^ (1962) - sedimentation and sedimentary rocks. Principles of Geochemistry. N.Y. Ilird Ed., pp. 149-191. (1966) - Geochemistry and Meteorites, pp. 239. Mathar, P.C. (1954) - A note on the granitixation of quart- zites in Bundelkhand. Sci. & Culture, vol. 20, pp. 242. ^_^^^_^^_^^^_^ (1955) - Zircon in Bundelkhand granites and associated rocks. Current Sci., vo., 55, pp. 119-120. Mathur, S.M. and Singh, H.N. (1958) - A note on traverses through Bijawar rocks, Chhattarpur district (M.P*), June, 1958. (1960) - A note on the Bijawar Series in the eastern part of the area, Chhattarpur district (M.P«), India. Rec. G.S.I., vol. 86, pp. 539-544. and Mani, G. (1978) - Geology of the Bijawar Group in the type area, M.P. Proc. Symp. on Purana formations of Peninsular, India, Univ. Saugar, Sagar, M.P«, pp. 313-320. Mathur, R.K. (1981-82) - Mineral Investigation Reports of Jhabua distt. (M.P.). Rec. G.S.I., vol. 116, part 1, pp. 58. Maughan, E.K. (1966) - Environment of deposition of Permian salt in the Willisten and Alliance basins. Ilnd Symp. on Salt, vol. 1, N. Ohio Geol, Soc. Cleveland, Ohio, 1865, pp. 443. McArthur, J.M. (1974) - The geochemistry of phosphorite from the continental margin off Morocco, Unpub. Ph.D. Thesis, Imperial College, London^ Univ. London. m McArthur, J.M« (1978^ a) - Systematic variations in the contact of Na* CO3 and SO4 in marine carbonate-fluorapatite and their relatio to weathering. Chem. Geol., vol. 21, pp. 1639-1653. ^___^_^^__^ (1978, b) - Element portioning in ferruginous and pyritii phosphorite from the continental margin off Morocco. Mineral Mag.# vol. 42, pp. 221-228. ^ (1980) - Post-depositional alteration of the carbonate- fluorapatite phase of Moroccan phosphates. SEPM. Sp. Pub. no. 29, pp. 53-60. (1985) - Prancolite-geochemlstry •• con^ositional controls during formation, diagenesis, metamorphism and weathering Geochim. et. Cosm. Acta, vol. 49, pp. 23-35. ^_^^^ et al. (1987) - Phosphorite Geochemistry. Isotope evidence for meteoric alteration of francolite on a local scale. Chem. Geol., 65, pp. 415-425. McClellan, G. and Lehr, J. (1969) - Crystal chemical investigation of natural apatites. Ametr. Min., 54 (9-10), pp. 1374-1391. (1980) - Mineralogy of carbonate-fluorapatite. Jour. Geol. Soc. London, 137, pp. 675-682. McConnell, D. (1938) - A structural investigation of isomorphism of the apatite group. Amer. Min«, vol. 23, pp. 1-19. (1950) - Petrography of phosphate deposits. Jour. Geol* vol. 58, pp. 16-23. ^ (1952) - The crystal chemistry of carbonate apatite and their relationship to the composition of calcified tissues. Jour. Dental Res., vol, 31, pp. 53-63. (1952) - The nature of rock phosphate teeth and bone. T.W. Acad. Series, vol. 42, pp. 36. ^_^^^___^^___^ (1953) - Radioactivity of phosphatic sediments. Eco. Geol., vol. 48, pp. 147-148. (1963) - Inorganic constituents in the shell of the living frachiopod-iiingula. Geol. Soc. Amer. Bull., vol. 74, pp. 363-364. m ^^_^_^^__^^__ (1963) - Apatites : Its Geochemistry, Geology and biologic occurrences, Springer-Verlag, pp. 312, ______^ (1965) * Precipitation of phosphate in sea water. Eco. Geol., vol. 60, pp. 1059-1062. (1965) - Deficiency of phosphate iron in apatite. Nature, vol. 52, pp. 183. (1966) - Shallow water phosphorites. Eco. Geol., vol. 61, pp. 967-968. (1970) - Arsenic in phosphorites and apatites. Eco. Geol., vol. 65, no. Ir6, pp. 64-65. _^____^_^__ (1971) - Crystal chemistry of phosphate. Eco. Geol;, vol. 66, pp. 1085-1086. _^^_^^ (1973) - Apatites : Its crystal chemistry, mineralogy, utilization, geologic and biologic occurrences. N.Y. Springer- Verlag, pp. 111. McKelvey, V.E. and Nelson, J.M. (1950) - Characteristic of marine uranium bearing sedimentary rocks. Eco. Geol., vol. 45, pp. 35-53 et al. (1953) - The Permian phosphorite deposits of Wh. United States. In s 19th Int. Geol. Congr. Comp. Rand Sec. XI, Fasc. (II), pp. 45-65. et al. (1955) - Origin of uranium deposits. Eco. Geol. (50th Anniv. volume), pp. 464-533. _— ^^'^ Carswell, L.D. (1956) - Uranium in the Phosphoria Formation. Int. Conf. peaceful uses atomic energy, Proc. Geneva, vol. 6, pp. 551-561. (1956) - Uranium in phosphate rocks. U«S.G.S» Prof. Paper, 300, pp. 477. et al. (1959) - The Phosphoria Park city and Sheldhorn Formations in the Wn. phosphate field. U.S.G.S. Prof. Paper A-313, pp. 1-47. _^__^^__^^ (1959) - Relation of upwelling marine waters to phosphorites and oil. Geol. Soc. Amer. Bull., vol. 70, pp. 1783-1784. m (1967) - Phosphate deposits. U.S.G.S. Bull., 1252-D pp. D1-D22. (1973) - Abundance and distribution of phosphorus ii the lithosphere in Griffith,EJ; Beeton, A; Spencer, J.M. and Mitchell, D.T. (Eds.). Environ. Phosphorus Handbook, N.Y. Johi Wiley & Sons, pp. 13-30. McMahon, C.A. (1886) - Ndtes on the section from Simla to Wangtu and on the petrological characters of the amphibolites and quartz-diorites. Rec. G.S.I*, vol. 19, pp. 65-86. Medlicott, H.B. (1859) - Vindhyan rocks and their association in Buodelkhand. Mem. G.S.I., vol. II, pt. I, pp. 1-95. (1860) - Bijawar Series. Mem., vol; II, pp. 35. (1860) - On the geological structures of the Central portion of the Berbudda distt., Mem. G.S.I., II, pp. 138-216. (1868) -» The boundary of the Vindhyan Series in Rajputana. Rec. G.S.I. 1(3), pp. 69-72. (1876) - Note upon the sab-Himalayan series in the Jammu Hills. Rec. G.S.I. 9(2), pp. 49-57. and Blanford, W.T. (1879-87) - Bundelkhand Gneiss and schists. A manual of the Geology of India, vol. 2, pp. 1-55 and pp. 445-817. Mehta, D.R.S. (1944) - Mineral Investigations. Report,G.S.I., Field Season, 1944-45, pp. 1-8. Meybeck, M. (1979) - Dissolved load of world rivers. Rev. Geol. Dyn. Geogr. Phys., vol. 21, pp. 215-246. Miller, A.M. (1896) - The association of the gastropod genus cydora with phosphate of lime deposits. Amer. Geol., vol. 17, pp. 74-76. Miller, L.J. (1964) - The origin of sedimentary phosphate. Eco. Geol., vol. 59, pp. 1619-1623. Milliman, J.D. and Meade, R.H. (1983) - Vtorld wide delivery of river sediments to the Ocean. J. Geology, vol. 91, pp. 1-21. 463 Milner, H.B, (1950) - Phosphate deposits. Sedimentary Petrography, pp. 273-274. Minguzzi, C. (1941) - Per. Min. Roma I, 40. Mln. Abst. IX, pp. 283. Misra, R.C. (1948) - Hybrid gneisses in Bundelkhand. proc. 36th Ind. Sci. Congr., pp. 1-10. and Mathur, P.O. (1952) - Pre-Bundelkhand Granite rocks in Mahoba and Kabrai area, Harairpur. Proc. 22nd, Nature Acad. Sci., India, vol» 22, pp. 1-5. ^______^ and Saxena, M.N. (1955) - Variation in Bundelkhand gneisses. Proc. 42nd Ind. Sci. Congr., pp. 1-4. and Saxena, M#N. (1956) - Xenoliths and other older rocks of Bundelkhand granites type area, Bundelkhand Proc. 43rd Indian Sci. Congr., pp. 1-6. Misra, P.S- (1964) - Report on the preliminary Investigation of rock phosphate in Sirmur dlstt., H.P., G.S.I. Report. Field season, 1964-65, pp. 136. Misra, R.C. (1969) - The Vindhyan System. Presidential address, 56th Ind. Sci. Congr., Bombay, pp. 1-32. and Sharma, R.P. (1974) - Petrochemistry of Bundel khand granites and associated rocks of Central India. Ind. Mln., vol. 15, pp. 43-50. ' and Sharma, R.P. (1975) - New data on the geology of the Bundelkhand complex of Central India. In s Verma, V.K. et al. (ed.). Recent Res. in Geology, 2, pp. 311-346 (Hind Publ. Corp., Delhi). Misra, D.C. (1987) - Bljawar and Vindhyan tectonics of Central India from airborne megnetics and ground geophysical surveys. Purana Basins of Penln. India* Mem. No. 6, G.S.I., pp. 357*367. Mohammad, K.A. et al. (1981) - Comparison of three instrumental spectroscope techniques for elemental analysis of Kansas shales Allied Spect., vol. 35, no. 5, pp. 497. Mollazal, Y. (1961) - See development in sedimentology 9 A (Carbonate Rocks). Elsevier Pub. Co., London, N.Y., pp. 87-125. m Monty, C,L#V. (1976) - The origin of and development of cryptalgal fabrics. In s Stromatolites, Bevelop* la Sedim. Series No. 20, pp. 193-249. (Ed. M.R. Walters). Moorby, S.A. and Cronan, D.s. (1981) - The distribution of element between co«*existing phases # in some sarlne ferro- manganese-oxide deposits. Geochem. et. Cosm. Acta, vol. 45, pp. 1855-1877. Morris, R.C. (1986) - The cycling redox state of iron in the genesis of B*I«F. and their associated enrichnent iron-ores. Jour. G.S*I.# vol. 28/ pp. 227-236. Morse, J. (1979) - Fluxes of phosphate from ocean floor sediments. In s Marine Phosphate Sedlxaents, Vorlcshop., Hawaii# PP* 65. Mostert, S.A. (1966) - Distribution of inorganic phosphate and dissolved oxygen in the s-W Indian Ocean. Invert. Rept. Div. sea Pish, S. Africa, vol. 54, pp. 1-24. Mukherjee, B. and Chatterjee, P.K. (1972) - Xlneralogy of phosphorite from Udaipur, Rajasthan. Ind. Min., vol. 44, no. 2, pp. 101-103. Mullen, E. (1983) - MnO/Ti02/P205 - a major elei»eat discri minant for basalt rocks of ocean environnents and its impli cations for petrogeneses. Earth Planet Sci. Lett., vol. 65, pp. 41-58. Mullins, H.T« and Rasch, R,F. (1985) - Sea floor phosphorites along the Central California continental margin* See. Geol., vol. 80, no. 3, pp. 696-715. Murray* J* et al* (1891) - Report on deep sea deposits. Rep. Sci. Res. Voyaze of HMS. Challenger daring the year 1872- 1876, HMSU, London, CH-6, part 3, pp. 40C-S2S aocl pp. 378- 391. and Philippi, E. (1908) - Die Grand problem der deutschen Tiefsee expedition 1898-1899, vol-w 10, pp. 181- 187. Murrary, F.H. et al. (1983) - Immobilization of Vranium- Thoriuro-Radium in mine waters by phosphate mineralization. The Canad. Minerol., vol. 21, pt. 4, no. 83, pp* 607-610. m Murty, P.3.N. et al. (1973) - Partition pattern of iron, Mn, Ni and Co in the sediments off the W. Coast of India. Indian Jour. Mar. Sci•, vol. 2, pp. 6-12, et al. (1980) - Distribution pattern of Al, Mn, Ni ana Co and Cu in the non-lithogenous fraction of sediments of the northern half of the Wn. Continental shelf of India. Indian Jour, Mar. Sci., vol. 9, pp. 56-61. N - SERIES Naqvi, S.M. and Hussain, S,M. (1972) - Petrochemistry of early Precambrian metasediments from the Central part of the Chital- durga schist belt, Mysore, India. Chem. Geol., vol. 10,pp,lO9-135 Narain, H. (1987) - Geophysical constraints on the evolution of Purana Basins of India with special reference to Cuddapah, Godavari and Vindhyan Basins. Pur. Bas. of Penin. India. Mem. G.S.I., DO. 6, pp. 5->32. Nath, J.S. (1984) - Presidential address, IVth Inter. Field Vtorkshop and Seminar on phosphorite, India* G.S.I. Sp. Pub. no. 17, pp. (iv)-(vii). and Mukhferjee, S.K. (1987) - Annual general report of the G.S.I, for the year 1981-82. Rec. G.S.I., vol.116, part 1, pp. 319. Nathan, Y. and Lucas, J. (1972) - Synthesis of apatite from gypsum - application to the problem of the formation of carbonate-apatite by direct precipitation. Chem. Geol., vol. 9, pp. 99-112. and Lucas, J. (1976) - Experimentation on the direct precipitation of apatite in sea-water, implication in the genesis of phosphorites. Chem. Geol., vol. 18, pp. 181-186. and Shiloni, Y. (1976) - Exploration for uranium in phosphorites*- A new study on uranium in Israil* phospho rites. IAEA and NEA# pp. 645-655. et al. (1979) - The chemistry and geochemistry of the northern and central Negov phosphorites. Bull. Geol Surv. Isr. (in press). m (1980) - Structural positions of trace elements in apatites, implications for their recovery, Proc, 2nd Inter. Congr, on phosphorus compounds Institute Mondial du phosphate (IMPHOS), Boston, pp. 1-6. ^^^_^ and Sass, E. (1981) . Stability relations of apatite and calcium carbonate. Chem. Geol., vol. 34, pp. 103-111, Nauyen, T.C# (1984) - Etude theorique des conditions de formation et de stabilite des mineraux d* Uranium U02(c); USi04(C), CaU(P04)2.2H20; Ca(U02)2 ^^4 2;K2(U02)2 (VO4) dans Le domaine se dimentaire 5® Congr.-Europ. Sedim. Mar. Scille, Resumes., pp. 323-324. Notes and News (1959) - WOrldte largest deposit of rock- phosphate. Ind. Min., vol. XIII, no. 2, pp. 136. Notholt, A-J.G. (1979) - The economic geology and develop ment of igneous phosphate deposits, in Europe and the U.S.3#R. Eco. Geol., vol. 74, no. 2, pp. 339-350. and Hartley, K. (1983) - A bibliography of world resources. Mining Jr. Books, vol. 300, no. 7714, pp. 423. 0 - SERIES Odin, G.S. and Lettolle, R. (1980) - Glauconization and phosphatization environments - A tenative comparison. SEPM Sp. Pub. no. 29, pp. 227-238. Oldham, T. (1856) - Classified the Vindhyan sediments. Jour. Asiatic Society, Bengali vol. XXX, pp. 49. Oldham, R.D. (1887) - Preliminary sketch of the Geology of Simla and Jutogh. Rec. G.S.I*, vol.20, pp. 155-161. (1890) - Geology of India, 2nd Ed. CH-ii, pp. 320. Olsen, E. and Predriksson, K. (1966) - Phosphate in iron and pallasite meteorites. Geochem. et. Cosm. Acta, vol. 30, pp. 459-463. 467 P • SERIES Palmar, C. (1922) - Phosphorus in California petroleum. Eco, Geol., vol. 17, pp. 100-105. _^^__^_^ (1922) - Phosphorus metasomatism. Eco. Geol., vol. 17, pp. 116-121. Pant, A. (1978) - A report on the partition in Indo-Australian workshop on phosphorites under IGCP Project-156 "Phosphorites- Proterozoic, Cambrian? held in Australia between 13.8.1978 to 24.8.1978. unpub. Rept., G.S.I. U#P. Circle, N.R. Region, LucXnow, India, pp. 10. (1980) - Resource status of rocks phosphate deposits in India and areas of future potential. Proc. Fertilizer Raw Material Res. workshop, E-w Centre, Hnolulu, Sheldon, R.P. and Burnett, W.C. (Eds.), pp. 331-357. Park, C.F. Jr. and Roy, A. (1963) - Sedimentary deposits, "Ore Deposits*, pp. 387-389. Parker, R.J. (1971) - The petrography and major element geochemistry of phosphorite nodule deposits on the Agulhas Bank, S. Africa. 5. African Nat. Comm. for Oceanogr. Res., Mar. Geol. Progr. Bull. 2, Univ. of Cape Town, pp, 92-94. and Siesser, W.G. (1972) - Petrology and origin of some phosphorites from the s* African continental margin. Jour. sed. Petr., vol. 42, no. 2, pp. 434-440. (1975) - The petrology and origin of some glauco- nite -and glauco-conglomeratic phosphorites from the s. Africa, continental margin. Jour. Sed. Petr., vol. 45, no. 1, pp. 230-240, Paropkari, A*L. et al. (1981) - Distribution of phosphate in sediments of Gulf of Kutch. Jour. G.S.I., vol. 22, pp. 243- 246. Pascoe, E.H. (1950) - Metamorphism of granites - A manual of Geology of India and Burma. 1st Ed., vol. 1# part 1, pp. 484. (1959, 1962) - A manual of the Geology of India and Burma, vol. I, II and III, 2nd Ed., pp. 946-947. 468 (1965) - A manual of Geology of India and Burma 3rd Edn,, vol. I-V, pp. 529. Pasho, D.w. (1972) - Character and origin of marine phosphorites Geol. Dept., Univ. of S. California.Geol, Publ., vol. 12, no. 5, pp. 1-88. Patwardhan, A.M. and Ahluwalia, A.D. (1971) - Discovery of pre-Tertiary fossils indigenous to the Lr. Himalaya. Nature, 224r pp. 451-452. and Ahluwalia# A.D. (197J) - A note on the origin of Mussoorie phosphorite in the Lr. Himalaya/ India and its palaeogeographic implications. Min. Deposita, 8# no. 4, pp. 379-387. and Ahluwalia# A.D. (1975) - More evidence in favour of the biochemical origin of the Mussoorie phosphorite, Kumaon Lr. Himalaya* India. Min. Dep., vol. 10, no. 3, pp. 261-265. and Panchal, P«K« (1984) - Some textural features of Mussoorie phosphorites. G.S.I. Sp. Pub. no. 17, pp. 147-158. Pearce, J.A. (1975) - Basalt geochemistry using to investigate past tectonic environments on Cyprus. Tectonophysics, vol. 25, pp. 41-67. et al. (1977) - The relationship between major element chemistry and tectonic environment of basic and intermediate volcanic rocks. Earth Pla. Sci. Lit., vol. 36, pp.121-132. Petti John, F.J. (1957) - Sedimentary Rocks, 1st Ed., Harper and Bros. M.Y., pp. 718. (1969) - Non-clastic sediments. Sedimentary Rocks. 2nd Ed., pp. 428-434. ___^ (1975) - Phosphorite and other phosphatic sediments. Sedimentary Rocks. 3rd Ed., pp. 449-476. ^__^ (1984) - Phosphorites and other phosphatic sediments. Sedimentary Rocks. 4th Ed., pp. 427-432. Pevear, D.R. (1966) - The esturine formation of United States Atlantic coastal plain phosphorites. Eco. Geol., vol. 61, no. 1, pp. 251-256. m Pierrotu U. (1976) - The global phosphorus cycle, in s B.H. Svensson and R, Soderlund, SCOPE, Rep. 1, Ecolog. Bull. Stock., vol. 22, pp. 75-88. Piper, D.Z. and Codispoti, A. (1975) - Marine phosphorite deposits and the nitrogen cycle. Sci., vol. 188, no. 4183, pp. 15-18. Power, P.D. (1926) - Phosphate deposits of Pacific. Eco. Geol., vol. 20, pp. 266.291. Pradhan, V.S. and Deshpande, S.P. (1969) - Reduction of phosphorus in the manganese ores of India with particular reference to M*P. and Maharashtra. Indian Mining and Engg. Jour., vol• 8, 5-133. Pra)cash, R. et al. (1975) - Geology and mineralization in the Sn. part of Bundelkhand in Lalitpur distt., U.P. Jour. Geol. Soc. India* 16, pp. 143-156. Prasad, B« (1984) - Geology, sedimentation and palaeogeography of the Vindhyan supergroup, S.E. Rajasthan. Mem. G.S«I## vol. 116, part 1, pp. 1-107. Prevot, L. and Lucas, J. (1980) - Behaviour of some trace elements in phosphatic sedimentary formations. SEPM. Sp. Pub. NO. 29, pp. 31-40. Pric, S. and Rose, A.W. (1981) - Uranium anomalies in palaeo- aquifers near sandstone type uranium deposits in the Devonian Catskill Formation of Pennsylvania- Jour. Geochem* Expl., vol. 15, no. 1-3, pp. 219. Price, N,B. and Calvert, S.E. (1978) - The geochemistry of phosphorites from the Namibian shelf. Chem. Geol., vol. 23, no. 2, pp. 151-170, Proshlyakova, N.G. et al. (1987) - Geochemistry of V, Cr, Ni, Zn, Pb and As in the phosphorite bearing beds of the Dzhanates deposit, Malyy, Karatan basin. Geochem. Int., vol. 24, pp. 44-49. Q - SERIES ftasim, S.2. (1986) - Marine mineral potentials of the Indian ocean and India - Problem and products. India's Environment. G.S.I. Mem. No. 5, pp. 107-115. 470 R - SERIES Radhakirshna, B,F. (1987) - Red beds and phosphorites- Furana Basins of Penin. India. G.S.I* Mem. no. 6, pp. i-xii. (1987) - Geology of parts of the Bundelkhand Granite massif. Central India by A«K. Basu, Rec. G.S.I., vol. 117, pp. 61-124. Jour. G.S.I./ vol. 30, no. 3, pp. 245. Raha, P*K. (1987) - Stromatolites and correlation of the Parana basins of Penin. India. Mem. G.S.I. No. 6, pp. 393-397. Raikar, P.S. (1987) - Univariate and multivariate stochastic modelling and forecasting of silica content in iron-ores of N. Goa. Jour. G.S.I., vol. ?9, no. 3, pp. 349-355. Rajarajan, K. (1978) - Geology of Sagar district and western part of Damoh district, M.P« G.S.I. Mem.,vol. 109, pp. 1-99. Ramzy*s E. (1964) - Geology and petrography of the phosphates of the Quesir-Safaga region. Unpub. MC. Thesis, Faculty of Science, Assiat. Univ. Assuit., U.A.R., FP# 291. Ramsay, J.G. and Graham, R.H. (1970) - Strain variation in shear belts. Can. Jour. Ear. Sci., vol. 7, pp. 786-813. (1982) - Rock ductility and its influence on the development of tectonic structures in mountain belts. In s K.J. Hsu (Ed.). Mountain Bid. Proc. Acad. Press, London, pp. 111-127. Rao, A.S. et al. (1987) • Phosphorite in the Cuddapah basin, . A#P. Purana Basins of Penin. India, G.S.I. Mem. no. 6, pp. 511-518. Rao, B.K.N, et al. (1987) - Phosphorites in stratigraphy, structure and evolution of the Cuddapah basin. Purana Basins of Penin. India, G.S.I* Mem. no. 6, pp. 81. Rao, CH. M. et al. (1987) - Distribution of phosphorus and phosphatization along the western continental margin of India. G.S.I., vol. 30, no. 5, pp. 423-438. Rao, D.M. et al. (1974) - Mineraloglcal studies on Mussoorie phosphorites. Him. Geo!., vol. 4, pp. 240-246. Rao, G.V. et al. (1984) - Phosphorite. G.S.I. Sp. Pub. no. 17, pp. 210. 47t Rao, K.S. (1972) - Report on the measurements of stratigraphic thickness of Vindhyans in parts of Rewa, Satna, Sidhi and Panna distts-, M.P. Unpub. Report G.S.I-, pp. 29. Rao, N.K. and Rao, G.V.U. (1971) - Petrographic study of seme Indian phosphorites. Jour. G.S.I., vol. 12, no. 4, pp. 356-367. ___^ et al. (1979) - Lead isotopic ratios of uraninites and the age of uranium mineralization in Singhbhum shear zone, Bihar. Jour. G.S.I., vol. 20, pp, 124-127, Rao, V.D. et al. (1970) - Integrated geological, geophysical and geochemical studies near Tighora village, Sagar distt., M.P. Rept. N.G.R.I., Hyderabad-16, pp. 1-12. Rasmy, M. and Easily, A.B. (1983) - Spectrographic study of trace elements in some Egytian black shales associated with phosphate deposits. Chem. Geol:, vol. 39, no. 1/2, pp. 115-123. Reedman, J.H. (1984) - Resources of phosphate-niobium, iron and other elements in residual soil cover the Sukulu carbonate complex, S.E. Leganda. Eco. Geol., vol. 79, no. 4, pp. 716-724. Redfield, A«C. (1958) - The biological control of chemical factors in the environment. Amer. Scientist, vol. 46, pp. 205-221. Reineck, H.E. and Singh, I.E. (1980) - Depositional sedimentary environments (2n4 ed.), Springer-Verlag, Berlin, pp. 549. Riggs, S.R. (1978) - A petrographic classification of sedi mentary phosphorites. In : Proterozoic - Cambrian phosphorites, Ed.; Cook, P.J. and shergold, J.H. 1st Inter. Field Workshop and Seminar, I.G.C.P., 156, Australia, pp. 63-65. (1979^ a) - Petrology of the Tertiary phosphorite system of Florida. Eco. Geol., vol. 74, no. 2, pp. 195-220. __^ (1979yb) - Phosphorite sedimentation in Florida : A model phosphogenic system. Eco. Geol., vol. 74, no. 2, pp. 285-314. (1980) - Tectonic models of phosphate genesis. In s i'ert. Mineral, potential in Asia and Pacific. E-W center, Hawaii# pp. 481. 472 Roberson, C»E, (1966) - Solubility implications of apatite in sea-water. U.S^G.S, Prof. Paper, 550-D, pp. D-178 - D-185. Roday* P.P. et al. (1989) - Structural analysis of shear zone in basement granite and their relationship with folding, shearing and faulting in the cover sediments near Hirapur, distt. Sagar, Central India. Jour. G.S.I., vol. 33, no. 5, pp. 387-408. Rogers, A.F# (1922) - Cellophane, a much neglected mineral. Amer. Jour. Sci., Ser. 5, vol. 3, pp. 269-276. (1944) - Pellet phosphorite from Carmel valley, Monterey county, California. Calif. Jour. Mines Geol., vol. 40, pp. 411-421. Rogers, R.J. (1973) - Texture, composition and depositional history of unconsolidated sediments on the Agulhas Bank and the Orange-Luderitz continental margin. S. Afri. Nat. Comm. for Oceanogr. Res. -Mar. Geology Progr. Tech. Rept. 4, Univ. of Cape Town, pp. 44-59. (1977) - Sedimentation on the continental margin off the Orange River and the Namibia desert. Unpub. Ph.D. Thesis,Geology Dept., Univ. Cape Town, pp* 220, (1977) - Sedimentation on the continental margin off the Orange River and the Namibia desert. Joint Geol. Surv.A^niv. of Cape Town, Marine Geo. Sci. Bull., vol. 7, pp. 212v Romankevich, Y.A. and Baturin, G.N. (1972) - Composition of the organic matter in phosphorites from the continental shelf of S.W. Africa. Geo. Int., vol. 9, no. 3, pp. 464. Ronov, A«B« and Karozina, G.A. (1960) - Phosphorus in sedi mentary rocks. In s Dev. in Sedimentology, 98, pp. 90-125. Rooney, T.P. and Kerr, P#P# (1967) - Mineralogic nature and origin of phosphorite, Beaufort County, N. Carolina. G.S. Amer. Bull., vol. 78, no. 6, pp. 731-749. Roonwal, G.S. and Kumar, A. (1987) - Geochemical indicators for concealed Cu-2n-Pb mineralization in Rajpura, Udaipur, Rajasthan. Jour. G.S.I., vol. 29, no. 9, pp. 358-361. (1989) - Marine minerals in the Indian Ocean. Jour. G.S.I., vol. 34, no. 2, pp. 182-191. 473 Rougerie, F. and Waitthy, B. (1986) - Atoll-Oasis functioning and eudo-upwelling concept. Oceanol, Acta* vol. 9, pp. 133-146. Rouse, R.C. (1984) - Hedyphane. from Franklin, ^Jew Jersey and Langban, Sweden: Cation Ordering in an arsenate apatite. Amer. Min., vol. 69, no. 9 and 10, pp. 920-927. Roy, D.M. et al.# (1978) - Crystal chemistry, crystal growth and phase equilibria of apatites. In s A.M. Alper, Ed. Phase diagrams, vol. 5, pp. 185-239. Acad. Press, New York. Roychowdhuri, M.K. (1947) - Mineral Investigations by G.S.I, during Field Season, 1947-48, pp. 1-15. (1950) - Report on further Minerals Investigations in M.P., pp. 1-11. et al. (1955) - Economic geology and mineral resources of M.P. Bull, G,«S.I« Series A, no. 10, pp. 1-88. Roy, S. (1981) - Manganese deposits. Acad. Press, New York, pp. 458. Rubey, W.W. (1951) - Geologic history of sea water - An attempt to state the problem. Geol. Soc. Amer* Ball., vol; 62, pp. 1111' 1148. Russell, R.T. and Trueman, N*A. (1971) - The Geology of the Duchess phosphate deposits, N.W. Queensland, Australia. Eco. Geol., vol. 66, no. 8, pp. 1186-1214. S - SERIES Saffir, A.J. and Rubin, B. (1970) - The growth of calcium phosphate crystals by controlled diffusion in bio-simulated silica gels. Proc. 3rd Ann. Scann. Micro. Symp. Illinois Inst, of Tech.. Res. Instt., Chicago, Illinois, I, 11, pp. 201-208. Sahgal, P.K. and Raraesh, V. (1984) - Orthophosphates in the shallow ground waters of S. India. Jour. G.S.I., vol. 25, no. 12, pp. 787-791. Saigal, N. and Banerjee, D.M. (1986) - A study of Proterozoic phosphorites from Chelima-Pahcheria area in the Cumbum super group of Kurnool distt., A.P., India. Jour. G.S.I, (in press) 474 • and Banerjee, D.M. (1987) - Proterozoic phosphorites of IndiaJ Updated information Part I. Petrography. G.S.I, Mem. 6, Purana Basins of Penin. India, pp. 471-485. and Banerjee, D.M. (1987) - Part-II. Geochemistry, G.S.I. Mem. 6, Parana Basins of Penin. India, pp. 487-509. and Banerjee, D.M. (1987) - Proterozoic phosphorites from Chelima-Pacheria area, Kurnool distt., A.P.# India (in press)• Sahu, B.K. and Raikar, P.S. (1983) - Geochemical model for genesis of iron-ores in N. Goa. Proc. Workshop on geomodelling, I.I.T., Bombay, India, pp. 84-91. Sakanoue, M. et ai. (1968) - Alpha-radioactive nuclides of uranium, proteactinium and thorium in uranium deposits. Geochemistry Jour., vol. 2, pp. 71-86. Sankaran, A.V. et al. (1980) - Thermoluminescence studies in Geology, Rept. A.E.G. BARC, Bombay, India, pp. 1-35. Sant, V.N. and Sharma, S.B. (1984) - Geology of Kanpur phos phorite deposits, Udaipur distt., Rajasthan. G.S.I., sp. Pub. no. 17, pp. 105-110. Santosh, M. (1988) - Granite-Molybdenite system of Ambalavyal, Kerala : Part I, Geochem. and Petrogenesis of the granites, jour. G.S.I., vol. 32, no. 2, pp. 83-105. Saraswat, A.C. et al. (1970) - Geochemical data on the urani- ferous phosphorites of Mussoorie, Dehradun distt., U.P.(India). UNESCO-ECAFE. seminar on Geochem. prospecting and tech. Ceylon, sept. 10-20, 1970, pp. 1-11. Sarkar, S.N. et al. (1964) - Geochemistry of the Precambrian of Peninsular India - A synopsis. Sci. and Cult., 30, pp. 527- 537. et al. (1964) - Precambrian geochronology of Penin sular India. Proc. 22nd I.G.C. Part X, pp. 177. (1980) - Precambrian stratigraphy and geochemistry of Peninsular India. A Review. Ind. Jour. Ear. Sci. 7(i), pp. 1-3. Saxena, M.N. (1953) - Agmatites in Bundelkhand Granites and gneisses and the phenomenon of gravitization. Curr. Sci., vol. 22, pp. 376. 475 (1956) - Trench of variation in the heavy mineral percentages during the coarse of the gravitization of the country rocks of the type area. Sci. and Cult.# vol. 21, pp. 544. (1957) - Structural study of the Bundelkhand Granites and the associated rocks in the type area. Ind. Min. Jour., Feb., 1957, pp. 10-16. ^___^^ (1961) - The Bundelkhand granites and associated rocks from Kabrai and Mau-Ranipur areas of Hamirpur and Jhansi distts., U.P. Punjab Univ. Res. Bull., 12, pp. 10. ___^^_^_^___ (19 71) - The crystalline axis of the Himalaya - The indian shield and continental drift. Tectonophysics, 12, pp. 433-447. Schaller, W.T. (1912) - Mineralogical notes. Ser. 2. Bull. U.S.G.S., 509, pp. 89-100. Schraalz, R.F. and Swanson, F.G. (1969) - Diurnal variation in carbonate saturation of sea-water. Jour. Sed. Petr., 39, no. 1, pp. 256-267. Schmitt, J.M. and Thiry, M. (1987) - Uranium behaviour in a gossan type weathering system - example of the Bentholene deposit. Bull. Mineral., 110, pp» 197-208. Secor, D.T. (1965) - The role of fluid pressure in jointing. Amer. Jour. Sci., vol. 263, pp. 633-64^. Senin, Y.M. (1970) - Phosphorus in bottom sediments of the S-W African shelf - Lithology and mineral resources. Consultants, Bureau, N.Y., vol. 25, pp. 8-20. Shangqing, Z. (1984) - The geological features and the tendency of the evolution of the stratiform phosphate deposits in China, G.S.I. Sp. Pub. no. 17, pp. 201-206. Shapiro, J.L. and Brannock, W.W. (1962) - Rapid analysis of silicates, carbonates and phosphate rocks. U.S.G.S. Bull. 1144-.A, pp. 1-56. Sharma, V.P. (1975) - Note on the stratigraphic classification of the Parana rocks of Bastar distt., M.P. G.S.I. Misc. Pub. no. 25, pt. 1, pp. 171-175. 476 Sharma# R.P. (1979) - Mineralogy of the pyrophyllite-diaspore sanples from Bundelkhand Central ^ndia. Ind. Min,, 20, pp. 1-5 Sheldon, R.P. (1959) - Geochemistry of uranium in phosphorites and black shales of the Phosphoria Formations. Bull. U.S.G.S., 1084-D, pp. D83-D115. (1964^3) - Palaeo-latitudinal and paleo-geographic distribution of phosphotite. U.S.G.S. Prof. Paper, 501-c, pp. C-106 - C-113. ^^^^___^^^ (1964.b) - Exploration for phosphorites in Turkey (A case history)'. Eco. Geol., vol. 59, pp. 1159-1175. (1966) - Phosphate deposits of India - their discovery, geology, potential and proposed development. U.S.G.S. Tech. Letter. Phosphate-I, pp. 8. (1980) - Episodicity of the phosphate deposition and deep ocean circulation - A Hypothesis. SEPM. Sp. Pub. no. 29, pp. 239-247. (1981) - Ancient marine phosphorites. Amer. Rev. Er. Planet. Sci., 9, pp. 251-284. ___^^^^___^ (1984) - Ice-Ring origin of earth's atmosphere and hydrosphere and Late proterozoic - Cambrian phosphogenesis. G.S.I, sp. Pub. no. 17, pp. 17-22. Sholkovitz, E. (1973) - Interstitial water chemistry of the Santa Barbara basin sediments. Geochem. et. Cosm, Acta# vol. 37, pp. 2043-2073. Sillen, L.G. (1961) - The physical chemistry of sea water. In oceanography (Ed. M. Sears). Amer. Assoc. Adv. Sci. Washing D.C. Pub. 67, pp. 549-581. Silverman, S.R. et al. (1952) - Quantitative determination of calcite associated with carbonate bearing apatites. Amer. Mineral./ vol. 37, no. 3, pp. 211-222. Simpson, D.R. (1964) - The nature of alkali carbonate-apatites The Amer. Min., vol. 49, pp. 363-376. (1966) - Effects of magnesium on the formation of apatite. The Amer. Min., vol. 51, pp. 205-209. (1966) - Apatite and octa calcium phosphate - t;ffects of COo and halogens on formation. Sci., vol. 154, pp. 1660-1661. 11 Simpson, E.S. (1971) - The geology of the s.W, African continental margin - A review in F. Delaky (Ed.). The Geology of the East Atlantic continental margin, 4 ICSU/SCOR Working Derty 31 Symp. Cambridge, 1970, Inst. Geol. Sci. Rept., vol. 70, no. 16, pp. 157-170. Singh, N*N. (1988) - Tectonic and stratigraphic framework of tne lead-zinc sulphide mineralization at Zawarmata distt./ Udaipur, Rajasthan. Jour. G.S.I., vol. 31, no. 6, pp. 546-564. Singh, B.K. and Subramanian, V. (1988) - Water and sediment load in streams draining Mussoorie phosphate mining areas. Jour. G.S.I.# vol. 3, no. 6, pp. 575-587. Sinha, R.K. (1984) - Rock^phosphate - A source of multiple minerals. Chemical Age of India, vol. 35, no. 7, pp. 421-422. Slansky, M. (1979) - Distribution of uranium ani phosphorite of its concentration in sedimentary phosphates. Uranium Deposits in Africa.Geology and Exploration, 1979, pp. 239. (1979) - Repartition et possibilities de concen tration de L* Uranium Dans Les phosphate sedimentares. Geology and Expl., 1979, pp. 239, Snimov, A.I. et al. (1962) - Experimental data on the possibility of the chemical precipitation of phosphate from sea water. Gosudarst. Nauch. Issled. Inst. Govnokhim Syr'ya Trudy no. 7, pp. 289-302. Smirnov, P.L. and Entin, A#R. (1975) - Geoahemical relation between gold and phosphorus and its ln5>ortance for prospecting for gold on the Aldan shield. Geochem. Int., vol. 12, no. 1, pp. 89. _«« 3^^ NOvgorodov, P.G. (1976) - Conditions of formation of the Seligdav apatite deposit according to experimental data. Geochem. Int., vol. 13, no. 3, pp. 194. Smirnov,V.I. (1976) - Sedimentary deposits. Geology of mineral deposits, pp. 456-459. Smith, J.P. and Lehr, J.R. (1966) - An X-ray investigation of carbonate apatite. Agri. Food Chemistry, vol. 14, no. 4, pp. 342-349. Soni, M.K. (1984) - Lithomorphometric evaluation of drainage basins in Central Narmada valley, M.P. Rec. G.S.I., Vol. 113, part-G, pp. 86-98. 8 et al« (1987) - Vindhyan Supergroup - A review. Purana Basins of Penin. India, G.S.I. Mem. No. 6, pp. 87-138. Sornein, J.F. (1980) - Alteration supergene de mineralisation ferriferes. Les chapeaux de for dugiscement de siderite de Batere et du gisement de pyrite de saint-Bale. These Doct-ing, Ecole des Minesde, Paris, pp. 150. Spencer, C.P. (1975) - The micro-nutirent element, in chemical oceanography, 2nd Ed., vol, 2 (Ed.). Riley, J»P« and skirrow, G., pp. 245-300. Srikantan, B. et al. (1969) - Geology and preliminary assessment of the Birmania phosphorite deposit, Jaiselmer distt.,Rajasthan. Jr. Mines Metals Fuels 17(4), pp. 109-113. Srivastava/ J#P. (1951) - Mineral Investigations by G.S.I* during field season 1951-52, pp. 1-7. ___^_^__^ (1952) - Rocks of probable Bijawar age overlying the Bundelkhand Granites in Tikamgarh distt., M.P. Rec. G.S.I., vol. 86, pt. 4, pp. 50-85. srivastava, S.B.L. and Dwivedi, C.S. (1975) - Unpublished annual investigation report of Jhamarkotra rock phosphate deposits, Udaipur for the year 1974-75 D.M.G. Udaipur, pp. 60. Srivastava, R.N. and Hasan, S.E. (1976) - On the sedimentation and origin of Subathu phosphatic limestone around Dati area, district Mahasu, H.P. Him. Geol. Sem., New Delhi, Sept., 1976 (I), pp. 52-53. Srivastava, R.A.K. and Mehrotra, M.N. (1980) - Stromatolite associated with Semri sedimentation. Son valley region, India. G.S.I. Misc. Pub. no. 44, pp. 284-289. srivastava, N. and Banerjee, D.M. (1981) - Apatite crystallite size of Precambrlan phosphorites of India. Bco. Geol., vol. 76, no. 1, pp. 193-194. Stdrlnsky, A. et al. (1982) - The incorporation of uranium into diagenetlc phosphorite. Geochem. et. Cosm. Acta, vol. 46, no. 8, pp. 1365. Stow, S.H. (1970) - Arsenic in phosphorite and apatite. Eco. Geol., vol. 65, no. 1-6, pp. 65-67. m Stralchov, N.M. (1963) - Climate and phosphate accumulation. Eco. Geol. U.S.S.R. in English, no* 1-2, pp. 1-13. Stumm, W. and Leckie, J.O. (1970) - Phosphate exchange with sediments - its role in the productivity of surface water, in advance in water pollution research, vol. 2. N.Y. Pergamcn Press, III, p?. 26/1-26/16. (1972) - The acceleration of the hydrogeochemical cycling of phosphorus with discussion. In the changing chemistry of the oceans, ed. D. Drysser, D. Jagner. Water Resources, vol. 1, pp. 131-144. Subramanian, v. (1976) - Water chemistry of St. Lawrence estuary. Jour. Hydrology, 27, pp. 341-355. (1976) - Experimental modelling of inter elemental relationship in natural materials. Canad. Min., 14, pp. 32-39. (1980) - A geochemical model for phosphate minerali sation in marine environment. G#S.I# Misc. Pub. no. 44, pp. 308-313. (1984) - River transport of phosphorus and genesis of ancient phosphorites. G.S.I, Sp. Pub. No. 17, pp. 11-16. (1987) - Environmental geochemistry of Indian river basins - a review. Jour. G.S.I., vol. 24, no. 2, pp. 205-220, Sumnerhayes, C.P. (1967) - Marine environments of economic minerals deposition around New Zealand in a review New Zealand. Jour. Marine Fresh water Res., vol. 1, pp. 267-282. (1970) - Phosphate deposits on the N-W African continental shelf and slope. Unpub. Thesis, Univ. of London, pp. 282. et al. (1972) - The distribution and origin of phosphate in sediments off N.W. Africa. Sedimentary Geology, vol. 18, no. 1, pp. 3-28. (1973) - Distribution, origin and economic potential of phosphorite sediments from the Agulhar Bank, S. Africa. Trans. Geol. Soc, S. Africa, vol. 73, pp. 271-277. (1973) - Phosphate in sediments off S.W. Africa. Nature, vol. 243, pp. 509-511. 480 (1973^a) - Distribution and origin of phosphate in sediments from the Agulhas Bank, S, Africa. Joint Geol. Surv,/Univ. of Cape Town, Marine Geology, Programme Tech. Rept. 5, pp. 94-114. et al. (1976) - Northwest African shelf sediments influence of climatic and sedimentary processes. Jour. Geol. (in press). Swaine, D,J, (1962) - The trace elements content of fertilizers - Common wealth Durean of Soils, Tech. Comm., vol. 52, Herpenden, England, pp. 306. Swanson, V.E. (1960) - Phosphate and associated resources in Montana. U.S.G.S. Prof. Paper, 400 B, pp. 13-29. T - SERIES Tarabili, El. (1969) - Palaeogeography, palaeoecology and genesis of the phosphatic sediments in Quseir-Safaga area, U.A.R. Eco. Geol., vol. 64, no. 2, pp. 172-182. Teodorovlch, G.I. (1961) - Phosphate Group. Authigenic minerals in sedimentary rocks, pp. 84-88. Tewari, V.C. and Qureshi, M.F. (1983) - Algal structures from the upper Icrol-Lr. Tal Formations of Garhwal and Mussoorie synclines and their palaeoenvironmental significance. Jour. G.S.I., Vol. 26, pp. 111-117. Tooms, J#S. et al. (1969) - The geochemistry of marine phosphate and manganese deposits. Oceanographic Marine Geology. Amer. Rev. (London), vol. 7, pp. 49-100. Tourtelot, H.A. and Cobbc(n, W.A. (1968) - Stratigraphic signi ficance and petrology of phosphate nodules at base of Niobrora Formation East Flank of Bla k Hills, S. Dakota. U.S.G.S. Prof. Paper 594-L, pp. 119-122. Trask, P.D. (1939) - Organic content of Recent marine sediments in Trask, P.D. (Ed.). Recent marine sediments, a symposium : Tulsa# Okla, Amer. Assoc. Petrol. Geologists, pp. 428-453. Trautz, O.R. (1960) - Crystallographic studies of cal-carbo- phosphate. N.Y. Acad. Sci. Annal, vol. 85, pp. 145-160. 481 Trendall, A*F. (1983) - Introduction. In : A.F. Trendell and R.C. Morris (Eds.), iron-formations - Pacts and problems, Elsevier, pp. 1-12. Trompette, R. et al. (1980) - Stratigraphy and structural controls of Late Precambrian phosphate deposits of the N. Volta Basin in Upper Volta# Miger and Benin, W* Africa. Eco. Geol., vol. 75, pp. 62-70, Tugorinov, A.I. (1975) - Origin of uranium deposits. Recent contribution to geochemistry and analytical chemistry (Ed.). A.I. Tugarinov, John Wiley & Sons, N.Y., pp. 293-302, Tullis# J»A. (1979) - High temperature deformation of rocks and minerals. Rev. Geophys. Space Phys., vol. 17, pp. 1137- 1154. Turekian, K. (1968) - Oceans. Prentice jersey Hall Co. N,Y., pp. 120. (1973) - Chemistry of the Earth. Wiley Inter. Sc. Co., N.Y., pp. 130. Twenhofel, W.H. (1950) - Sediments of chemical deposition ••principles of Sedimentation", McGraw Hill Book Co., Inc., M.Y., Toronto, Lond, pp. 344-349 and 517-524. Tyrrell, G.W. (1980) - Phosphate deposits of organic origin. The Principles of Petrology, pp* 239-240, V - SERIES Vakhrameev, A^M. and Zanin, Y.N. (1979) - Hydrogen bearing groups in apatites according to nuclear magnetic resonance data and their geological interpretation. In s Inverting of cal-phosphates by phys. methods. Novosi-Nanka/ pp. 77-82. Valdiya» K.S. (1972) - Origin of phosphorite of the Late Precambrian Gangolihat dolomites of Pthoragarh-Kumaon, Himalaya, India. Sedimentology, 19(4), pp. 115-128. (1984) - Aspects of tectonics focus on south- central Asia. Tata McGraw Hill Pub. Co., New Delhi, pp. 319 Vallentyne, J.R. (1974) - Hie algae bowl : Lakes and man. Fish Res. Board. Canad. Misc., vol. 22, pp. 82-85 and 166. 48E Van-2indeven,, D.E.MD.E.M.. {1976{1976V -- TThl e evolution of late Quaternary palaeoclimateess of Sn,. AfrioAfrice^ iinn palaeo-ecology of Africa, Balkema Cape Town, pppp . 1-46A Vasilieva# Z.S. (1958) - On tPie role of mancanese In apatite j All Union Min. Soc* Mem., 87, po. 455-461 • Veeh, H.H. et al. (1973) - Contemf>^ary phosphorites on the continental margin off Peru, Sci,, v«3l. 181, no. 4102, pp. 844-845. et al. (1974) - Accumulation of uranium in sediments and phosphorites on the s.W. African shelf. Marine Chem., vol. 2, pp. 189-202. Verbeeck, R.M.H. et al. (1981) - Lattice parameter and cation distribution of solid solutions of calcium and lead hydroxyla- patite. Calcified Tissue Inter. 33, pp. 243-247. Verma, K.K. and Barman, G. (1975) - On the origin of phospho rites in the Aravalli rocks of Udaipur, Rajasthan, India. Sem. on Recent Adv. in Precamb. Geology of Rajasthan, UdaiBur, 4, pp. 43-45. (1980) - Mineral deposits related to stromatolites. G.S.I. Sp. Pub. no, 17, pp. 303-307. Vinogradov, A.P. (1953) - The elementary chemical composition of marine organisms. Sears Found, Marine Res. Mem. 2, Yale Univ., pp. 647. Viqar, H. (1981) - Mineralogy and origin of Birroania phosphorit) deposits, distt. Jaiselmer, Rajasthan (Unpub.), Ph.D. Thesis, pp. 181. W - SERIES Wadepohl, K.H. (1969) - Handbook of Geochemistry,, vol. I and II*- "Phosphates", pp. 15-A-I. Springer-Berlin, Heidelberg, N.Y. Waggaman, W.H. (1952) - Phosphoric acid, phosphates and phosphorite fertilizers.(2nd Ed.). N.Y. Rein Hold PUD. Cor., pp. 683. m Walker, T.R. (1967) - Formation of red beds in modern and ancient deserts. Geol. Soc. Amer. Bull., vol. 78, pp. 353- 368. (1974) - Formation of red beds in moist climates a hypothesis. Geol. Soc. Amer. Bull., vol. 85, pp. 633-638. Walter, M,R. et al. (1976) - Microfossils from a newly discovered Precambrian stromatolitic iron-formation in W. Australia. Nature, 261, pp. 221-233. Warington, R. (1866) - Researches on the phosphate or calcium upon the solubility of Tricalcic phosphate. Jour. Chem. Soc, vol. 19, pp. 296. Watson, E.B. (1979, a) - Zircon saturation in felsic liquids - experimental results and applications to trace elements geo chemistry. Contrib. Min. Petr., 70, pp. 407-419. (1979-b) - Apatite saturation in basic intermediate magmas. Geophys. Res* Tjett.# 6,pp. 937-940. _^^_^_^_____^ (1980) - Apatite and phosphorus in mantle source region t an experimental study of apatite/melt equilibria at pressures to 25 Kbr. Er. Pi. Sci. Lett., 51, pp. 322-335. ___^______^ and Capobianco, C.J. (1981) - Phosphorus and the rare earth elements in felsic magmas - an assessment of the role of apatite. Geochem. et. Cosm. Acta# vol. 45, pp. 2349- 2358. Wey, R. et Siffert, B. (1961) - factions de La silica mono- moleculare en solution arec Les ions Al+^ et Mg"'"'^, Genesect synthesis des argiles. Coll. Intern. C.N.R.S. - 105, pp. 11-23 White, A.J.R. et al. (1977) - Geology of the Bernidale, 1 : 100,000 sheet geological survey of New S. Wales, Dept. of Mines/ Pub. no. 8625, pp. 138. White, B. (1984) - Stromatolites and associated facies in shallowing - upward cycle from the Middle Proterozoic Altyn Formation of Glaciers National Park Montana- Precamb. Res.,, vol. 24, no. 1, pp. 1-26. Wiebe, W.J. (1987) - Nutrient pools and dynamics in tropical, marine, coastal environments with special reference to the Caribbean and Indo-West Pacific region. UNESCO Rept. in Marine Science, no. 46, pp. 19-42. m Williams, D.H. (1852) - Geological surveying of the Sagar distt., M.P. Rec, G.S.I*, vol. I, pp. 1-15. Willson, W.L. (1868 -1876) - Detailed geological mapping of Sagar and Damoh districts (M.P.), India. Rec. G*S.I. Mem. I, pp. 56-89. Winnard, L. (1963) - Etude physico-chimique de diverses carbonate-apatites. Bull. Soc. Royle Sciences Liege, physico- chemical study of various carbonate-apstites., vol. 32, po. 575-596. Winchell, A.N. and Winchell, H. (1968) - Phosphates. Elements of optical mineralogy (3rd Ed.), pp. 182-237. Winkler, H.G.P. (1967) - Petrogenesis of metamorphic rocks. 2nd Ed., Springer-Verlag, pp. 237. Y - SERIES Yochelson, A.L. (1968) - Biostratigraphy of the phosphorus Park City and Shedhorn Formation. U.S.G.S. Prof. Paper, 313-D, pp. 571-660. Young, E.J# et al. (1969) - Mineralogy and geochemistry of fluorapatite from Oerrode Mercado, Durange, Mexico. U.S.G.S. Prof. Paper, 659-D, pp. 84-93. Youssef, M.I. (1958) - Association of phosphate with synclines and its bearing on prospecting for phosphates in Shan. The Egy. Jour. Geology, vol. 2, pp. 75-87. ^ (1965) - Genesis of bedded phosphates. Eco. Geol., vol. 60, no. 3, pp. 590-600. (1970) - Palaeogeography, palaeoecology and genesis of the phosphatic sediments in the Quesseir-Safaga areas, U.A.R. Eco. Geol., vol. 65, no. 1-6, pp. 150-152. • f . , ^_ ^ 485 CO S I- C ' M lf\ •— , 0 2 f C^ Q -d- 0 IfbN ro rbo bro 0 ro ub> P >• ^ w V » ^ •V :3 •*» 0 2 *• CO ITN S f S ' S f •w t r *" s < CO 0 rn J- J- 0 0 0 0 0 H T-4 w M ro « b CM CM I-* •• OJ 0 CM •> J" ^ ^ « g Q^ rH 1-1 i-« r4 rS C3N a2: 0 0 0 0 0a^ 0 0 0 0o-^ 0 0 c^ 0^ 0 ON 0 a^ C7N 0 CO -5 t>. r^ i>- C^ c*^ C^ c^ C^ r>. pa o 4) 0) CD T? CO x: £ E 4-* CO 0) 0 E C x: U 0 'O •r^ I^ x; •H •4-' V-l U c ex •0 •H -*- c %-» CO CO C ;n CO 0) •^ 0) •c 6 CO a3 x; T) 0 T: 0) a: (L> M •H -H •o 4-* a> 0) x: QC4 4-> CO +' :Q f* j::rH xi •M +-» CM (^ :n ti0*O -•-» « 4) ^ *) Ci, TS (0 -u •H 'O 0) TS 3 CK4 M ^-3 0 c a« c •0 OS -H V-( 1-^ -H 0 •M CO CO S c 0 E 0 n r-l o 25 0) X r-l J: t4 CD U 4) 4) «> 0 H tt> 0) CD 0 PC 0 s a> a. E a • £1 M a>x: +^ 1-1 (4 -M <1» H o M 0 6-1 \ CO > << (X 0 Ct4 ^ g 0 i-i M • -a CO tH CM ro J- ir\ vO l>. CO a> -t~~t »—/ -X ^j c^ U"' r-i 35 m a^ LTN rH \rs ro J- c% rH OO OrH X* • « \o ^£) so • • • • • C 01 • rH rH • • • 0 rH 0 r-{ 0 ^-^ Gl 4-1 JC 0 TH 0 JO O^ 0 0 0 0 0 r^ iH ON 0-' O-x rH rH rH rH r0H 7+->^ » 0 lr\ c^ rH m CM rH rvi CT^ 0 TH x> '-0 00 c^ ro CO ro C^ OJ « • * • • • « • « • • 0 rr iH CM CM 0 rH 0 rH rH r-( 0 rH m LfN t-i 0 rH lr\ rH 0 J- 0- rH 1-1 -n 0 00 CM 0 TH 0 0 0 0 * • • • • • • • t^ • • • r CNJ 0 0 CM 0 0 0 CM 0 H rH ro CM rH ITN ir\ 0 IfS 0 CJs 0 sO ro 0 ri 0 0 rH ON 0 o- r-i D- •30 ro CM r* 1x4 0 ITS CM \r\ ro \0 X> J- CM Ifs CM 0 C3N CM CM rvi rH rH r-i ro ro J- ro 03 =K.^ -:r S4 1* ^ • r.5 lr> t-4 •x> ro rH C^ m no ^ ro 0 0 CM c^ JO 0 CM ro TH r^ UN PH • • • • • Ut • • • • « 0 t-H TH rH 0 rH £-t 0 0 0 0 0 CJ OJ C a: •<\ id TH M CtJl 0 ON iTv ir\ r^ rH UN O^ C^ -^ 0 5 •^ t-1 m VO 0 •X) ru CM rH 0 tM 00 M 0 m OJ CM CM CM rH r-i rH 0 0 0 0 0 EO 0 i-H ExI a 11 << Q m UN ir\ ir\ m 0 ro r-^ x: xO JO 0 'D CM r\i 0 y a, § • • • • • U • Ut u « « en 2 TH 0 r-i 0 0 tri 0 H H 0 0 0 :z1: i* CO a, g CM ir\ rH C3N CO m ir\ sO • C% 0 '^ 0 C^ CM r^ CM z ^ rn # x> • • • 00 • ^ rH 0 ro M X 0 0 • iH M 0 • J- • • • * M CM •<—1 a- rH TH t-t OS rH 00 rH ro C*^ S PC ^-N 4) r^ 0 ^ X4 M Q M c^ ir\ 0 ro 0 0 J- r^ ::? c ro m a> CM 0 ^>D CM CM J- B •H • • • • • • • • 14 • u CQ n0> -w* 0 0 0 0 0 r-i 0 0 0 frH 0 £H M cc bO PC < s ^o t-i tH ru rH T-H x> C^ 0 r-i C^ CM CM cn C C3N .AJ 00 0 AJ 0 JT T^ 0•^ J- M s • • • • • « • • • » « Q 0 0 0 ITS ^\1 m ^o ^ r»-\ 0^ OD -J- 0 K CO ir :M ro ro CM ;M AJ J- J- -d- J- ^ CO 0 :-> .-M J- 0 0 m 0 r-! ON W 5 r-t ^H rn CM 0 rH 0 f^ ts 0 • • • • • * u u • • U s <; 3 J- 0 0 0 0 0 0 tH H 0 0 H •J *-3 J:; f^a HH oa @ CM IfN CM ITN rH \D 0 CM J- •^ 0 J- 0 (T- J- SO 0 0 0 << •H « • • • ^ • • U • u « s: ^ rr 0 0 0 0 £-* 0 r~i H 0 H 0 •-H rH JT J- Ov ro J- M ro 0 0 0 ON 00 0 XfS 0 OO CM 0 C^ rH 0 0 ON • • c*^• • « « 1 CM • • • • • 0 r^ rH irs sO sO -1 CM \0 UN ITN C^ SO r^ M '< J CQ 0 X> CM ITS ro C^ 0^ t-l r^ ^ ITS < 1—1 0 m 0 CM 0 CM CO 0 0 0 ir* CM • • • • • • • « • • » 0 rvj ^^^ vO m r-i CT^ Jt CM CM ro CM rvj TH rH rn ro ro :0 1 1 1 1 1 CQ CQ CO 03 1 1 1 1 1 1 0 0 0 0 0 J:: JZ J:; J5 £: x: x; x: x: J^ x: a« CL *> a. a> n. «) •a «> n. a* 4> % t» n, «> a, «> ru 4> 00 n •I-' to +j en •I-' U -M CO -M 0) -M 1 H-* 1 •*-» 1 4-' 1 H-* 1 H-* o-H 0 fH 0 -H 0 TH 0 -rH 0-r4 SS-H >»'»H >fH >»TH «::-. x: s^ x: t, -G ^* J^ ^ x: t. -c ^. u u &i: U L. t-i ^ tH t4 0 c ^ 0 a* 0 n, 0 a. 0 cu 0 ru 0 to 0 0 0 CO 0 (0 0 0) 0 XtD 1 1 1 1 1 TJ x: TJ XI •ox: n x; -o x: a> ro ro ro ro UN *H CM M '>J O € ii-\ O ON o O 487 O rn O tH r^ CM rH rH rH O CM r-l O r^ O J- m C ^ • • t4 Ui U • • *. c\j &-t O O E^ £H CH o :\j 'H o x: CO O^ no O O \0 CM o J- o rs. C^ Lr» ON ro o •j^ « • • • • • • • [> LTv •o O' 00 NO \r\ ro o.-NJr ^H r\j CM CM CM CM rvi rH CM to. TH -J- r-i x> CM CM rH o rv C^ C^ ^ LTN rH O CNiO • • • ^ • • • • O o o tH O o rH rH J- rH rH rH ITS ITS rH ro o ^ m :M no CM .-M ro J- CM • • • • • • • • Q 0^ o O O O O O O O S ^ 00 r-i rH CO •O rH M O C\J J- r<0 Jt ro ro vH r-t «; • • • • • • • • ifc X) o o O o O O o o r-i o rH -^ m r^ O o C^ o O UN o • • • • CM # • ro N r-t ir\ sO • o ^ • 0) r^ rH rH r^ O^ rH 1-t X> it. s r^ ON O^ CM o UN ru rH O O m ri \D rM ON o o • • • • • » • • to rH o O o rH r^ o r^ S ^0 r4 ON Aj o o o ir\ O^ O r-t LTN O ON rH o o o u% rj rn O- \0 NO c^ ro r3 rn ro ro ro rH ro m rH O O ro O O r-4 rH rH rH rH 3 J- • • IA • • « • U uc O O cH o o o o H -M m i^ ^ o o ro O O CM o ir\ U^ Jt •rt ro • * u • • * « (H ^ o O ^ o O O O El m xr\ ON JO CM o vO ON rH c O CM o> ro o rH rH J- ^ CNJ rH o rH CM ro vO CM •^ m rH rH CO O^ Jt CM O M 00 O ro ON n UN ro D^ o •H tH O r^-^ CM o- T-i o rH CN :i3 CM :M .M TH CM CM J- ^M 0) Q> ^ 0) a> 0) (1) <1> 1 +-• 1 -M ••-' 1 +-' 1 +-» 1 -M -*-' •*-» a> •H 0)^ 1 -ri 0) -H 0) •H 0> -H •H -m CO c (H C tn « tn c U c u C*4 t^ 1 t^ ^ *^ o O O O C O o O o o o o 1 (0 O 1 tH Q o ^ •^- JS •^^x: OJ:; +-' J:: H-' x:. H-'X! N-H x: N -H J:: o c CQ tx CO Q, w o. n nu CO n. «Q O. 4-' O a. -*-' O c. X ;3 c CQ c n C 01 c CO C 60 C (0 u o n u o m o O O o o o o o O o o o o a> o (0 0) O u x: r-iX: UJZ t~, s: Ci js lux: £) U ^ =J tij;: ^V M o. M CL v-t^ V-* CL »-H a, n (X GT^ a. oro:: % o. • E en o o M no -:r UN ^ c^ 03 a- inz I '-I rn E>- .4- J- O Jt O m T-t .-M TD'-* m * * • • c cu o r-{ *-4 ON <^ i =1 -M o o o ON 0^ ^ rH rH 88 m r-i ON xrs rg O o u^ m o nn • • • A • r^" T-( 'M O c-t T-i 1 o *H O rO O CM O +Cv i CM u • (^ * • X ri tr* o ir^ O O xO o ro lf\ ITN ir\ m ;M :o ro ITN • • • » • o ^C X) ao r^ l>- Cvjrl -CM cu TH t-i CM i O, ^ 1 r-t CM c ITv ON o r-i ro LTx ^ m r\JO • • « « • U: -rH ^-t r^ r-l CM CM rH CM ON ir\ r-» o CM ITN TH CM m I CM • • • • « 1 CS o o o O O 1 ^ ON ON r-i CT^ O^ rH 1 o r-t O t-t CM CM ^ • • • * • ;>:. JO o o O O O :0 rn o ,-M sD O CO O r^ r<> NO * o CM • • • o • 4J r^ X r^ NO rS x> O^ -M J- O \r\ m C7^ t>- X> NO o « • • • • o O O o o CM ^ o o CO ro cr^ o o ON o • • • • • OJ ITN \D O c^ NO o O :i- CM o CM \ o o t-t T-» 3^ • t. • t. • X o i-i o 6H o CM o o C^ ON O J- u-\ C^ T-» a> •H • ^ « • • o 03 C7^ (^ o e-* o o o ro rO rO o c^ c^ n O <> CM J- ON ro u CM • • • • • b-1 1-1 -M r-4 IXN NO ri CVI ON rn 00 \0 o ON C^ ITS o C\JTH O iH o ro ON J- ro CM UN r4 O o o o O 6H o O -J CVJTH O O o O o o o o O O o ro ro a CM O •O r^ NO ro o o o o O O o O O ro NO CM O ON ro rvj rn ro o "VJ ro -4J CO uX o CO O O o :M M o O O ro o O 5 0) eg rNJ ^ I no ON M3 ro X> ON o ro ro ro CM M rvJ ro o ro ro tXN O rg <-i <-< J- O o r-i O O "^ O o ^ 00 :0 ITN ro XTN ro AJ r-f o O 00 -^J 03 sO UN o no • . CM UN UN O o O »-* • UN CM 5 t-» t-i o vO O ON M Ai Al O o ro • * O o o o Q -M ON c\J CM ITN o rO UN O o » ^ o O o o ON ro o o rH o CO •• o ^o UN o ON ON o M O X CM Cd O o CM ON a r-4 UN .NJ o \0 ro m UN ON o O o X) UN TH ' O o rO ro O^ ON o MD \0 o \0 UN 0- .^ a) H) o Oi 0) O o 4> w Q a> o ^ ^ » ^ OT •r-t 03 o c c c c c c c c C c ir^ C 50 c ^ CO a: ^ CO m CO cu CD 0) C3 ^ CD 0) I u u o o a e3 00 00 O w o o 0) o I I I E to X) o .NJ J- U\ \0 CO O \ CM AJ CM -M ro ro ro ro zn r:i I m ro o 1 o c^ 1 ^ CM rO r^ sO sO irm\ 1 ro * • o OO • 0 • O o• o o C o • • O 'X> t^ c^ OO CO U O^ -H T-oI o^ O o^ CJs OS OS TH o 490 U^ J- a^ J- OS so c^ o CO T-* o o o \0 J- r~i o CVi • • • + C^ m -:i- p:3 CO -^ O J o 00 r^ rH C3S J- S4 J- 0^ • • • E-» • • o• o O O CM o o o o o O irs o O so o o ir\ IfS :M C:s O OS xrs o \r\ J> CVI o O o O O UN CO CO if\ J- « \r\ o v-M • • • CM O o o o CD 0\ J- CM x> CM CM GO o O C7S rn CM t-l sO • » • O ^o tH <1> CO o o ^i^ OS r-i CM CO Os J- ro TH \r\ O ^0 O • • • I rn • r^ o o o OO CM* CM M rn o tH o C3S rn o J- • • • CM -J- TH sO o o U) NO t-i tH T-i CO so •>o •H o \0 • o \0 « • • o o CM O o ITS ITS 03 \r\ rn m o f*^ r-i so so • TS r-t TH O • • • :3 J- o o o o o o o CO o so tH CM r*- • O r^ CM tH O • • • o O O o CT^ o o iH OS O J- rn J- • & CM CM ITS \f\ o• • CM rH OS \0 CO O •sO rn TH r^ CM o J- O o CM CM <3s O • • • • * •H X) • vO J- CO t>- CO GO c^ so ro CM CM o I I w CO 4> 03 0) D C 3 C I o o o o o o o c o 5 4) +^ 0; 4-' O CO C CQ TO 4> •c ft) tH A) CO a> •H «> *r^ +-» -H •*-» rH E rH e «^ B CQ K^ CO 1^ CO h-:) o. • B « to o I 00 OS O CO :s I rn 3- so ^-1 ^ O CM CM Cs- J.x>- O cC^N O • scO^ • • O • c O • CO • oo ca CO 00 00 CO 0^ o ON C7S J ToH t-oH ON o a^ 431 OJ o rn CO U\ sQ sD ir\ o ON sO c^ ir\ r> O ON o * • • * • « • so so CM ro ^ CM TH O ro o ^ CM ^ J- C^ r»^ m O ' • • • « • u CM o o O O o H O \0 so o t>- O o o O o O o rO J- XTN UN CM CM O o o ^ r4 CM CM \rs O \rs O xrs o o rn CM CM CM CO J- J- ro o- (0 O CM J- Jt CM ^ o o N^ o CO CM UN 0) 00 o• o• • 0 t4 • o CM O TS H o ro CM ro CO J- us TH Cs. Jt CJN O so ro r^ oo O CO CM CM • - • • • • * rn O o o o ON o •CO JO OS ro so JT a> rH J- UN O^ ro 00 \0 c>. o ITS • • • • • • CO so ro ro CM UN 00 :M OS CM CM CM tc>H . CoM rH T-* O J- CO ^ sD SO O 1~\ o ITS SO sO US sO O OO C7N o• « • • • • ^-M ro \0 so NO ^ UN sO UN UN Ua-N UN CM UN \fs OS O CO CM UN 00 UN Cs. o rl »H rn * o ro no o O CM 00 \0 ro u^ O O UN o CM 'fi ro ro » O ON J- CO sD UN ro CM o CTN CO O sO ro • CM \D UN CM CM SO CM ro J- O o sO GO sO sNJ ro ro ro CM ro UN ON UN CM • • 00 sO sO ON ON sO o CM C7N CM to I I I I I I I I I CO 0) O tt> O 4) O 4) O «) ifi o c -r* C ^ C ^ c ^ c •H C f-t C •H C -H C o o -^ O -*-' O •*-» o +-• O 4-* O -M O +^ o ti .^ •*-' O •4-* O ^ +J 1-1 •*-• 1-1 •»-» O- C o w E w E 03 B CO SO £01 CO S CO o o o o o O 4> O ft> o a> M 4> ^ a> r-i E r-* H -H a i-* B r-l E o a> ^ -rl O-H O Ti O -H O-rH O ^ O -H O-H .-I B 0) Q»-5 Q^-5 Q^^ O -H r-i a .• E to CD O US NO CO O CM J* CO ;s; UN Us Us VTN XTN JU x-' *^ C7' Ol tH c^ ro ro ^ tH tH ^ iH CO TH o m ro c^ CM CM iH •^-0 NO C^ ON • CN- UN rH -7N •D i-t o • C 03 O (JO O O ON O O o ON CO ON CO • CO 00* -^ CO -t-* o ON O O ON O O o O- ON O' ON CO ON ti O •H t-i r^ iH iH tH ON ^ 0 OH \o OO o -J- CM -d- CM CT^ ro UN ro Cv o UN ON P c^ m t-» t>- CM t>. NO O tH ro ro O J- ro UN O C4r-i ;^ CM o CM O o H o o O O o o sO c^ O ir\ O CO -^ m CO H CO tH CN C^ ON O^ cMv^ o o c^ o r*- ro o ro c^ o J- Ou *"* • • « » « • • (4 t4 P • Vl « • • o o o o o O o H H t-f O cH o o o ir\ TH ro o o o O O o O ND NO O O rvj no CJN UN UN k/N UN o CM CM o o 8 r\)T-t tn ti • • • • • • • • • » • * • !«:! £-4 E-t T-i O O o o o O tH O o o o C^ O ir\ lf\ ITS o ITN ir\ o o UN o o UN o Ol UN 1 CM CM CM r m ^O ON o- C^ CM tH ro O c\i rH l>- CN. 00 CM NO o C^ UN m rv* ro NO £>. C^ ^ CM TH tH CN. fH CM CM t-i o if\ r4 O C3N tH O o VH tH o CN- o O NO tH NO 'JO c^ CM o 00 tH O o c^ IfN NO rO OO J- NO CO (H ON NO o tH • • O • • t^ u » • • • • U • « « o -^ 60 ^O ro xO t-i H TH CM \fS ro ro t-t CM iH r^ CM tH s: ro J- J- sO O ON ."M c^ UN J- CM CN. o 00 ON O o ^ oo ir\ O 00 ON NO ON ON CM tH ^ ON • 2> O VTN o » '3 O O O T-i O tH O O UN O tH UN o -:*• CM O c^ c^ NO M C^ -d- tH ro 00 J- NO CO O CM o TH CM TH vJ3 CM r-t tH -"M O CM CM fH tH -CM TH 3 J- 2Z O O o O o O O O O O O o o O O CM C^ CO ^ J- D^ ro iH O rn T-l r-- CM JT CM iH CM Jt -ri • u jt • • U u • u u • u • U • sr* &s • O tr* £H e-t 6H O 6H iH EH o o o o o ro \r\ TH CO CO ro CJN ON NO c^ ro tH o UN tH o -:f ON ITS ^ vO UN O^ J- CM CN. CN* Nf) CM ON CMCM p • « « rH CM J- IfN NO IfN rO o TH TH J- H en CM ^ tH iH tH ON CO ro CJN ro o rH NO V^ C^ tH ro NO O CO CM O O ro ;M O 00 ^£) tH CTN CN. «H CM o O OO rn o vO ITN ON CJN o vO c^ ON ON 00 CM GO CO OO CO 00 CO CN- CO ON CO 00 CO CO NO CM NO CO 1 1 1 o o O 0) 4) 0) 4) Ov X) 'H jt ^:o o^ O O NO c^ UN T-H O TH o ON ON ON O N£) J- fH NO rH Jt • • • • • • • • CMCVJ rO rn r~i rn rH ^ O O OD rH 1 IX: rH • o O o rH 00 ON J- 1 J- CO TH O J- ro ro 1 ir\ ON rH CJN O ^ J- ro rH ro O O 1 C TH CNJTH o o o O o CM rH rH O EH EH • i % -t 1 o ro X) rn r-i O o O NO NO O NO o o rH CM CM CM O O U^ o o J- J- X) o CM • • • • • ro • 1^ • * • • ^ ^ J- \o CM o o o o o o d d o ir\ CM rvj UN o o UN CM Al O CM o o ."M J- UN rH CM r^ ro © ON • CM rH • • • • • • • • • s rH o o o o o O rH rH O o d o O Ol CM O 20 CM o J- NO IfN ON O^ CO CM o o * CO ON CM sO sO . • • o so • • • • • \0 UN ro • • CM O i-f ro ro rH • rH rH CM -o O J- O rH _4- •sO o O- rn ON rH rn M rH O U\ o-^ J- X* C\J M T~i • • • • « m ro OO CO CO NO . ro 03 • '-0 C^ JO TH « • « • • • it, UN GO LfN CM rH CM CM ro rH o rH :0 rH ON O rH NO O^ !>. O o. OO CO CN. X) • ON • rH 'X3 ro ro CM O NO O CM o • rH * • • • CO • rH CNJ rH • • s ^ c^ X> ND CO CO ro CM ^ CM CM |"0 Jt o m m -Nl C*^ rH CM X) no UN CO 1 O o Xi fo rvj t-i • • I>. C^ M C7N CM rH rH o • • • o ^o o O rH t-i CM O O rH O rH d O AJ ir\ ro c^ CM ON J- CM C> O o CM o »-H rH CM T^ rH O rH CM -M rH X J- CM • • • • • • * • • » ro o o o o o o o o o o O • d O • CNJ Xf^ \D UN CO UN o '^ GO sO J- 4) O rH r*- CM 0^ -If J- CM ON ^O rH o CD cH ro CM J- t-H C\J o o O CM rO r\J EH £H ir ro C^ ON f^ J- 1 O JO UN CM CM rH c^ rH ^ CNJ • 00 CH • • O CM c^ CN. ro r-l CM \0 • • & ON rH r^ rH * * • • -^ oo u\ ro CO CTs rH rH CM • • rn CM' CM CM O ON OJ ro o o O X) X) rH UN ^X> C3N rH ON CM c^ sD CO 'H • • • • • vO X) CO • * * • • a' ro J- UN c^ .:0 C3N • • • C^ -^ rn U^ rH rH CM 00 oo CO CQ d) 4) 0) 0) 0) C C G c O O o 1 CO O-H t -M *• +^ o o 0? OJ 4) H-" o c 03 m CO en n r-H r-H t-t -1 C C C to CO CO CO O O O CD V c c x: -C a> CO CO CO CO CO CO 1-1 CO M IH l-H cypQ CO CO Q. • B m rH UN o cy m -:*- NO r^ OO ON r:) «H «> O C^ rN. tv t>- r^ r*- o- c^ c^ c^ x> GO 00 c^ O o o 4-J • • • • CM J- vU ? 494 TH TH H O 1 1 1 1 ro CM C^ vO v_^ CO rW ru o^ c^ so rn O CM rn o o sO • r-t • ^ ^ r-^ 1 • 1 I o o c^ OS ra 1 o • u • ro o H o O to SO CM TH OS CO O -± ITS ON o * • • • ITS CTN C^ CO ro -d- ro O t t I C^ CM O^ U\ o CM ^ *-* Ov • « • CM O CM a o CM Jt ro \r\ M !^ zsi OS ro n • OS ro O ro <-i 1 • * ro O O o <4 O 1 1 I O » U %^ u % o £-1 H EH CO X O a: O ITS O O OS O ITS • • • o ^ O o 03 CM 1 1 f t O rn •H Hu £-u* EuH r-4 o ro sO • CO r-* 0^ o • • • 1-4 NO ro sO 01 1 1 1 I O ^ CO O CM o V\ OS ro CM o CM 5 <5 ITS 1^ o CM 05 cc o OS ro O o • CM CTv ro • f CM CM I I I O CM oo ITS -H O CTs J- CO • • so CO < O CO -^ a r-* ex a n t, CO to o o o o CO O 6H A CD cofv us: ^ • CO t dj o rM co» ro 495 ITS TH CO JO O • • r-i C\i T-( CM* 1 1 o ON IfN CM* c^ I 1 -XJ l>- • • OJ o o Eri Co5 vrHn CO O TH ro o 1 o rH ^ :M • • • O ro O o o 1 1 1 • ^ t^ SH o ru o H H E-t > ^-t oi W lf\ ro O O o X) Cv. ro • • • • UN CM ON CO CM J- CM CM 1 1 1 1 o^ O o^ CM c^ t-( ON ro ir> • • • • O rH J- CM IfN ITv CU T-i iH rn CM T-l o^ UN UN OO • J- C^ C^ M a o1 I rH rr^ • 1 r-i o1 o ti • CH CM en O E-i \r\ CT^ CM ^ X) * • • CM O O O 1 1 I I oC M IfN CO ON c^ CM iz; o• o• O CO ON CM rn ON • CM NO o o t t o o t CM o OJ oo EH E-1 O o o I 0) O 0) to tn I +-» 0) -H O 4) CO O o c o c I O I IH TD x; -»^ J:: Q> O « ex O CO » a. Co CoO o o u x: CO O 03 03 o CO ^^ .NJ rn ITS in X) o o O o o o o O O o o 496 TO Q o i 03 O c O o I ro EH PCi 33 C O ro Q ON o (0 1 a ^< oil O > CC a o a* NO ON ITN as o £-* O a a> o w 03 U^ ir\ CM CO 4) o I B\a a a, c' :25 JO O^ (4 m 6H sO \r\ fH »-i ir\ rvj CO O^ nn £H C\J C\J 00 ITS m ON T-l m rM r\J t> cvi ^o ^ ir\ c^ ao rO r^ rH ^^ T^ ON H QC OJ 1-H O \r\ O- CM ON O^ ^ vH -:^ ON o 1 1 t 1 1 ^ CO 1 1 CO CO CO 1 o 0) O 0) CO CO o 4) O 0) ^ +-* X^ -M XJ*^ o 0) o 0) x: -M XI-M O-H cu -H a. "H -C 4-' x; -M cu -H CU-H O C 1 HH 1 JH a. •H ru -H t t^ t fH CC O <1> o o o 1 (^ 1 ^ <\> O V-> o m ITv \0 o CO U-\ o o CJv w t-i o a^ 1^^ t-, ON CVJ ro T-i o TD rH rH CM \r\ vO C-* tH iH CM CM tH O ON ir\ O X) o c o ro O xD ^ \0 C\4 OJ CM S) JO 6H o o. :Ai N ^ J- O tr-* n; o o Q t4 ON X) ON ON 33 Z o O EH o CM ro ITS O N O o LTN ON Lr\ O t* X) X) 4- 2^ t-t TH TH o 6-t tH o CT^ M o \r\ rvi rn o J- 00 P NO ITN CO U o ON ro -S E>- t-t CM ir* ro O CM t4 Q -3- UN IfN ON O CM CM •H ITN o u-s o o CM CM CO rn S ^ 1 Q 1 UN 1 »-* 1 O 1 t, IfN T-( t-t T-i o o 03 iH to CO to &^ no 1-1 1-i ITS O o O o O -G o xa:, O. fX a, ^ 0) •1) 1 1 1 » >. >* >* >» 0) •H 0) -H 4) •TH tt>^ a> -H 0} •H O -H u u ^ £H u c ^ c Li C EH C (H c t, c t^ CO d) CD V CO a> CO ro u^ 0 0 i 13 NO £^ C\J H OJ ON O ON T-< £r* TH t-l 0 CJ 0 0 ON \r\ ITS c 0 rH ^ &4 ro a NJ X) (M •H tH cH t-i s ON ON O O CM t-l o o EH CO ON z; 2; o EH o CM -fN rvi ITN ITx XTN 0 ^ J- J- T? H iH a> Q 0 LfN ir\ •x^ 0 o 0 NO 0 CD •*-» r-i ro CM f-c>i -^ tH 0 C\J H 2: 11 ri tH a H 2S ITS > CM O ON X) en 2; 2: o 0 TH T-i -H GO ON 0 so tH T-i 0 55 'H i-:f 1 ro 1 ro 1 ro t tH t TH 1 0 CO CD CD CD CD CO CD •H TH ^ -rH •H •H •H 0 0 0) 0 0 0 0 0 0 0 0) 0 0* 0) -M 0) "H -*-» (D-f-r CO rs^ CVi o- ON o- rH o TH iH o o Cvj 1-* o 1-i OD O o o o TH o o o o • • • • • • • • o o o o o o o o o ^ o^ CM TH CVI OO cr- a- o Ov H t-l ^ [>. a> rH C\J o l^^ o ir\ ir\ c: O) ^ ir\ ON t^ \r\ ToH o 1-1 (M T^ £-* UN N3 m Q no o EH J- •O o lf\ r- co t-i a a. ^ J- o T-t C\J z: 33 CO ^r\ ro ro rn Q ;2: CAJ s o O M a: ffi UN O CC O :3 X) CM ^ ^^ o J- CM CM o CO CO Q NO M OK CM 00 UN UN no iH 'X3 -^ 1-1 CM >-3 rn I NO OO ^ > c\j J" J- E-* ON H SI O UN o OO CM Oi o CM UN ON o 0) to 0) 0) OJ OJ 9> o c a> *-» (0 TH « Cz3 c c •2 -d C ^ o f-t CD CO o 1-H c^ ON u ro o (WJ o^ ON x> t -:^ en rH OJ J- TH CO O a Q Q CM o ^ 00 O ;25 Q J3 t U ON O Sz; EH ;2; IS CM \rs O « J- CM tH ^ 2: O m I I .M O CM o r^ tJN NO ^o ^o ir\ iro> TH f^ \C\o t>- \r\ roH >-* r^ ^ o CM o ro o J- ro CO .-^ tt IS CM CM m TH J- JT H 0 0 > Ci x> .:i- C^ -d- nn ^ CH <^i CM £H t-i rH J- PO C^ EH CH 0- •H 0 AJ K tH @ .^ 0 sO CM AI M .M TH 9 ro 0 CM rH ro m ro 5 -4; 1 1 1 t CO ^^ CO 0) 0 OJ 0 (D 0 OJ 0 .-\J m ir\ O (AJ X) CM X> c^ o J- O -X) Jt a- .4- r-i OJ cry TH r-i rH T-l 0% O rM ON O x> ITN lf\ P Q t>- ON rvoi r\ CO CM t-* 2; r-i CM E-i a Q O Q Q CM 25 3 S 2: !2; no ^4 MD o Q K s; 2; £5 CO ON la UN o C\j t-4 CM 25 25 O =3 J- CM \0 m x> T3 0) o o CVJ irs lf\ o ^ rA •CO fn SO SO o C3 rn 6-* CM r^ H C^ TH UN o 03 o cH tl II &4 o CM OO sD O 2: > C\J OO •,o ro sD ro t>- ITS C^ rH sO rH rH H rH CV -± -H J- X> Us !>- C^ m o ^ n. T-K 3 rH US J- O m UN J- us rO 1=3 CM o 1 t s o M ca •H UN V? PO o O I I I ;2; H 1*4 rH o CO > '0 CM CM O no CM rH o I I I I !=> J3 Q Q Q -J? .3 o O <:o ON CM CM n I I I a CO Q UN o rn O a* 4- UN UN CM o o H o O ON O CM o o I I I o o Q I I EH I en "3 -3- oo UN rn C7^ no o o 00 J- O o o rn 1-* o o O Q t3 o o Q s O CM CO O C7S rn vO o I I I I U 6H CO CC [a UN O^ rH o UN UN O \D NU CM r^ ro rH H a CM ^ I I I O I ON 1 o t 1 C3 o Q Q r-i ti O Q u o > C\J ON Z TH iri H 4) Q> CJN +^ •*-' C4 ON CM -rH f-i UN •-0 ^ U rn 0) O o t I I I H-* Ja x; (~i TH Ci o. O 25 UN bH ^ CO 00 1 o o o CO to X! JS ^ •H cx a. a. O 03 I o CQ CO 1 1 O 0) CQ +-' OJ +-» O-H O I UKKKIU:-. PHOSPHiiTEo Saleeite Metasaleeite Ms(U02)2 . P20e . bH20 3. Antunite ^s(U02)2 • PSOB ; 10'=.2C Mels-outunite I C&(U02)2 • P2O3 . 6E^0 ?. Meta-outunite II 3a(U02)2 • PsOa . 2E2O Bassetite Fe(U02)2 • ?20g . Ci) F-^ Torbernite G.i(U02)2 • P208 . 12 E^3 eta-Torbernite 'Ju(U02)2 • P208 • SK^O r'nosphurany lite (UO2) . P2O8 -6^^^ ?-2^ Parsonsite Pb2U02 . ^2% . K2O Dewindtite Pbg (U02)5 ^°^^^ ^^0^)^ lOKpO Uranocircile Ba(U0^)gCP0^)2 . 8K2C 5. Renardite Pb (U02)i^ (OH)j^ (POH)^ . 5 KJO Dumontite Pbg (UO^g (OK)l^ (P0i+)2 . 3h20 Zsselbornite (I'D, Ba) (UO2), (BiO)^^CASB)g) (OH) • . 3 H2O Tristranlte (Cair+) (.-^01+) . HpO Uranospathite :a (U02)2 ^^^^2 .2 E-O Upalite Al ( U02)3 ^ ^°^'^ ^'""O^^a ^ • 7 ^2° Fritzscheite Mu ( UO2 )2 (^Oi^ , VOi^) 2 • 8 HgO Un-named Uranium phosphates (Ccmt.3 504 Sl.Ko. NOMENCLATURE CHEMICi^L COMi^OSIIIOL II HERE - Ei^RTh - PEOSPHiiTES 21 Xenotime (y, ?0l+) , small amounts o:f Br, Ce, Si, Ih etc. dc iMonazite (Ge, POi,.), small amounts of La, Nd, ?r, Sr, Th, SI etc. 23. Rhabdophenite C La, Nd, ?r, Y, -Ir} POi^ , H^D) 2H (Hit ^a» ^^S (^e, Y)i^ 3i-?^2°56 . 13K2O ?) 25. 'Jhurehlte (Ga3Ge^Q (POi^)^. . SHK.O ) 26. W'einschenc.'Cite ( Sr,y) POi^ . 2K2O ) 27. Daqingshanlte Rare Earth Phosphates 28. Abukumallte (y, Ga, th)iQ (?Oit SiOi, AlO^) ^ (F, 0). 2Q. Brithollte C Ce, Ga, Na)^ (SiO^, PO^) ( F, OHO. 30. Fiorenclte Ge AI3 ( POlt)^ (CK)^ 31. Churchite ( Ge, Ga ) POt+ . 2 H2O ? 32, Kagatelite ( Ga, Ge)2 (Al, Fe)^ (SL=)^ 0^2 (0» 0^* CCc^t.) Ill ALUMINUl-1 - PrlQSPhklEo 505 33. Berllnite ( Ai, fCuJ . y'^. Variscite (Al, Fe) ?0i^ . 2H20 35. Ketavariscite Al PO- . 2 K2O 36. Veshegyite Al- (Gr:)g (?0i^)^ . 27 H2O ? 37. Lazulite (Mg, ?e) (Al 0K)2 . (POi+) 3b. "eruleolactit A1/(0K)^ CPOl+)i^ . 7 K^O 39. Minyulite S Al^COH,?) ?^0y . h H^O vo. Sterrittite Al (OH)^ ?^0^^ . 5 K2O hi. -Vavellit e Al£, (?, OH) (?Oi+)g . 9 K^O hk. Overite 2a HIQ (Or)^ (?0l+)3 . 15 R2O ^3. Souzalite (Mg, J'e)^ (Al, ?e)^ (Oh)^ (^Oi^)^ . 2 h20 ^h. P-oscherite J a (Ku, ?e) Al, OK .P2O3 . 2 ^20 ^5. /.ontgomeryite 3a^Alc (OK)^ (^^01+)^ . 11 H^O i+6. Metavauxite ?e,iil2(0K)2 ?2% • 3^12° ^7. Vauxite ?e, AI2 (OH)2 P20g • 5 H2O ^8. Parevauxite Fe, AI2 (0H)2 ?208 • 8 H2O ^9. Gordonit e Mg,Al2(0H)2 (P0i^)2 . « H2O 50. Planerlte Al6 (CH). (?Olt)i^ . 15 H2O 51. Griphlt e (Na,Al,C;a,Fe)^ Mni+(OH)^ (PO1+) 5^. FLoPencite (Al(OE)g) Ce?20t3 53. Augelit e Al (OE)^ POl^ 5^. Brezilianite Kaiil3 (On)L^ P2O8 ^5. iiUblygonite Li, Al (F,OH) ?0i^ 56. Fremont ite Ka, Al (Oh,F/ ?oi4. 57. rtardite Nai^ Ga Al3^2 (0^')l8 ^^^k'^Q • ^ "^2^ 58. Millislte Ka2Ca2Al^2 ^^^^8 ^^Oi+^g- ^ ^2° CCont.) 506 59. Dennisonite 6o. ?suedowaveIlite Ca Al3(0K) (i'<\)2 . K2O 61. Fischerite 62. Unildrenite Fe, ill (OH)^ POi^ . K„0 63. Englishite 6f. Mori nite 65. Lehiite Na2 Ca. iilg (OE)^. (?Oi+)g. SKgO 1^:i^q'aDise by. Kamlinite/Goyazite 6b. Govceixite H2 3a (Al (OH)2)^ '-^^^^^ 69. Flumbogummite H2pb (Al (CH).)^ ^'''^h\ 70. Tevistoclaite J 33 Al^ (CE)^ CPOi^)^ 7 H^O 71, Spherlt e ^Ho ^°"^lo^°l6 72. Crandailite ( J a iil^(OH)y (?0i+)2 • "2O •• ^ 73. Lacroixite Nai^ (Mn, Ca)i^ AI3 (?, OH)^ (PO^^) 74. Jazekite Nai^ Ga AI2 (OH)j^O (?0i^)2 75. Liroconite CU2 Al(OH)i^ (AS?) 0^. ifE20 76. Evansite (Al (0H)2)^ (P0i+)2 . li^ H2O 77- Kehoeite Ca 2n^ iiyOH)^^ (POlt)^ . 21 HgO IV IRpN - PKOSr^HAlES 78. Heterosite ( (Fe, Mn)i ?0i^ ) 79- Phosphosiderite Fe ?0i4. . 2 H2O hO. Koninckite (Fe, POi^ . I H2O) 81, Siclilerite ( Li, Kn POi+ . n Fe POl^.) 62. Craftonite ( (Fe, Mn, 09)3 (P0^)2 ) B3. FillovJite (Mn, Fe, 'Ja H N8)3 P2O3 8W. Stren.^ite Fe POi+ . 2 H2O LCo-rit.) 507 85. iirrojedite (Na, K, Ca)2 (-"e, l-'.n) ^ (.?0k)^ 86- Beddingite ?l'in,?e) (POi^.). . 3 K2O 87, • Salmonsit e ti8. Collinsite Ca2 (I^S, Fe) {?0L^)2 . 2 K2O b9. Fairfieldite Ga2 (^'n, Fe) (--=01^)2 • ^ H2O 90. Phosphophyllite Zn2 (Fe, Mn) (?0^)2 . "+ '^2^ 91. Vivianite Fe^ P20g . 8 K2O 92. Picite Fe^ (OH)^ (-^01+)^ . 7 H2O ? 93. Anapaite Gs2 Fe (?0i^)2 • ^ ^2° 9^- Alluaudite ( Nai^ (Mn, Fe)^^ (F, OH{>j^ (POt^) ^Q) 95.' Pharirecosiderite Fe (OH)^ (AS 0^)^ . 5 K2O ? 96, Landesite Mn^Q Fe^ (OH)5 (i^a^)g . 11 K2O ? 97. Berannite Fe^ (OR)^ {^(\)^ . 5 H2O 98. Galeioferrite 033 Fe2(0E) (POk)^ . B H2J) 99. Xenthcxenite ( Ga, Mn, Mg)2 Fe (?0i^) (Oh). 15^:^0 loo. Lithophilite Li (Fe,Kn) ?0^ 101. Varulite Na (Mn, Fe) PO;^ 102. Trip lite ( (Mn,Fe,Kg,C5)2 F ?0i^ ) 103. Triploidite ( (Mn,Fe)2 OH PO^^) lOH. Dufrenite (Fe,Fe^(OK)^ (?0i^)^ . 2 K2O 105. Ro ck: brldgeit e-Frond ell t e Fe, Fei^(OE)^ ^''%^2 ' ^'^^'^^^h^^^K^^^^^3 106. Gacoxenite Fe2(OH)2pOit . ^.5 K2O 107. Ludlarnit e Fe6 (POi^)^ . 8 H^O 106. Chalco-siderite Gu.Fe^ (OH)g (POi^)^ r ^ K2O 109. Delvanxite Fei+ (OH)g (?0i+)2 . 17 H2O 110. Azovstcite ( (Fe3 (OH)^ . ?0i+ ) 111. Boricrcite Ca^Fen^ ^°^^30 ^^^'*\ 112. ' Tlncticite Fe^ (OH) POi^ . 3.5 H2O (Corit) 508 113. Iron-Barringenite (^^2' ^^^ 124. wllhelmvierlin^ite (Ca, Zn) Mn, Fe^'*' (OH) 115« Ferostrunzite Iron-Hydro3cy apatite 116. Phosohofibrite . Iron-Hydrated phosphate 117. Wslentaite Iron-Jirsenate Phosphate V CALJIUI>1 , PHQSf^HATES 118. Apatite -a^CPOi^i (Fi, :i) 119. Fluor-apatite 3 033 P^Og . 3a F2 120. Chlor-apatite 3 Ca^ ?203 . Ca 'JI2 121. Hydroxyl-apatite 3 ^a^ P2^=y. --^ (^^)2 1^^. Podolite/Jarbo-apetite 3 Ja^ P Oo . ^s Jo-. 123. Stroritian-apatite 3 (oajSr;^ '^2'^b*^^ (F,Oh)^ 12^. Manganian-apatite 3 (CsjMn)^ ^2^8*"^ ^2 125. Britholite 3 (^3,^6)3 (Sip)^Og. Ja (0K)2 1^6. Abukunalite 3 ('-ajY)^ (Sl,?)208. -a (0H,?>^ 127. Dshllite Between hydrsxylapat ite anc^ oodoiite 1.^8. Francolite Beti-ieen fluorapatite and oodolite or an hydrous form of shaffelite 129. W'ilkeite Between hydroxyl-epat it e and ellestadite 130. }jedyphane Between mimetite and apatite 131. Fermorite Between hydroxyI-apet ite and svabit€ 132. Golloohane Carbonat e-hydrcxyI-fIuorlne-aa£tite (Ca3(P0l^) . 03003). 133. Monetite (H,Je POi^) 134. Brushite E, CaPOi^ . 2H2O 135. Herderite G8,Be (OH,F) PQ^ 136. Spodioslte Ca2 F POi+ 137. Isoclasite Ga20H ?0i^ . 2 E2O 131. Staffelite 3 Ca3(P0l+)2*-3F2. JaC03.B20 139.- Whitl.^clcite (L;a3 p^Og m YI ZIKC - PHOSPHAIES llfO. Eopeite ( 203 (POlt)^ . ^KgO) 1^1, Parahopeite 203 (P01t)2 . ^H^O 1W2. Tarbuttite Zn2 OH PGi^ 1^3. Spencerite Zni^ (OH)2 (P0it)2 * ^^2^ 11+1+. Veszelyite Zn, Gu (OE) (9Ae)0i^. 2H20 3 *- 1^5. Arakewaite Zn CugCOE) POi^ . 2K2O VII MAGSESIUli - PHOSPBAISS 11+6. Bobierrite (Mg3 PgOa . 8S2O 1^7. Newberyite (E, Mg POl^) . 3 H2O) 11+8. Phosphorisslerite (H, Mg POj^ . 7 H2Q> 1^+9. Wagnerite (Kg^ F POi^) 1$0. Lueneburgite Hg B2 06 . Mg3 PgOg . 5 H2O 151. Bradleyite (Mg CO3 . Na3 PO^) VIII KiiNaAl'IESE - PHOSPHATES 15^. Stewarite Mn3 (P0^)2 . ^ HgO 153. Bermanite Mn5 Mng (OH)^^ ^^^^^Q ' ^5 HgO 15'+. Seamanlte . Mn3 B20r Mn3 ^2^9 • 3 ^2° 155. Natrophilite Na, Mn POi,. 156. DicicinsoDite H2 Na^ MDJ^^, (POlt)^^ . HgO 157. Palaite H2 Mn^ (?01t)j^ . 3 H2O 158. Hureanlite H2 Mn^ (POi^)^ . ^ HgO 159. Purpurite (Mn, Fe) POi^ 160. Laueite Mn Peg POi^ (OH)^ . 8 E^O 161. Eithiophillte Li (Mn, Fe) POi^ 162. Manganapatite (Ga, Mn)j (?0^) (F, OH) 163. Reddingite (MnjFe)^ iP%)^ . 3 H2O iCo-rit.) m i:-. LSi.D - PhC'or^hiiTES It^. Pyrocorohite 3 ?b^ P20b . ?b CI2 1^5. Gorkite ib Fe3 (?0i^) (Spi^) (OH)^ A VANAD: IT'! - PEOSPEATES 166, 5incosite (Ca (^^0^)^ P^O^ . 5 H^O ?) XI AiuCr.L luE - PHOSPHATES 167. Katrophylite Na, Mn POi^ I6b. Beryllonite (Na, Be POi^) 169. Sa^oleite Ka, :a, GU5 01 (POi^)^. 5H^0 170. Merrillite Na2 Cao 0 . ^o^b 171. Qingneiite Na2 ^^a ^^^^2 ^g^ (Ai, Fe)2 (PO^^)^ 17^. Nefedovite Nac Ga^^ (^Ol^.)^ F 173. Sobolevite Na^i^ Ca^ Mn Ti^ P^ Si^ 034 Zll ^AvXU IUi< - PHOSPHATES 17^. Struvite (NK^., Mg POi^ . 6 H2O 175. Hanneyite Hi^ (KH^)2 WS3 (POi^)^. 8 H2O 1^6. Stercorite (LHi^, Ka KPO1+ . i+ h20) 177. Mundraciliaite il^\).^ . CB(h?0^) ^ . K^O 17 ts. isjahite Hydroxy1-Ammonium Phosphate XIII COt^PlilR - PhOSPHAlES 179- Libethenite (GU2 OH POi^.) IbO. Ehhite GU5 (POi^.). (OH)^ . H2O 181, Tagilite Cu^ OH POi^ . H2O iQd, PsnedoD6le::hite Gu^ (0^)h (^OK) (Co-nt.) 511 1C3. Cornetite • (JuOh):* ?0 Ib^. :isumebite Ju ?b (Oh). PQ. , 3h20 lo5. Dixjydrite ju^ (^0^),^ COli)^^ Ibc. iurquoite Ju iiig (?0i^) (OH) . JH 0 187. Jnaicosideriite CuFe^ (^0^). (OK). . ^fh^O XIV BSHYLiuIuri ^ ?H0S?HATD3 Itib. Herderite Be BO^ (OH) XV Lllhl^Jll > PhGSPHAiSS 189. Triphylite Li (Fe.Mn) POi^ 190. Lithiophilite Li (Mn, Fe) POi^. 191. iimblygonite Li Al ?Oi,.F 19k. Fremontite (^a, Li) H1 POi^ (Oh, F) 193. Sickierite i.i ^ (Mn, ?e) POi^ XVI Sr, PHODPHAIES 19^, Strontioapatite (Ja,or)u (?0i+) (F,OH) 195. Goyazite 3r i^-j (PO^.) (HPOi^)' (.OH), 196. Svanbergite Sr Al-j (POi^) (SQ^) ^OH)/ X7II Cr - PHOSPHAIES 197. Vanquelinite(Laxmanite) Pb2 Cu (Cr 0^) (?0i^) CCont) 512 TABLE . XIj REdALCULAaED RATIOS 0? MAJOR ELh;t>^b:N'i S OK HHop^HpRI^ BIJAWAR CROUP OF STUDY ARBA Sample iJo. Roc'< Umts OoO/i^2<^5 J^a2'^/P2^5 '^02/P205 ^nO/ra. 1. Shble-i^hosphorlte 1.35 0.091 0.0't7 9.3'+6 2. 0.095 0.083 92.10 3. 1.3^ ©.n't 0.123 33.90 0.71 0.061 0.052 ^9.05 5. Uhk 0.103 0.100 25.32 1.50 0.081 0.062 32.27 7. Secondary-Phosphorite 1.33 0.007 0.0'tl 215.00 b. 1.3a 0.005 0.050 205.87 9. 1.12 0.002 0.030 10. 1.11 0.006 0.019 109.56 11. 1.03 0.023 0.025 Ironstone-Phosphorite 1.27 0.009 0.0^^ 3^.67 13. 1.21+ 0.012 0.076 357.66 11+. 1.23 0.008 0.038 8lf.66 1$. 1.26 0.010 0.051 313.25 16. 1.27 0.009 0.036 22.50 17. 1.33 0.009 0.035 28.80 16. Quertz-Breccla-Phosphorlte 1.17 0.020 0,131 19.51 1°. IM 0.018 o.o'+3 32.86 20. 1.36 0.008 0.038 93.12 21. l.kH 0.018 0.071 o.oio 0.032 36.1+8 i.kb 0.011+ 32.50 0.011 0.0^9 56. b9 1.35 CCont.) 513 Satsple Rock t'2^^/^^2^1 lotai Iron/MgO K820/K^0 Nos. Units 1. Shsle-Phosphorites 2.k2 37.3'+ 2.00 'd.. II 2.5*+ 27.H-3 1.97 3. ?( 1.9G 13.36 1.4-6 ^Z u 1.33 66.80 1.26 5. II 1.7& 20.01 l.bp 6. II 1.50 1^.2^ ^ 7. Secondary Phospho rites 2.27 71.85 1.^7 8. II ^.37 3^.0^ 0.57 9. II 38.2if - 0.53 10. II 13.38 IM 1.71 11. II 5.35 - 1.67 l^. Ironstone.?hospho- rltes ^.V2 ii.»+i 1.1^ 13. It 1.71 173.88 O.'fl 14. ti 1.66 hl.bh 0.29 15. II 2.97 86.75 - 16. 11 3.07 6.03 0.52 u 17. 2.if7 9.008 oM 18. Quertz-Breccis- i'hosphorltes 1.09 15.3^ 0.27 19. H 2.83 8.38 0lit2 20. M 3.27 21.25 0.18 21. ll 3.86 7.96 0.39 22. n 2.73 9.25 0.12 23. a 1.77 12.96 0.10 2»t. n 3.0if lif.13 0.12 TABLE: XII RECALCULATED RATIOS OF MAJOR AND TRACE ELffllEMS OF PHOSPKORFIES OF BIJAV^/AR CEOUr' OF STUDY AREA 1 Samole Rock M^O^/b^e^C U V/P 0^ CiV?-0_ Cr/Al20^ 3 2 :? I-.os. Units Va^'aS 1. Shale Phos 0.00^+5 0.009{i 7.3638 ^.5315 •• phorites 2. II 0.00^1 0.0106 5.6287 1.^770 i+2.1568 3. II 0.0015 0.0030 6.709? - 5.0000 h. 1) 0.0002 0.0003 10.1^7^ ^.0117 11.5655 II 0.0003 0.0005 5.^^^5 1.0556 B.309^ 6. n 0.0003 0.0005 8.92V9 - 3.8961 7. Secondary- Phosphorites 0.0025 0.0058 • 9.1900 19'+.'^051 8. u 0.0028 0.0123 - - 65.6321 9. tl 0.0032 0.1^32 0.0933 - - 10. II 0.0032 0.0'+31 •• m6H0 5.5636 11. II 0.0028 0.0150 0.6375 0.3825 - 12. Ironstone- Phosphorites 0.0022 0.0055 •• 6.1863 25.7627 13. II 0.0018 0.0032 0.5771 7.387^ 117.829»f Ik. II 0.0019 0.0031 l.Obi+9 - 285.71^2 15. n 0.0023 0.0069 2.525^ 6.0606 - 16. n 0.0021 0.0065 - 5.61^ 152.5000 17. A 0.0019 0.00^8 3.7^62 5.3783 218.9873 18. Quartz-Brecci a- Phosphorites 0.0002 0.0002 - 12.0757 33.9256 II 19. 0.0029 0.0082 1,7299 6.^978 - II 20. 0.0026 0.0087 - ^.2168 102.3690 tl 21. 0.0036 O.Ol'+O - 10.7773 215. •'+^71 j) 22. 0.0027 0.0076 5.7597 - 36.1111 23. II 0.0022 0.0039 0.50^+2 8.1232 58.5365 2k: tl 0.0035 0.0168 1.7550 5.1919 . TABLE XIII; RS:iiLCULi..TED WEIGKT PER: iLEMSKTS OF PHOSPHORITES OF BIJAWAR CROC? OF ' ^^ STUDY iiREA SJL. Rock Units Si02 Total No. CsO + MgO ft /- 1. Shele-Phosphorites 29.35 'to. 15 30.'+8 2. II 22.66 ^5.76 31.57 3. H 22.1+8 1^5.68 31.82 k. It hh.e5 32.'+!+ 22.90 5. II 40.90 35.51 23.57 6. II 50.85 29.88 19.25 ?. Seco nd ary-Piiosphor it es 5.39 5H.27 '+0.33 8. 1) 3.18 56.27 '+0.53 9. ii 2.16 51.79 ^c.G^t 10. II 3.^2 51.12 '+5.'+'+ 11. n 3.^2 51.12 '+5.'+'+ 12. Ironstone-Phosphorites 2if.69 ^+2.71 3^.58 13. II 28.30 39.71 31.97 ih. II 27,05 'to. 50 32.^+1 15. n 21.05 kk.ie 3'+.78 16. II 2^.27 ^+3.07 32.6if 17. n 2»t.23 ^+3.95 31.81 18. Quartz-Breccia- Phosphorites 5^.72 2it.99 20.28 19. ti 33.90 39.0»+ 27.05 20. n 26.7** 1+2.50 30.75 21. n 20.81 '+7.26 31.92 22. • »i6.6a 32.20 '21.16 23. n »f2.86 3^.29 22.81+ 2h. A 22.85 '+'+.67 32.1+7 TABLE XIV; RECALCULATED '.>^IGLT PSHCBKTAGKS (lOO,t) OF MAJOR SL EIEKT'S OF PHOSPHORITES OF B.•JAWA R GROUP 516 OF STUEK AR-A SI. Rock Ti02 KgO P2O5 Ti02 MnO P2O5 I. OS Units •r It -* 1/ 1/ ^ f' /* /!• A /»" /• 1. Shsle-Phos- 1.8i+ »+.29 93.86 1.91 0.51 97.57 phorites 2. It 0.07 ^.60 95.31 0.07 0.55 99.36 A 9^.51 3. 3.67 6.89 89.1+3 3.88 1.59 k. n 2.25 ^+.56 93.18 2.33 1.13 96.52. 5. II Tr 5.31 9^.68 Tr 0.16 ^9.83 6. a ^.27 Tr 95.7^ 1+.21 1.21 9^.56 -I Secondary- 3.00 0.51 96.1+8 3.02 Tr 96.97 Phosohori- tes 8. It Tr 0.91 99.08 Tr Tr 100.00 9. it 0.0^ 0.30 99.65 O.O^f 0.02 99.93 10. ft Tr 0.3^ 99.65 Tr 0.96 90.0^ 11. il 0.10 1.33 9tt.56 0.10 Tr 99.89 12. Ironstone- 0.10 0.75 99.13 0.10 0.07 99.81 Phosphori tes 13. " 0.92 2.7**- 96.33 0.9^ 0.^9 98.55 l^t. a Tr 2.58 97.^1 Tr Tr 100.00 15. n 0.13 Tr 99.86 0.13 0.36 99.^9 16. il 1.69 1.62 96.67 1.71 0.3^ 97.93 17. n 1.78 1.85 96.35 1.81 0.36 97.82 18. Quarta-Breccia Phosphori 2.77 6.63 90.81 2.70 0.81 96.it7 tes 19. II Tr ^+.08 95.91 Tr Tr 100.00 20. 11 l.i+2 3.95 9^.62 l.'+7 0.33 98.18 21. n Tr ^M 95.5*+ Tr Tr 100.00 22. a 2.02 1.11 89.75 2.65 0.53 96.81 23. n 3.65 12.62 Bit.71 If. 13 Tr 95.86 2\. a 0.63 7.98 91.37 0.68 0.^3 98i87 TABLE XV; HEJ.t,LJTJLA:£D ••j-ilGhT .-'ERCfclM'AGKS (IQO/) OF JMAJOR 2L£iMEI;lS OF PHOSPHOR TIES OF BIJA.;^R GROUP OF STUDY AREA 517 Hock SIO2 AI2O3 1^20 SiO^ No, •Units (t=totel) 1. Shale-Phos phorites IbM 29.32 5^.23 22.1+1+ 3.51 71+.03 2. II 15.09 31.67 53.22 20.99 If.98 7H.02 3. fi 1^.69 37.33 ^7.97 21.61+ 7.70 70.61+ h. n 13.25 21+.97 61.77 17.30 2.02 bo. 66 5. fl l^.3c 21.26 6^.35 17.79 2.57 70.62 6. i( 16.99 16.68 66.32 20.39 Tr 79.60 7. Secondary- Phosphorites 7.6^ 71.13 21.23 25.67 2.tS4 71.50 6. II 13.67 61+. 22 22.09 35.65 6.76 57.56 9. II 62.53 13.75 2i+.69 70.1+0 1.79 27.60 10. n 52.90 23.5^ 22,.5h 66.23 1.39 30.36 11. fl 39.^+^+ kl.39 12.97 70.71^ 6.00 23.21+ 12. Ironstone- Phosphorites 8.35 32.65 58.99 12.29 0.87 86.82 13. II 3.22 39.17 57.5^ 5.15 2.95 91.89 ft lit. 2.1+7 1+1.20 56.32 1+.O8 2.95 92.95 15. n kM 35.03 60.51 6. 83 Tr 93.16 16. n 6.09 29.38 61+. 52 8.lfi+ 2.02 6;.52 17. A 9.03 32.20 58.75 I3.0I+ 2.1i+ bi+.8o 18. Quartz-Brecc la- Phosphorites lO.Oif 22.91 67.01+ 12.72 2.30 61+.96 19. II 5.93 20.87 73.18 7.27 3.0I+ 69.67 20. n 8.53 21+. 15 67.30 10.79 1+.O6 65.11 •1 21. ^.55 27.13 68.30 5.85 6.28 87.85 II 22. 10.30 13.07 76.62 11.1+5 3.35 65.19 23. n 13.70 20.39 65.89 16.23 5.70 76.05 2k. n ^+.65 30.80 61+. 53 6.03 10.37 83.58 IHBLE XVIS RKCiiLCULAahD WEIGri FtJRJiili'.lAati.S (lQO.g) 01?'' MAJOR ELa-EI^lS OF j^HOS^HORIi b^S OF SIJAriiiR GROUP q | g OF STUDY hREA Sample Rock Types GaO ^^2^3 Fe203 ;. Shale Phosphorites 63.73 1^.27 21.99 2. II 70.61 10.02 19.31^ 3. n 65.92 13.23 23.8^ H. ft 5^.59 16.25 29.1^ 7. n So.'tH 16.17 23.38 6. II 52.88 23.77 23.3^ Secondary-Phospho rites 73.35 2.62 2if.0l 8. II 83.29 2.93 13.77 9. 88.5b 9.36 2.05 10. 1) 82.03 i^.^7 5.^9 11. ii 7^.87 11.55 13.56 12. Ironstone- Phosphorite 71.0^ 5.98 22.96 13. II 66.16 2.65 31.18 I'*. n 66.02 1.95 32.01 15. A 76.85 2.69 20.'+lf 16. n 76.15 ^+.23 19.61 17. n 71.9*+ 6.31 21.7^ 18. Quartz-Breccia- "+7.05 16.22 36.72 Phosphorites 11 19. 75.56 5.^8 19. ^+2 20. i) 76.70 6.18 17.10 21. n 82.73 2.i+8 li+.77 22. n 69.12 13.62 17.05 23. n 60.39 16.19 1 23.^1 2^. n 78.09 2.93 18.96 519 Plate-1, t Shale-Phosphorites i Photomicrograph-A : The collophane pellets are angular to sub-angular in shape and show initial stage of weathering (whitish). Collophane grains are occasionally very fine to medium grained (crypto- to micro- crystalline sizes) and embedded in a groundmass of ferruginous minerals tblack colour) alongwith other gangue minerals like fine grained quartz# chlorite, sericite and clay minerals. The criss cross fracture fillings by ferruginous, siliceous and phosphatic solutions are ubiquitous* Occasionally/ there are few euhedral hexagons of apatitic (collophane) which are embedded and surrounded by larger grains of collophane pellets. The crypto- to micro- crystalline collophane granules sometimes make pseudo-rings and aggregations. Plate-I » shale-Phosphorites : Photomicrograph-B : In this photomicrograph, the cellophanes appear very fine to coarse grained. They are angular to subangular and lath shaped (whitish). The fine grained collophane grains show micro-laminationi and ring like structures. The cellophanes which are amorphous, show interstitial textures in a groundmass of ferruginous materials (black) and. were associated with gangue minerals like fine grained quarts: (whitish), clay minerals (black), etc. The dark coloured iron-oxides are pervasive in thin sections. PLATE-1 ^20 PHOTOMICROGRAPH - A PHOTOMICROGRAPH - B 521 Plateau I Socondftry PhoaphoritCB i Photomlcrogrfiph-C t This photomicrograph shows the recrystalllzation of phosphate minerals to form crandallite (aluminous phosphate). The crandallites (white) appear crypto- to microcrystalline; elongated and lath shaped; and angular to subangular and sub- rounded in shape• The mineral showing intergrowths towards the Cavities/voids which are filled by ferruginous (black) and phosphatic materials that appear as a cementing material. Occasionally* the pseudo-microlaminations and ring like struc tures are still preserved after weathering and leaching of primary shale phosphorites. The ferruginous minerals may be hematite, magnetite, goethite, limonite and iron-oxides associated with fine grained clay and quartz forming gangue minerals. Sometimes, the crandallite also occurs in massive, ovulitic to oolitic and disseminated forms. Twinned crystals of crandallite also seen in this photomicrographs. PIate-II i Secondary Phosphorites s Photomicrograph-D : At the centre of this photomicrograph, the filling materials appear to be one cavity filled by ferruginous, siliceous and phosphatic. The secondary phosphate mineral like crandallite (white) shows a progressive growth towards the border of cavity. The mineral occurs in the form of crypto- to microcrystalline, granular, amorphous, lath, disseminations and subangular to subrounded grains. The fine grained amorphous pellets occur as primary laminations. The gangue minerals being very fine grained, are quartz, ferruginous and clay minerals and which are mostly confined to the groundmass in which the crandallite grains are embedded. The ring like structure of the fi ne to medium grained pellets is displayed in the photomicrograph. These all above features of the rock supported remobilization and repreci- pitation of the phosphatic and its associated minerals. PLATE-II ^•ZZ PHOTOMICROGRAPH - C PHOTOMICROGRAPH - D 5Z3 Plate-Ill : Ironstone Phosphorites t Photomicrograph-E s In the photomicrograph of ironstone or highly ferruginous shaly-phosphorites, collophane which is crypto- to microcrystallin^ appear concretionary. These fine grained collophane (white) pellet show discontinuous, thin, microlaminations. The mineral is granula- massive, amorphous, spicular, ovulitic to oolitic in shape. Fine grained spicules of collophane are making ring like structures. Quartz is also very fine grained. The dark coloured ferruginous anc clay groundmass is pervasive in which collophane is embedded. Th^ dark-coloured fracture fillings also clearly seen in the middle as well as at the bottom of the photomicrograph. Plate-III a Ironstone Phosphorites i Photomicrograph-F In this photomicrograph the collophane pellets appears micro to macrocrystalline. These fine grained collophane makes discontinuous ring like structures. The bigger pellets of collophane are elongated, twinned, lath shaped, angular to subangular and subrounded in shape. The collophane pellets are amorphous, spicular, colloform and hexagonal in shape. Few bigger pellets show intergrowth and/recrystallization. These light coloured cellophanes are embedded in the fine grained groundmass of quartz (white), clay and black coloured iron bearing minerals. PLATE-in SZ4 PHOTOMICROGRAPH - E PHOTOMICROGRAPH - F J tw tj Plate-IV : Ironstone Phosphorites ; Photomlcrograph-G : In this photomicrograph, the collophanes (white) are mostly crypto- to mlcrocrystalllne In nature which are embedded in the huge groundmass of black iron bearing minerals• The collophanes are granular, amorphous, spicular, ovulltic, disseminated and weak thin microlaminations in shape. At places, the fine grained spicules of collophanes are making pseudo-ring like structures. The very fine grained quartz (white) grains and clay minerals are also seen as gangue minerals. Plate^IV ; Ironstone Phosphorites ; Photomicrograph-H : In this photomicrograph, the cellophane is medium to coarse grained though some fine grained spicules of cellophane are rarely present. At the centre, needle shaped (white) recrys- tallized collophane and/crandallite is also seen. The collophanes are pelletal# lath shaped and disseminated. These light coloured collophane is embedded in a dark ferruginous and clayey groundmass PLATE- iv c' k^ U PHOTOMICROGRAPH - G PHOTOMICROGRAPH - H ^2.^ Plate-V : Quartz-Brecclated Phosphorites ; Photomicrograph-I : The photomicrograph of this type of phosphorite subrounded (white) of guartzlte and angular fragments of older schistose rock (whitish). The darker and dirty whitish coloured materials cemented the brecciated and conglomeratic fragments of quartzites. The ground- mass is ferruginous, phosphatic or siliceous• The collophanes are crypto- to microcrystalline, macrocrystalline angular to subangular, massive, fragmented, pelietal# spicules, lath-shaped, granular, etc. The dark coloured and subrounded to rounded shaped hematitic and magnetite grains occupy the inter-spaces of the brecciated fragments-^ of the quartzites and schistose rocks. These dark coloured magnetite grains are fine to coarse grained. The phosphatic minerals are embedded in the fragmented brecciated rock masses, clay and ferrugi nous contents. Plate-V ; Quartz-Brecciated Phosphorites : Photomicrograph-J : In this photomicrograph, the broken angular fragments of quartzites, schistose rocks (whitish) are clearly pervasive. The cellophane (white) are crypto- to microcrystalline, mega-crystalline^ angular, amorphous, pelletal, spicular, ovulitic to oolitic, nodular pseudo-oolitic, fragmental# etc. The fine spicules of collophanes made very thin discontinuous ring like structures. Some collophane pellets are lath-shaped with thin veinlets of crandallite and show growth towards the interspaces of brecciated rock. Few dark coloured and subrounded to rounded magnetite grains are also among the rock fragments. The dark coloured ferruginous and clay minerals compose the groundmass in which some phosphate minerals are embedded. No laminations were seen in this typte of ore. PLATE-V m PHOTOMICROGRAPH - I