PETROiOGY AND GEOCHEMfSTRy OF AHAR RIVER GRANITE* NORTH WEST OF UOAfPUR. RAMSTHAN
DISSERTATION SUBMITTED FOR THE DEGREE OF jfMagter of ^Iiilosioplip IN GEOLOGY
BY ABDUL RAHMAN
DEPARTMENT OF GEOLOGY ALIGARH MUSLIM UNIVERSITY ALIGARH (INDIA) 1987 Sed in I. oirtD atai
2 SEP 1988
DS1171 -> '^ ^^' c?^ DEPARTMENT OF GEOLOGY ALIGARH MUSLIM UNIVERSITY
Dr. Syed M. Zainuddin M.Sc, Ph.D.(U.S.A.;, Dated: November 17, 1987 Sigma XKU.S.A.;, F .G .S . (India J
This is to certify that Mr. Abdul Rahman has completed
his research work, presented in this thesis, under my
supervision for the degree of Master of Philosophy of the
Aligarh Muslim University, Aligarh. This work is original
and has not been submitted for any degree at this or any
other University.
( SYED M. ZAINUDDIN ) In the name of Allah, the Beneficent, Most Merciful
The author wishes to express his deep sense of gratitude to his supervisor and guide Dr. S .M. Zainuddin, Reader,
Department of Geology, Aligarh Muslim University, Aligarh for his keen interest and valuable guidance which led to the completion of this research work. His thanks are also due to Professor S.M. Casshyap, Chairman, Department of Geology,
Aligarh Muslim University, Aligarh for providing laboratory and library facilities.
The author is extremely grateful to Dr. V.K, Srivastava,
Professor, Department of Geology, Aligarh Muslim University,
Aligarh for his keen interest, help and encouragement during the course of the work. The author is also indebted to
Dr. Shahid Farooq for his kind help in chemical analysis.
Thanks are also due to Mr. Shamim Ahmad Khan, authors one time colleague, for his kind cooperation. Help and encouragement from authors friends and hostel roommates are also gratefully acknowledged. The author wishes to thank Mr. Zakir Husain, Librarian,
for his help in the course of study, Mr. Firoz Javed for chemical analysis and Mr. Wasim Ahmad for typing of the manuscript.
ABDUL RAHMAN CONTENTS
Page
LIST OF TABLE I
LIST OF FIGURES II
INTRODUCTION 1
Geography of the Area 2
Previous Work 3
GEOLOGICAL SET-UP 6
PETROLOGY OF THE GRANITE 13 Modal Composition 13 Petrography 16
GEOCHEMISTRY OF THE GRANITE 30
Geochemical Analysis 31
Major Elements 32
Classification of Granite 43
Trace Elements 47
SUMMARY AND CONCLUSION 60
LIST OF REFERENCES 6 3 Table No. Page
1 Stratigraphic succession of the 6 Precambrian formation of Rajasthan (Heron, 19 53).
2 Precambrian lithostratigraphy and n tectono-magmatic sequence of the Aravalli Super Group rocks (Anon,1981K
3 Modal composition of the Ahar River 14 Granite.
4 Chemical Analysis of the Ahar River 33 granite. II
Fig. No. £^22
1 Geological map of Ahar River granite 8 northwest of Udaipur city, Rajasthan.
2 Irregular fractures in K-feldspar filled lo by thin veins of silicic material.
3 Ternary diagram of quartz-Plagioclase- 15 K-feldspar modal values for Ahar River granite.
4 Modal values for quartz-Plagioclase- 17 K-feldspar superimposed on Streckeisen's classification .
5 Fresh and unaltered polygonal quartz is grains.
5 Inclusions of quartz in microcline. 20
7 Quartz veins in microcline. 20
8 Recrystallized quartz grains. 21
9 Elongated quartz grains parallel to 21 foliation.
10(a,bJ Plagioclase grains showing bending, 23 fracturing and dislocation of twin lamellae. Ill
Fig. No. Page
11 Bands of sericite filled in feldspar 25
fractures.
12 Bands of sericite and muscovite enveloping 2 5
the feldspar crystals.
13 Aggregates of quartz grains surrounded 27
by sericite.
14 Plagioclase grain showing combination of 21 albite and pericline twins.
15 Inclusions of apatite in biotite. 28
16 Plots of total alkalis vs. SiO„. 37
17 Variation diagram of major element oxides 33
as a function of the Si02 content of the
Ahar River granite.
18 Plots of major element oxides against 40
Solidification index (S.I.J.
19 Plot of Na20 and K^O contents of Ahar 41
River granite.
20 K^O - Na20 - CaO plot for Ahar River granite.42
21 Plots of Ahar River granite on K^o; Na^O 46 diagram of Hine et al (1978).
22 Plots of Al^O^/^'Z&O-^l^a^O^Y.^O) (molecular 48 proportions) against SiO , after Sandra et al (1986). IV
23 Ternary diagram showing the Ahar River 49
granite composition plotted in terms
of Al-Na-K, Ca and Fe+Mg after Hine
et al (1978;.
24 Variation diagram of Sr, Rb and Ba as 51
a function of the SiO^ content.
25 Variation diagram of Sr and Rb vs K 0. 53
26 Variation diagram of Zn, Cr and Ni as 56
a function of the SiO^ content.
27 Differentiation trends of the Ahar River 58
granite, after El-Bouseilly and
El-Sokkary (197 5;. CHAPTER - I
INTRODUCTION
The Ahar River granite, exposed towards northwest of
Udaipur city (Rajasthan^, covers an area of about 24 sq, kiris.
The area lies between latitudes, 24°36'38" and 24*^47' 30" and longitudes^ 73 36' and 73°42*. The shape of the outcrop is triangular. The granite occurs within low grade Aravalli phyllites, bordered by the bands of quartzite and limestone on its western and eastern margins respectively.
Heron (1953J conducted the first comprehensive study of the area,* he considered the Ahar River granite as intrusive into the Aravalli rocks of early Proterozoic age. The granite is a fine grained type (aplogranite^ and forms bosses with very irregular margins and satellite intrusions showing all the features of intrusive granite (Heron, 1953 J.
Crawford (1970^ determined the radiometric age of the
Ahar River granite and concluded that it as intrusive into the Aravallis. However, Roy et al (1985^, on the basis of its stratigraphic position in relation to metasediments and 2
metavolcanics, inferred that the granite constitutes the basement of the Aravallis. The relationship of the Ahar
River granite with the Aravallis has been controversial.
The proposed study was made to resolve this problem and also to ascertain the origin of the granite.
Geography of the_Area
The Ahar River granite is exposed towards the northwest of Udaipur city in Rajasthan, The area is easily accessible by road,* a metalled road from Udaipur city to Bari Lake passes through the area. Bus services are very frequent from Udaipur city upto Bari Lake. Few cart tracks and pack tracks also join the metalled road from nearby villages.
It is almost a plain area which has a maximum elevation of 4000 feet above sea level. The Ahar River runs through the northeastern side of the granite body. The river is generally dry during cold and dry months of the year. The climate is semi-arid and the rainfall is low. Vegetation is generally poor and is controlled by the proximity of ground water level. Cactus, bushes and spear grasses are common. 3
Gardening and agriculture is done in low lying areas,' the source of irrigation is mainly the ground water. A low lying narrow band in the southwestern margin is densly forested.
Previous work
The Precambrian region of Rajasthan was first studied by Hacket (1877i who surveyed a large area of this terrain and determined the stratigraphic order of the rocks of
Aravalli range. He proposed a two-fold classification of the Precambrian rocks of the area, Delhi Series and the
Aravalli Series. However, his rock formation grouping has not been much accepted. Heron (1935J recognised three major granitic intrusions in the region, Bundelkhand granite
(Pre Aravalli^, aplogranite (post Aravalli but pre Delhi J and Erinpura granite (Post DelhiK Heron reported that this
aplogranite body is the most instructive intrusion in the
Aravalli rocks . The north and northeastern border of the
granite is fringed by limestone and phyllites. He reported the presence of lenticular sheets. Wisps and Knots of aplo- granites in the limestone, and abundance of limestone wedge. 4
xenolith and roof pendants in the granite, also granitic intrusion of all sizes in the limestone. He concluded that the aplogranite had intiruded into limestone. Evidence of contact metamoirphism at the limestone contact is not observed. However, silicification of limestone at the contact is common.
Gangopadhyay (1961^ has reported the granite as massive and homogeneous in composition and texture. The rocks is sheared,* twinning in plagioclase is often deformed and bending, fracturing, faulting and intricate folding are present.
Quartz is crushed and shows highly undulatory extinction.
He has observed that the twin composition plains in feldspar grains are parallel to the conjugate shear plane. It is inferred that the twinning in plagioclase is the result of intragranular gliding along shear planes due to flattening normal to foliation which resulted in the grain elongation along the plane of schistosity.
Crawford (1970^ used the term Ahar River granite for aplogranite, and determined the age 227 5 m.y. by Rb-Sr methods. Chaudhry et al (1984} analysed a series of Ahar 5
River granite samples but they did not yield acceptable isochrones. Anon (1981) grouped Udaipur, Salamber, Udaisagar and Darwal granites as Synorogenic granites and gneisses.
The Ahar River granite has been correlated with pre-Aravalli basement rocks by Roy et al (1985Ji.
A detailed lithological and stiructural study of the area has been carried out by many workers. However, detailed petrological and geochemical study to understand the petro- genesis of the granite has not been undertaken by earlier workers in the area. The aim of the present study is to decipher and delineate different types of granite in the area and to determine the orogin and the mode of emplacement of granite. Further, the relation of the granite with the
Aravalli metasediments was studied. 6
CHAPTER - II
GEOLOGICAL_S£T;UP
The Aravalli region in southern Rajasthan and north eastern Guj arat, covering an area of about one hundred thousand sq. kms., forms the western part of the Bundelkhand craton. The Aravallis provides a classic example of the
Precambrian supra-crustal evolution. Heron (1953J studied systematically the stratigraphic framework of the area and proposed a four fold classification of the Precambrian rocks of Rajasthan. Some modifications have been suggested later, however, his synthesis remains the basic framework of all subsequent work. The classification, proposed by Heron, is as follows ',
Table -1. Stratigraphic succession of the Precambrian formation of Rajasthan (Heron, 19 53 J
Vindhayn system Malani volcanics Erinpura granites Delhi system Railio series Aplo granite Aravalli system Banded Gneissic complex and Bundelkhand gneisses 7
Heron (1953 J deciphered three major granitic intrusions in this terrain. They are Bundelkhand granite, aplogranite
(around Udaipurj and Erinpura granite, of pre-Aravalli, post-Aravalli but pre-Delhi and post-Delhi ages respectively.
The aplogranite is exposed in the northwestern and south eastern side of Udaipur city. The granite, intruded into
Aravalli rocks, is a fine grained type forming bosses with very irregular margins and satellites intrusions. The granite exhibits all the features of the intrusive type.
Crawford (1970J used the term Ahar River granite for aplogranite.
The area under present investigation lies towards the northwest of Udaipur city (Fig. 1). The triangular - shaped granite body is flanked by Aravalli limestone in the north and eastern side and quartzite towards the south and west.
Phyllite, exposed towards the eastern side, grades into biotite schist near the contact of the granite. Heron (19 53/ considered the fine grained biotite schist to be relatively deep seated and a more metamorphosed representative of the
Aravalli phyllites. Coarsening of phyllite to form biotite schist as a consequence of recrystallization may be attributed 8
71 i.0
N
I I i
/-l—1-. .-Lj.j. t±r,iz] x'^x ^ J—.—1—j~ J—J ^•l—^T—1~^—i X X » XX V X -7 XTX^T *XXX '* "X X*X XX X
X XX X , If*' „x $f} X xx^i'^X ,5^^ x-^•xj<^ X xx^^JxtlilEtj( X x^^ ! #"• Xx X X X -\. XX --^^-~A%h. X
:^
3 LOCATION MAP —I..
J— \W^x\ AHAR Rr, ER GRANITE iz Q'JAR i ZITi'
PHVLLITC Mis. 1000 500 i"HH LtMESTC IE 2-^ KMS 73,40 3^"
FIG; 1 GEOLOGICAL MAP OF THE AHAR RIVER GRANITE NORTH WEST OF UDAiPUR CITY, RAJASTHAN . 9
to the contact effect of the granite. The relationship of granite and limestone is very complex/ the contact is intricate because of numerous veins and apophyses of the
Ahar River granite enclosing and cutting across blocks of limestone. In the central part of the outcrop towards the western margin at the contact with metasediments, the granite is coarser and aquires a porphyritic texture having pink phenocrysts of feldspar. There is however, a complete gradation from fine grained granite to the coarser pink and porphyritic variety (Heron, 1953).
Occurrence of limestone and banded quartzite as xenoiiths and roof pendants within the granite is common (Heron, 1953 J.
The central portion of the pluton comprises of normal granite which grades into the fine grained aplitic rock towards the limestone contact. Veins and sheets of this aplitic material traverse the Aravalli biotite schists and limestone towards its periphery. The field relationship of granite and limestone provides evidence of intrusion. The outcrop of limestone has general appearance of being set into the granite with their stratification dipping at high angles to the north or northwest as if the granite had cut its way upwards along iO
bedding planes without collapse or rotation of the blocks of limestone which had remained in position (Heron, 1953J.
The geology of the area has been reviewed by later workers. On the basis of tectonic setting, lithostratigraphy, deformational history, magmatism, metamorphism and radio active dating, the Aravalli Craton has been assigned to three geological cycles, Bhilwara (> 2500 M.Y.), Aravalli (2500-
2000 M.Y.), and Delhi (2000-7 40 ? M.Y.;. Anon (1981) summurised the new data and stratigraphic classification of the region. In recent G.S.I, classification, the Ahar River granite, Salumber, Udaisagar and Darwal granites have been grouped as synorogenic granite, their age was dete.irmined as
227 5 M.Y. Table {2) shows the general lithostratigraphy and tectonic sequence of the rocks in the area.
Roy and Paliwal (1981^ suggested that the Ahar River granite is older than Aravallis. Roy et al (1985J have deciphered the structural and stratigraphic relation of Ahar
River granite with early Proterozoic rocks. On the basis of correlation of metasediments (which envelopes the south western side of the Ahar River granite^ with other regional u
-2. trecanibrian lithostratigraphy and tectonc-rr.agmatic sequtince of the Arrival 1 o-jp*^ in southern Hajasthan cind northeastern Gujarat (aftei Anon, 1981 ,'.
K.jaadn Form
6YNwRo.jt.NIC GiiMilTt. AND Cht.I6S CUDAIPUK,' bALUKEAR/ UDAISAGAR," DA.RWALl 22^
RAKHAB DCV ULTRAKAFIC SUITE
JHAKOL GROUP DCVDiA GROUP
Sarrdajee Formation {J.,J Devthari Formation (DV ) Rama Formation (N, ) vjoran Fonnation CJ,J Dapti Foi-mation (DV } Koilmal Formation (t-l, }
Khfiirii.or Foimation ( B, J
M jj :D « ^ o .'aria Formation IB ) jajjanqarh Formation (B, j (Kr^.'
Ban. wara mixed gneisses (U J I Zawar Fonn . (U_ I •' tvimach Formation {U^) ] Barai Magra Forir. I Formation D Balicha Formation (U,J I m '"6' X I V. I Mor-T ina 1 rj ] M-indli tkiingarh Formation (U^i Form,: i (m (K*-^; a, li, I Form/>tlr)n UK) oabina Foini iLion (U )
•- :3 I f. I I
ueoeri Sector Jaisarnand_Sector Ghatgl_3ector -iiJ_ki_i
^-•iTi-ir Kotra flabarmal Formation Jagpura Fonriation ( 1.-: ia Fr I •^, -. r ! ^;i-, Fonnation ^0^Q> Dakan Kotra Kuk andpura Berwas Form. (U^; Form Eition Formation (D^^J '.an' ' .^r a JaisaiTiand Jaisamand Formation Jai samand Fo rrr -•' L on formation (D, .1 Formation [D^) Deiwara Formation(D. th-:i i ,, V Uelwara Delwara rmnt i -jr. Formation (D„; Formation (D,J Gurali Quartzite (D^;
UNUlFftRbl^TIATbD URAMITtlS AND BAolC ROCKS 12
lithologies, they have concluded that the Ahar River granite is not intrusive into the Aravallis,* instead it constitute the pre-Aravalli basement rock. 13
CHAPTER - III
PETROLOGY OF THE GRANITE
The Ahar River granite is a light green, fine grained rock comprising of white feldspar at the southeastern side which gradually changes to coarser grained type with pink coloured feldspar towards northwestern side. The general texture of the rock is hypidiomorphic granular. However, some rocks are porphyritic,* large feldspar crystals are enveloped by fine grains of quartz and feldspars. The rock shows variation in the grain size. The major mineral composition, however, is nearly the same throughout the rock body. The granite is sheared,* irregular fracture filled by thin veins of silicic materials are common
(Fig. 2), Petrographic study was carried out to decipher the possible mode of origin and also to differentiate the various types of granite in the area.
Modal Composition
The point count method of Chayes (19 55 J was employed to 14
determine the modal composition of the rock. The thin sections were stained by the method suggested by Ruperts et al (196 4^ to differentiate K-feldspar from untwinned plagioclase. Uncovered thin sections were etched for 15 seconds in HF, vapour, then immersed into the saturated solution of sodium cobaltinitrite for 15 seconds. The
K-feldspars were stained bright yellow whereas, plagioclase remained colourless. After staining the slide, modal composition was determined. It was found that 1000 points and above give optimum accuracy. An average of 1150 points were counted. The range and average mode of granite composition is presented in Table (3) •
Table -3. Modal composition of the Ahar River granite ( 11 samples )
Mineral Mean Range
Quartz 33.03 46.23 - 19.84 K-feldspar 29.18 44.40 - 13.96 Plagioclase 26.76 44.98 - 8.55 Muscovite 6.94 13.27 - 0.61 Biotite 4.45 7.20 - 1.70 Chlorite 0.30 0.60 - 0.00 Sphene 0.45 0.60 - 0.30 Zircon 0.10 0.20 - 0.00 Apatite 0.10 0.20 - 0.00 1 r
UJ to < o yo lij
< cc
CL hi > o < X o < o a. s. tn < > < Q o O
Q: o < 00^ (/5 Q _i Nl UJ (- U. a: I < X a (/) o Q. I UJ if) < o o o CM <
Q: < O o u. o
< in cr o < o o > CM cc < z. (r o UJ
4 o o 09 (D o on en tn Q _i UJ u. IB
It is evident from the Table that the quartz is the most abundant mineral in the granite, comprising 33.03%/ the next dominant mineral is K-feldspar which constitute
29.18% of the rock and this is followed by plagioclase with an average modal value of 26.76%. The modal quartz-potash feldspar-plagioclase feldspar (recalculated to 100%) was plotted on the orthoclase-albite-quartz ternary diagram
(Fig. 3). The plots are scattered in the ternary diagram/ no systematic variation corresponding to the geographical location is observed. This diagram, superimposed on the
Strekiesens (1976 J classification scheme (Fig. 4), shows that the granite ranges from normal alkali granite field to granodiorite field.
Petrography
Quartz is the most important constituent of the rock/
they are generally strain-free, fresh and unaltered, with a
euhedral shape (Fig. 5). Quartz grains vary in size from
fine to coarse. Thin veins comprising of small crystal of
quartz and feldspars fill in the irregular fractures within large feldspar crystals (Fig. 2). Small grains of quartz il
tsl cr < ID a
'in\ 18
FIG: 2 IRREGULAR FRACTURES IN K-FELDSPAR FILLED BY THIN VEIN OF SILICIC MATERIAL.
FIG: 5 FRESH AND UNALTERED POLYGONAL QUARTZ. 19
occur as inclusions in rnicrocline and plagioclase crystals
(Fig. 6). Sometimes, they also occur as veins within feldspar crystals (Fig, 1), Coarse quartz crystals occur in clusters of plygonal shape with triple point junctions exhibiting mosaic texture (Fig. Q). They are probably recrystallized quartz grains. Effect of deformation on quartz grains is marked by the elongation of quartz and development of foliation,* such quartz grains have undulose extinction (Fig. 9).
K-feldspar is the next major mineral constituent of the rock,* its modal value is 29.18%. It dominates over the plagioclase feldspar which constitute 26.76% of the rock.
Generally, K-feldspars are rnicrocline, very few small grains of orthoclase are also present. Microcline crystals are large and fresh. The crystals are deformed and fractured,* the fractures are filled with silicic material. The large
grains are sometimes granulated at the boundary imparting a mortar structure. The K-feldspars are generally perthitic,*
fine lamellae of albite, formed by replacement of microcline, are included within the minerals. All the albite grains within microcline have similar optical orientation as that 20
FIG: 6 INCLUSIONS OF QUARTZ IN K-PELDSPAR
L '4 ' % - K^^|^e> HFI^ ' r^^»>. -i^ F •^L, *^B 1 ^ FIG: 7 QUARTZ V|]INS IN MICROCLINE. 21
FIG: 8 RECRYSTALLISED QUARTZ GRAINS
FIG: 9 ELONGATED QUARTZ GRAINS PARALLEL TO FOLIATI ON 23
FIG: 10(a,bJ PLAGIOCLASE GRAINS SHOWING BENDING, - FRACTURING, AND DISLOCATION OF TWIN LAMELLAE. 24
muscovites are well oriented along the cleavage planes,
Some plagioclase crystals are completely covered by flakes of sericite and muscovite. Parallel banding and veins of sericite and muscovite are present along parallel fractures and margins of feldspar grains (Figs. 11 and 12), These vein like branches of sericite and muscovite along fractures in feldspar grains are attributed to the action of fluid in the process of mineral alteration (Roy et al,
1985J . These muscovite and sericite grains are secondary, a product of mineral alteration. The calcium released from feldspar in this process formed fresh calcite which either occur along the margins of large feldspar grains or in the veins of polygonal quartz aggregates (Roy et al,
1985). Due to extensive alteration, the rock appears as a sericite and quartz aggregates (Fig, 13). Some crystals of muscovite in the rock are, however, of primary origin,
Gangopadhyaya (1961) suggested that the twin ccxnposition planes in feldspar grains are parallel to the conjugate shear planes and that the twining in the conjugate grains are the result of intergranular gliding along shear planes due to flattening normal to foliation. This suggests that the 23
FIG: 11 BAND OF SERICITE ALONG FRACTURE IN FELDSPAR
FIG: 12 BANDS OF SERICITE AND MUSCOVITE ENVELOPING THE FELDSPAR CRYSTAL. 26
twining in plagioclase is secondary and has developed as a result of post-crystallization deformation. The twining follows albite law, sometimes combination of albite and pericline law (Fig. 14^.
Accessory minerals include muscovite, biotite, sphene, chlorite, apatite, and zircons. Muscovite content in the rock ranges from 0.6% to 13.2% (Average 6,1%J in sample
No, 13 it is lowest (0.6%) and highest in sample No, 15
(13.2%j. Excluding these two samples, they vary from 2.01% to 8,8%. Inclusions of apatite in the biotite grains are present (Fig, 15J. Sphenes are generally euhedral in shape.
The field observation corroborated by the petrographic study indicates the presence of a uniform homogeneous type of granite in the area,
Gorai (1951J classified the plagioclase twining into two types A-type and C-type, A-type twining is found both in igneous and metamorphic rocks, whereas C-type twin develop in crystals during growth and is restricted in magmatic rocks,
Absence of zoning and C-type twining in plagioclases suggest a metasomatic origin of granite. However, presence 27
FIG: 13 AGGREGATES OF QUARTZ GRAINS SURROUNDED BY SERICITE.
FIG: 14 PLAGIOCLASE GRAIN SHOWING COMBINATION OF ALBITE AND PERICLINE TWINING. 28
FIG: 15 INCLUSION OF APATITE IN BIOTITE GRAINS 29
of limestone xenoliths in granite, and the intrusion of granite liquid along fractures in limestone blocks is evidence of magmatic origin of granite. Granite is highly deformed marked by the bending of twin lamallae, strained crystals of plagioclase and untwinned plagioclase crystals.
It may be possible that the zoning and C-twins were destroyed during later deformation and alteration of plagioclase. As such, it is inferred that the granite was emplaced in a liquid state and hence of a magmatic origin. 30
CHAPTER - IV
GEOCHEMISTRY__OF_THE_GRANITE
The petrological studies alone may not be adequate to
decipher the petrogenetic history of the rock. Geochemical
finger print provide important information regarding the
chemical behaviour during the geological processes and are
also helpful in deciphering the sequence of events involved
in the rock formation. The study of the fractionation of
certain major and trace elements can be used to construct
the petrogenetic model and to determine the composition of
source region from which they have been derived.
Rare Earth elements. Isotopes, trace elements and their
ratios are very helpful in the study of the petrogenesis of
the rock and composition of source region. Hanson (1978),
McCarthy (1976, 78;, El-Bouseily and El-Shokary (1975) and
others have successfully used trace elements, particularly
Rb, Ba, Sr, and Ti and their ratios to decipher the origin
of the granitic rock and their crystallization history.
Pearce et al (1984; used Rb, Y, Yb, Nb, and Ta for the
tectonic interpretation of granitic rocks and classified 31 the rocks into various types according to their tectonic
setting. The granites have been classified into I-type and
S-type, depending upon their source of origin on the basis
of K 0/lSla^O ratio and Silica content by Chappell and White
(1974K
Major oxide and trace elanent geochemistry of the Ahar
River granite was carried out to determine the ccanposition
of the rock and its origin, whether S-type or I-type. Such
type of study has not been carried out on Ahar River granites
by the earlier workers.
Geochemical Analysis
Ten representative samples of Ahar River granite were
selected for chemical analysis to determine the major and
trace element composition of rock. Major and trace elements
were analysed by the rapid analysis method of Shapiro and
Brannock (196 2;, the U.S.G.S. standards CM, GR and GSP
were used as reference.
One gm of sample was digested with hydrofluoric acid
and perchloric acid, and then it was transferred to 100 ml
volumetric flask to prepare the standard solution which was o ^
used to determine the concentration of major elements,
Na^O, K„0, CaO, MgO, Total Iron, and MnO on Double Beam
Atomic Absorption Spectrophotometer. Trace elements, Rb,
Ba, Sr, Cu, Co, Cd, Ni, Zn, Pb, and Li were also determined
on Atomic Absorption Spectrophotometer directly from standard
solution. Solution A was used to determine the concentration
of Si02 and A120T in the rock," it was prepared by fusion of
0.1 gm of rock powder with NaOH pellets in nickel crucible.
The solution was mixed with 111 HCl and then transferred to
one litre voliometric flask. The concentration of SiO„ and
AI2O0 was determined by Spectrophotometer using colour ions
of respective elements and measuring the absorbance on
selected wavelength 6 40 mM for SiO^ and 47 5 mM for Al„0 .
The result of major oxide elements and trace elements are
presented in Table (4J.
Major Elements
It is evident from Table 4 that the concentration of
SiOp is generally high and does not show much variation,* it
ranges from 72.16% to 77.6%. The amount of A1„0 is also
fairly uniform, it varies from 14.37% to 18.29%. CaO, Fe^O O 00 00 rH «* 00 << o CO CN iH 33 r- o o o o 1 O) ro i£) *£) rH o o o CTi
O (N •^ (X) ro CO 00 CN r-i ro O VO iH VD <* o 1 CN in -* CN O CTv o o ON
VD O 0> CTi -H 00 r- n in -* •* ^ ro o o 1 X5 CM ^ CM CO 4-1 o o o CTi G O U r- vO o o >* CO rH VD LD ID I^ r-i in rH CD ro o o r-\ in in ro ro o o o o CTi
00 in CO a\ CN VD CTi CO VD <• CN rH O VD r-\ M \o 1 0) rH •=* in <* ro o o O CO a r- rH ON
Z i£> M) in ro CO -* CN rH in 0) en r- CN in VO VD CN CN r-i LD o r-( (N U3 ^ CN O a, o o o CTi CO in 00 <-i CO ion ro- CN ia\n CN in o < o 1 VD in <:)< ro CO o O o 1 r- fH
^
t-i a> r-{ CN ro
rH in vD in in CTi 4* in H VO •* in «* in fO H r- 1 (M in ^ r-i O O O o rH o
•P G
rx5 5^ ro O CN D O O CN CN CN O +J o (0 CN o(0 Q) D< oG O 2 •H PM CO o s: S r- VD VD CN y£> vo O VD ro cr> VD 34 VD IT) CD VD r- a\ O 0> VD ro in ro VD in CN rH VD r~- r- in CX) in CM ON CN o CM cy> in ro rH <* oC u in CO 'I' •* r-{ in in VD 00 CTi r- ro t in 00 ^ VD CN ro •* CM ro rH 13 -P C I 0 0) u VD in cr. in ro ro O o r~ in CN a in in CM ro rH 00 in CM rH CN E-« in CN O o o\ in CN r- rH o CO r- \D r^ ro O ON 00 0) r-H a\ CN -H CN CO in r- ro r- ro in CTi 00 VD -* rH H CO ro cr» CO o CO ro r~ VD rH 00 ro ^ ro in CN iH ro CN CN rH ^ VD (Ti 00 o o r- VoD CN VD .H 00 CT> CN CN rH CN ro VD O (T\ in ro VD in CN CN CN in ro 00 r- ro CO in O ro rH rH «1 -P G Q) o M u X) o •H M en u >-3 OK U .^ o VD 00 rH ro m iH rH ^i* r-{ CO m CM • • t • • • CM CoN VD (N O o o n o VD a\ r- CN n in CN VD in CM r-t CM « • • • • • CM O no rH VD o r-l o r- in r-{ n ^ O in r-H 00 VD r~- rH n t • VD • • • • CM CM O ro o 00 rH o 00 VD 0)1 vo >* O t^ cr» VD O r~- CO tn O -H rH » » O • • • • CM O CM CM CN ro O o rH (U! r-ll M '^ a\ t-~ r- in CN in CM *o* CO 00 H • • O • • • • (N n O ro r-i o CN o in H o on rH O O r-\ r- VD CO 'l' r-t • • O • • • • CN i-t '^ O CN o in O M c^ a\ CM VD «* in <* CM 00 rH • o• in • • • t iN iH m VD rH o CM o VD CN in vD rH < O •^ fO CM in CN t r- in • CTv • • • • CN O CN O CO in o H CO CO c^ r~ ^ H og n ^ -* CJ\ i-i CM • • Ca\O • • • • CM o CM o '^ en o •P o M g CN (0 XI (0 u XI u o ^ ^ M CN ft) ^ <; i4 aCC CQ CO 36 and MgO contents in the rock are low, constituting less than 1%. Concentration of Na20 is higher than that of K 0. The alkali content, however, varies in relation to the contact of the granite with limestone,* at the contact, the concentra tion of Na^O is maxim\am and K^O is lowest e.g. sample No. 27 which has Na20 content of 6,28% (highest value) and 1.01% K^O (lowest value) in the rock. The total alkalis (Na^O and KjO) in the rocks do not vary much (Fig. 16). The inverse relationship in the Na and K concentration in the granite would suggest that K has been replaced by Na at the contacts. Presence of replacement perthites at the contact corroborates this inference. Concentration of MnO is very low (generally below detection limit)," it was detected only in three samples. Major oxides, plotted on Markers diagram (Fig. 17), do not show any systematic variation or significant relationship, Na^O and K^O plots (Fig. 17) show an inverse relationship,* samples with higher Na20 have a lower K^O concentration. The K-feldspar (microcline) crystals are perthitic,* similar optical orientation of the included plagioclase crystals within the host microcline suggests an ionic exchange of Na with K to form the perthite. The variation trends of CaO, 37 7A 76 80 Si 02 (Wt.7o) FiG. 16 PLOTS OF TOTAL ALKALIS vs.Si02 OF THE AHAR RIVER GRANITE. 38 20-5 + 6^10 ; ix. i ! 20- I O10 o0-5 « U 3 2T o CM ' ^ o 70 71 72 73 7A 75 76 78 Si02(wt.%) * FIG. 17 VARIATION DIAGRAM OF MAJOR ELEMENT OXIDES AS A FUNCTION THE Si Oj CONTENT OF THE AHAR RIVER GRANITE 39 Fe^O^, and MgO do not show any significant relationship. The major oxides, plotted against Solidification Index (S.I.J on Figure 18, do not reveal any trend or relationship. When the major and trace element data, plotted on Marker's variation diagram, do not show any clear relationship, this indicates that the rocks are not probably related with the simple fractional crystallization of a common parental magma or partial melting of a common homogeneous source (Schuster et al, 1985J . The Ahar River granite has a molar concentration of AljO in excess of CaO + .Na^O + K O and hence may be termed as peraluminous (Shand, 19 50J , The K^O increases in the granite reciprocally to Na^O resulting in the variation of K20/lSfa20 ratio from 0.16 to 1.1. The plots on Na^O vs K„0 diagram (Fig. 19 J reveals that the granite varies from tonalite to adamellite in composition, ^^2^ ~ ^2^ " ^^^ ternary diagram (Fig, 20j also shows variation in the composition of granite from tonalite to quartz monzonite. However, the plots on Figure (2J) are more concentrated towards granodiorite than tonalite fields. As mentioned earlier, there is evidence of exchange of K and Na ions in the rock. 40 o 2 1 ^ 0 • •• «• ••• • • • 1 •• • \* • • 0 • o 2 o • 1 - • • o a . •• ••• . 0 —•• A • • • • • • • o 2 - • rsi • it: • 0 8 - • 6 • • • A • • • o • • • csj a 2 0 • • • • •• • 15 • •• O < *10 0 e • • • CO • • • 70 1 1 1 1 1 1 1 1 1 0 0.5 10 15 20 2-5 30 3-5 AO A-5 50 S. I . ^ FIG. 1 8 PLOTS OF MAJOR ELEMENT OXIDES AGAINST SOLIDIFICATION INDEX (S- I.) OF THE AHAR RIVER GRANITE . 41 UJ 2: < o rr UJ > Q: < X < UJ U- o CO 1z— UJ \-'z o o o O CNl c O z z O Z o o -J CT) «— o cr> un CNI 42 K,0 \-60 \ 30/ "^-^ GRANODIORITE ^-70 TONALITE -80 -90 Na20 70 60 ^ 50 £.0 30 20 FIG. 20 K20-Na20-CaO PLOT FOR AHAR RIVER GRANITE 10 CQO 43 In view of this, the inference based on K„0 - Na^O concen tration in the rock may not be reliable. Chappell and White (1974J studied the granite batholith of Tasman orogene zone of eastern Australia. They classified the granites into I-type and S-type depending upon their source of origin. A number of criteria to differentiate the granite into I-type and S-type have been suggested by thon. I-type granites are derived from igneous material and this is characterised by high sodium content. High Na/K and high total Na, K and Ca in relation to Al are characteristics of igneous rocks. These characteristics are retained during the generation of granitoid magma. I-type granites have low 87 86 initial Sr /Sr ratios (0.708), high oxygen fugacity and thus high ferric/ferrous ratios. Fractionation of a mantle derived basaltic parent magma produces an I-type granite,* as such, it tends to occur in a broad compositional spectrum from basic to acidic. Characteristic minerals present in I-type are biotite, hornblend + sphene + magnetite. Such granites are much more regular in chemical and isotopic 4i composition because they are derived from a more homogeneous source. Whereas, S-type granites are derived from a source region within the continental crust. S-type contains low Na and low Na + K + Ca/Al ratio, because Na and Ca are released during weathering processes and are removed in solution. Clays, formed by weathering, absorb K during diagenesis and sedimentation resulting in the formation of a pelitic sedimentary rock which is strongly peraluminous, i.e., Al/(Na+K+CaJ > 1.1 and has low Na/K. This characteristic is retained during the production of S-type granite magma from this source. 87 86 Magmas of S-type granitoids contain high Sr /Sr ratios 18 and are enriched in 0 (oxygen isotope) composition because cirustal rocks have high concentration of Rb/Sr ratio and 18 high 6" 0 in conparison to mantle (Neil and Chappell, 1977J . The fractionation takes place over a more limited range of silica content to produce various S-type granites from crxistal melt. The characteristic minerals are biotite + muscovite + cordierite + garnet + ilmenite, S-type granite exhibits more compositional irregularities than I-type because metasedimentary 45 source are more heterogeneous (white and Chappell, 1977). This classification corresponds with the magnetite series granite and ilmenite series granite as proposed by Ishihara (1977J. Hine et al (1978) studied the kosciusko batholith of Australia and used Na20 vs K^O plot which characterises the most fundamental chemical difference between the I and S-type granitoids. The more potassium rich S-type have lower concentration of sodium. The distinction between two groups is very clear. This is a useful criteria in recognizing I- and S-type granitoids (White and Chappell, 1974). Pelitic rocks have high K concentration in relation to Na and Ca (Turekian and Wedephol, 1961,* Kolbe and Taylor, 1966) and this is reflected in the high K/Na ratio of S-type. This is also exhibited in the AI2O2 / (Na20 + K 0 + CaO) > 1.1 values of S-type for kosciusko oathplith. Hine et al (1978) inferred that Al/(Na+K+Ca) < 1.1 designates I-type. Sandar and Alan (1986) used this criteria for Cheticamp pluton which has an affinity with the S-type. Hine et al (1978) differentiated the I-type and S-type 4fi • 6 - - • I-Type • • 5 -Type • • • • o • CM -J — O 3 1 , 1 1 . i 1 1 1 1 1 -U 0 3 A 5 ^20 ( Wt.7<.) - FIG. 21 PLOTS OF AHAR RIVER GRANITE ON K2O : Na2 0 DIAGRAM OF R. MINE et al (1978). 47 granites by mineral composition,* the I-type comprises of plagioclase + hornbland + biotite whereas, biotite + plagioclase or biotite + plagioclase + cordierite is characteristic of S-type. The plots of the Ahar River granite on Na^O vs K^O diagram (Fig. 21) fall in the I-type field. However, the Al^O^ / (Na^O + K^O + CaO; ratio which is > 1.0 indicates peraluminous characteristic of the rock. All the points on A/KCN vs SiO^ diagram (Fig, 22) are concentrated in the field of S-type. Sandar and Alan (1986 J applied this diagram to differentiate the peraluminous from metaluminous field. The S-type nature of granite is also inferred from the plots of data on Al-Na-K, Ca and Fe + Mg diagram (Fig. 21). Na^O vs K2O plots for the classification of I and S-type granite may not be acceptable in the case of Ahar River granite because there is evidence of K ion replacement by Na ion, whereby the concentration of sodium was increased. Trace elonent distribution in a given rock is related to their concentration in the parent magma and the crystallization 48 c o O 00 u. CD Q. 3 I ° u •- o o < 00 ©i + o CM iij O < ID 9 ^ CM O CO < O CNJ UJ CN a. o < O >• U_ CO O if) o < CN eg I • I I I • I o LL. CNI CO CX) C71 en (- o o m o UJ X Q: lu o ai LL Q: UJ 1° ^ Q a: o u o Q 2 < o O o z is:" lij I _j o m 2 2^ or u. o o X I to 2: < cr u s I— Q UJ S 0- 2 O CO < O —J a o g ° i < t^ o o u tr> UJ h- 2 < or o ** Q: Q: CM o u. o o 50 history of the rock. Depending upon the prevailing conditions, a magma may follow different trends of crystallization. McCarthy (1976 J described two extrane types of crystalli zation in a plutonic environment. One of these types is a perfect equilibrium crystallization in which the entire solid phase remains in equilibrium with the melt throughout the crystallization. This type of crystallization results in a solid of homogeneous composition, both mineralogically and with respect to major and trace element abundances. The other type is a perfect fractional crystallization where only the surface of the crystal is in equilibrium with the melt. During the crystallization, early formed solids are enriched in compatible elements,' however, the abundance of such elements decreases in successively formed solids. On the other hand, incompatible elements are present in low concentration in early formed solids but their concentration increases in successively formed crystals (McCarthy and Hasty, 1976). During crystallization of a granitoid melt, Ba, Sr and Ti are highly compatible with the solid (McCarthy and Hasty, 1976/ Hahn Weiheimes and Ackermam, 1967). 51 Between these extremes, lies a continuxim of crystalli zation involving partial equilibrium between solid and melt. Crystallization within this continuum has important consequences on the distribution of trace el orients in the resultant solids (McCarthy and Hasty, 1976). Trace el^nent data of Ahar River granite was plotted on various diagrams to determine the variation trends of elements, their mode of crystallization and nature of source from which they have been derived. Trace elements were plotted on Harkers variation diagram (Fig. 24-) to determine the variation trends of trace elements in the rock. Plots of Rb, Ba and Sr do not show any signi ficant relationship, the plots are scattered. Rb concentration in the granite varies from 42-84 ppm,* the enrichment of Rb from periphery towards centre of the granite body is significant. A good positive correlation is evident between K and Rb content in the rock. This variation is clear in KjO vs Rb plot in Figure (25). K/Rb values ranges from 201-406, the average being 317. Sample No. 15 from the contact of granite and meta- 52 • 1A00- • • • • ^1000- • a a • • S 600- • • • 200 k 125- • J ? • a • • • S 75- • • jQ • V-L- • • 25- • 1 ' 200- £ • • Q. • • - 100- • « • • • 1 I L _i„.. . 1 1 , L... 1 1 70 72 7A 76 78 80 Si02(wt.°/o) FIG. 2^ VARIATION DIAGRAM OF 5r,Rb,AND Ba, AS A FUNCTION OF THE S1O2 CONTENT OF THE AHAR RIVER GRANITE. 53 125 £ a9-7. 5 %• 25 £300 a tao 100 • •• • 1 1 1 0 1 2 3 KoO (Wt.7o; FIG 25 VARIATION DIAGRAM OF Sr AND Rb VS.K2O OF THE AHAR RIVER GRANITE . 54 sediments has unusually high concentration of Rb (127 ppm) whereas, very low content of Sr and Ba, 50 ppm and 255 ppn respectively. The anomaly in the concentration of Rb, Ba, and Sr may be attributed to the effect of contact meta somatism. Interaction of granitoid with ground water on a massive scale could cause redistribution of trace elements (Taylor, 1971 J. It has been shown, for example, that the whole rock Rb content increases with the degree of propyl!tic alteration in porphyry copper deposits, while the Sr content decreases (Olade and Fletcher, 1975K Similarly, Rb may have been enriched and Sr depleted in sample No. 16 at the contact,* as such, the sample has been disregarded. Sr and Ba substitute potassium, especially at the later stages of magmatic crystallization. The concentration of Ba is high in the rock,* it ranges from 256-1311 ppm (Table 4j . Towards the central portion of the rock body, Ba concentration increases, whereas near the contact of granite with meta- sediments, Ba is depleated in the rock. Sr concentration in the granite is higher towards limestone contact but the value decreases at the contact of metasediments. The concentration of Sr in the rock varies from 71-260 ppm. 55 The distribution pattern of Rb, Ba, and Sr shows that the crystallization of Ahar River granite did not occur by the equilibrivim mode. Same type of fractional crystalli zation is more likely to have taken place. As suggested by McCarthy and Hasty (1976), during the fractional crystalli zation of a granitoid melt, concentration of Ba, Sr, and Ti are high in early formed solids because they are compatible elements. Their abundance falls in the successively formed solids. Central portion of the Ahar river granite has higher abundance of Ba and Sr than the periphery. It may be inferred that the central part of the pluton crystallized first and the peripheral body formed by later fractionated magma. The low content of Ba, Rb, and Sr towards the contact with the country rock may also be due to later metasomatism. Calvin (1985) suggested a pelitic source of magma if the Rb/Sr ratio > 0.5 (which is higher than average crustal ratio). Average Rb/Sr ratio of Ahar River granite is 0.53. K/Ba varies from 15.76 to 41,73 and Ba/Rb ratio varies from 6.13 to 18.57 . Cr, Ni, Zn, and Pb concentrations in the rock are high. Ni and Cr show positive trend with silica, whereas Zn has a 56 , eof 70 ^ 60 S 50 2 ^0 30 425 ^-,00- 375 \ 350 1 325 300 |275 a 't:250 o 225 2\) 175 - 300 - 275 - 250 - 225 - 1 1 200- 1 „175 _ E Q. al50 N125 - 100 ~ 75 - 50 ! 70 71 72 73 74 75 76 77 78 79 60 SiOCWt.V.) » FIG: 26 VARIATION DIAGRAM OF Zn,Cr,AND Ni, AS A FUNCTION OF THE S1O2 CONTENT OF THE AHAR RIVER GRANITF . 57 negative correlation (Fig. 26^. Li, Cu, Co, and Cd have uniform distribution. Plots of Pb vs SiO^ shows large scatter of points, El-Bouseilly and El-Shokkary (1975J plotted the Rb, Ba, and Sr values (ppm values recalculated to 100%J on a ternary diagram to determine the differentiation trend of the granitic rocks. The ternary plots of Rb, Ba, and Sr for Ahar River granite (Fig. 21) are concentrated in normal granite field and are confined to the Ba apex of the ternary diagram. Turekian and Wadephol (1961-) termed such rocks as low Ca. granites. Taylor et al (I960) opined that they are typically associated with high temperature (least differentiatedJ K-feldspar in normal granite. Heier and Taylor (19^9) studied the distribution pattern of Rb, Ba and Sr in alkali feldspar and observed that in a differentiation series, Ba decreases more rapidly than Sr. As such, Ba/Sr ratio decreases with increasing fractionation. From the ternary diagram, it is evident that the rock is not much differentiated. Criteria for classification into I and S-type is given by White and Chappell (1974J. Geochemical and mineralogical 58 100 MOr,. FIG. 27 DIFFERENTIATION TRENDS OF THE AHAR RIVER GRANITE AFTER EL-BOUSEILLY AND EL-SOKKARY (1975). 59 characteristics of Ahar River granite correspond to S-type granite. The granite has high silica content, 72-77%. AI2O3 / (Na^O + K2O + CaO) is more than 1.1 which reveals its peraluminous composition. These characteristics are identical with the Kosciusko Batholith of Australia (Hine et al, 1978) and Cheticamp pluton of Nova Scotia (Sandra and Macdonald, 1986J which have been identified as S-type. Presence of biotite and muscovite and absence of hornblende with apatite and zircon as accessopy minerals signifies its affinity with S-type. K^O / Na20 ratio are modified by the exchange of K with Na ions . Peraluminous composition and characteristic mineralogy of Ahar River granite indicates its affinity with S-type granite. The limestone and granite relationship indicates intrusive nature and magmatic origin of the Ahar River granite. Lime stone xenoliths in the granitic rocks, and presence of granitic veins indicates a magmatic origin of the granite. These granitic veins have physical continuity with the granitic pluton. The peraluminous nature of the granite as revealed by the geochemical study suggests anatexis of aluminous sedimentary rock which formed the granitic liquid. 60 CHAPTER - V SUMMARY AND CONCLUSION The granitic rocks exposed towards northwest of Udaipur city was designated as Aplogranite by Heron (1953;. He concluded that the granitic rocks correspond to post-Aravalli but pre-Delhi igneous intrusions . The granite was designated as the most instructive intrusion in the Aravalli rocks. Aplogranite was later termed as Ahar River granite by Crawford (1970) who calculated their age as 227 5 M.Y. by Rb-Sr method. The Ahar River granite has been considered to be synorogenic in nature (Anon, 1981;. Roy and Paliwal (1981; and Roy et al (1985^, on the basis of regional lithological correlation, consider the granite as pre- Aravalli basement rocks. Field relationship of granitic rocks with Aravalli limestone suggests a magmatic origin of the granite. Presence of limestone xenoliths in the granitic rocks and the granitic material in limestone along fractures indicate intrusion of granite into limestone. The granite is highly sheared and fractured. Dislocation, fracturing and bending 61 of plagioclase twin lamellae indicates post-crystallization deformation. The rock varies in composition from normal alkali granite to granodiorite. The petrographic study, however, reveals a homogeneous composition of the rock. Quartz is the most abundant mineral in the rock comprising 33.03%, followed by K-feldspar and plagioclase their percentage are 29.18 and 26.7 6 respectively. K-feldspar show perthitic intergrowth which is formed by the replacement of K ion with Na. All albite lamellae are extinct at the same time on rotation of microscope stage. Among accessory minerals muscovite, biotite, chlorite, sphene, apatite, and zircon are present. Presence of primary muscovite and absence of magnetite and hornbland shows mineral characteristics which has affinity with S-type (Chappell and White, 1974J. Geochemical data plotted on Si02 variation diagram, reveals that they are not formed by the simple fractional crystallization. The plots of Rb-Ba-Sr ternary diagram shows that the granite is not very much differentiated and lies in normal granite fields. The granite is inferred to be S-type as indicated by silica content (range 7 2.16% - 62 11.6%); high Al / (Na + K + Ca; > 1.1, plots of data on Al - Na - K, Ca and Fe + Mg diagram, and presence of primary muscovite. High molar proportions Al / (Na + K + Ca) > 1.1 indicates peraluminous nature of the magma. The magma was derived by the anatexis of aluminous metasedimentary rocks, which produces granitoid rocks of S-type. 63 Anon, (1981)1 Explanatory brochure to the geological map of the Aravalli region, southern Rajasthan and northeastern Gujarat. G.S.I. Pub. pp. 1-38. Calvin, F.M., (1983)1 Are strongly peraluminous magmas derived from pelitic sedimentary sources. Jour, of Geology, v. 93, pp. 67 3-689. Chappell, B.W., and White, A.J.R., (1974)1 Two contrasting granite types. Pacific Geology, v. 8, pp. 173-17 4. Chaudhary, A.K., Gopalan, K. and Sastry, C.A., (1984)1 Present status of the geochronology of the Precambrian rocks of Rajasthan. Tectonophysics, v. 105, pp.131-140. Chayes, F., (1956)1 Petrographic Modal Analysis. Wiley and Sons, New York, pp. 113. Crawford, A.R., (1970)1 The Precambrian geochronology of Rajasthan and Bundelkhand, Northern India. Cand. Jour. Earth Sci., v. 7, pp. 91-110. 64 £l-Bouseilly, A.M. and El-Sokkary, A.A., (197 5): The relation of Rb, Ba and Sr in granitic rocks. Chem. Geol., v. 16, pp. 207-219. Gangopadhyaya, J., (1961K Study on the deformation of the Precambrian granites, north of Udaipur city, Rajasthan and the development of plagioclase twin in them. Quart, Jour, Geol. Min. Metal. Soc. India, v. 33, pp. 189-190. Gorai, M., C1951K Petrological studies on plagioclase twins. Amer. Mineralogist, vol. 36, pp. 88 4-901. Hacket, C.A., (1877)1 Aravalli series in northeastern Rajputana. Rec. Geol. Surv. India, 10(2), pp. 8 4-9 2. Hacket, C.A., (1881)1 Geology of the Aravalli region, central and eastern Rajputana. Rec. Geol. Surv. India, 14(4), pp. 229-30. Hahn-Weinheimer, P., and Ackerraan, H., (1967)1 Geochemical investigations of differentiated magmatic granite plutons of the southern Black Forest, 11. The joninq of the Malsburg granite pluton as indicated by the elannents titanium, zirconium, phosphorous, strontiurr,. 65 barium, jrubidium, potassium and sodium. Geochim. Acta, V. 31, pp. 2197-2218. Hanson, G.N., (1978)1 The application of trace elements to the petrogenesis of igneous rocks of granitic composition. Ear. Plat. Sci . letter., v. 38, pp.26-43 Marker, A., (1909)* The natural History of Igneous Rocks. New York. Heier, K.S., and Taylor, S.R., (19 59, a) I Distribution of Li, Na, K, Cs, Pb and Ti in southern Norwegian Precambrian alkali feldspars. Geochim. Cosmochim, Acta, V. 15, pp. 282-304. Heron, A.M., (1935)1 Synopsis of the pre-Vindhyan Geology of Rajputana. Trans. Nat. Sci. India, v. 1(2), pp. 17-33. Heron, A.M., (1953)1 Geology of central Rajputana. Mem. Geol. Surv. India, v. 79. Hine, R., Williams, I.S., Chappell, B.W., and White, J.R., (1978)1 Contrast between I- and S-type granitoids of the Kosciusko batholith. Geol. Soc. Australia, V. 25, no. 4, pp. 219-234. 66 Ishihara, S., (1977 K The magnetite-series and ilmenite- series granitic rocks. Ming. Geol., v. 27, pp.293-305. Kolbe, P. and Taylor, S.R., (1966K Geochemical investigation of the granitic rocks of the Snowy mountain area. N.S.W. Jour. Geol. Soc. Aust., v. 13, pp. 1-25. McCarthy, T.b., and Hasty, R.A., (1976K Trace element distribution patterns and their relationship to the crystallization of granitic melts. Geochim. Cosmochim. Acta, V. 40, no. 11, pp. 13 51-13 58. McCarthy, T.S. and Fripp, R.E.P., (1978)*. The crystalli zation history of a granitic magma, as revealed by trace elenent abundances. Jour, of Geol., v. 88, pp. 211-224. Olade, M.A., and Fletcher, W.K., (1975)1 Primary dispersion of Rb and Sr around porphyry copper deposits. Highland valley, British Columbia. Econ. Geol., v. 70, pp.15-21 O'Neil, J.R. and Chappell, B.W., (1977K Oxygen and hydrogen isotopex relation in the Berridale batholith. Jour. Geol. Soc. London, v. 133, pp. 559-571. 67 Pearce, J.A., Nigel, B.W.H. and Andrew, G.T., (1984): Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Jour. Petro., V. 25/4, pp. 956-983. Roy, A.B. and Paliwal, B.S., (1981JI Evolution of lower Proterozoic epicontinental sediments I Stromatolite bearing Aravalli rocks of Udaipur, Rajasthan, India. Precambrian Res., v. 14, pp. 49-7 4. Roy, A.B., Golani, P.R. and Bejarniya, B.R., (1985;: The Ahar River granite, its stratigraphic and structural relations with the early Proterozoic rocks of south eastern Rajasthan. Jour. Geol. Soc. India, v. 26, no. 5, pp. 315-325. Ruperto, V.L., Stevens, R.E. and Norman, M.B., (1964JI Staining of plagioclase feldspar and other minerals with F., D., and C. Red No. 2, U.S. Geol. Surv., Profess, paper 50/B, B-152-B-153. Sandra M. Barar, Alan., S. Macdonald and John Blenkinsop, (1986JI The Cheticamp plutonI a Cambrian granodiorite intrusion in the western cape Breton Highlands. Nova 6 Scotia. Cand. J. Earth. Sci ., v. 23, pp. 1686-1699. Shuster, R.D. and Bickford, M.E., (1985K Chemical and isotopic evidence for the petrogenesis of the north eastern Idaho batholiths. Jour. Petro., v. 93, no. 6, Shand, S.J., (1950;! Eruptine Rocks. Wiley, New York, 4th edition. Shapiro, L. and Brannock, W.W., (1962K U.S. Geol. Surv. Bulletin, 1144-A. Streckeisen's, A.L., (1976K To each plutonic rock its proper name. Earth Sciences Review, v. 12, pp. 1-33. Taylor, S.R., and Heier, K.S., (1960J : The petrological significance of Trace Elment Variations in alkali feldspars. 21st Int. Geol. Congr. Copenhagen, Rept. pt. 14, pp. 47-61. Taylor, M.P,, (1971K Oxygen isotope evidence for large scale interaction between meteoric ground water and tertiary granodiorite intrusions. Western Cascada Range, Oregon I Jour. Geophys. Res., v. 76, pp. 7855-7874. 69 Turekian, K,K. and Wedephol, W.H.^ (1961): Distribution of the elements in some major units of the earth's cxnast, Geol. Soc. Amer. Bull., v. 7 2, pp. 17 5-192 White, A.J.R. and Chappell, B.W., (1977K Ultrametamorphism and Granitoid Genesis. Tectonophysics, v. 43, pp. 7-22. "i:^^M^.:^psi^f^ Uvs^ini 'U ^5^^ >-^ '•A-