STRUCTURAL AND METAMORPHIC STUDIES OF THE ARAVALLI ROCKS IN PARTS OF ADKALIA, UDAIPUR DISTRICT, RAJASTHAN
DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF iHaiSttr of Pliiloiopiip IN Hi GEOLOGY
r\ ' "i
BY MD. AHMAD ZIYA MALLIK
DEPARTMENT OF GEOLOGY ALIGARH MUSLIM UNIVERSITY jf'. ALIGARH (INDIA) 1995 DS2973
.IfUfllMVJW CONTENTS
PAGE NO.
ACKNOWLEDGEMENT
LIST OF FIGURES
LIST OF TABLES
CHAPTER - I INTRODUCTION 1-7
CHAPTER - II STRATIGRAPHY, LITHOLOGY AND STRUCTURE 8-16
CHAPTER - III PETROGRAPHY AND METAMORPHISM 17-25
CHAPTER - IV DEFORMATION AND STRAIN ANALYSIS 26-49
REFERENCES 52-59
DESCRIPTION OF PLATES 60-61
ANNEXURES 62-65
********* ACKNOWLEDGEMENT
I acknowledge my deepest gratitude to my supervisor
Dr. Syed Ahmad All, Lecturer, Department of Geology, Aligarh
Muslim University, Aligarh, who guided me and gave
invaluable suggestions time to time.
It gives me pleasure to express thanks to Prof.
Iqbaluddin, Chairman, Department of Geology, A.M.U.,
Aligarh, for providing all research facilities.
I am thankful to Dr. Tyagi, Department of Zoology,
M.L. Sukhadia University, Udaipur for providing University
guest house facility and Dr. Shahid Farooq for taking
photographs of thin sections. Thanks are due to Mr. Mahto
of village Adkalia and to my friends Zaheeruddin, Rizwan,
Shabeer, Jamal, Shilpa, Asad and Sandeep for their help and
co-operation.
I am also thankful to Mr. S. Masahab Ali for typing
work. Last bur not least I wish to offer my sincere thanks
to my family members and well wishers for their kind
cooperation.
(MD. AHMAD ZIYA MALLIK) LIST OF FIGURES
PAGE NOS.
Fig. I Map showing location of the study 2
area
Fig. II Map showing general lithostrati- 9
graphy of Aravalli region
Fig. Ill Geological map of the study area 10
Fig.lA & IB Relationship of sphericity and Zingg 28-29
shape indices for location no.l & 2.
Fig.2A & 2B X vs Z plots for location no. 1 & 2 31
Fig.3A & 3B Y vs Z plots for location no.l & 2 32
Fig.4A & 4B X/Y vs Y/Z plots for location no. 38
1 & 2
Fig.SA & 5B e^ - 2^2 ^^ ^ 2 ~ ^3 P^°^^ ^°^ 40-41 location no.l & 2
Fig.SA and 63 Histogram showing frequency per- 42 centage of pebbles falling in K > 1, K < 1 and K = 1 for location no.l & 2
Fig.7A & 7B Polar graphs of 6:s vs ">) for 47—48
location no. 1 & 2 LIST OF TABLES
PAGE NO.
Table 1 Classification of the -Aravalli 8(a) supergroup
Table 2 p and y values of phenoclasts of 34 location no.1
Table 3 p and ~X values of phenoclasts of 35 location no. 2
Table 4 ^ s, To and S) values of location 45 no.l
Table 5 £. s, ~Yo ^"^ "S) values of location 46 no.2 CHAPTER - I
INTRODUCTION
General Statement:
The area is situated in Aravalli region of Rajasthan
and have been studied in detail with relation to Lithology,
Stratigraphy and Structural features by various authors.
Among them Naha & Halyburton 1974, Sengupta 1976,
Mukhopadhaya & Sengupta 1975 and riohanty & Naha 1986 are
most important one. AdKalia area situated South-VJest of
Udaipur become obvious choice for study because of good rock
exposure and easy accessibility so that detailed structural
and metamorphic analysis can be done.
Aravalli system has immense thickness of argillaceous
rocks varying in grade of metamorphism from Slate to gniess
through schist and phyllites. In between them igneous
intrusion are present with Limestone occurring in subordi
nate amount. Aravalli range marks the site of one of the
oldest geosynclines of the v7orld. Structurally it is a
close synclinorium of rocks and came into existence at the
close of the Dharwarian era.
Location:
TJie area under study is located at about 65 kms.
South East of Udaipur in Rajasthan. Total area studied lies 70' Hi 7*' tl* »6° 90* V -r
LOCATION V\f\? between latitude 24°08'30" and 24°09'30" Longitude being between 73°59'45" and 74°01'15" . Area is included in survey of India Toposheet no. 45 — ap^ 45 _ 4 16 Communication and Accessibility:
Udaipur is well connected from Aligarh via Delhi by
Rail. Adkalia area is easily approachable by highway road
connecting Udaipur to Banswara at about 65 km. South East
of Odaipur. Transport system in some villages around
Adkalia is good while some are approachable only by foot.
Climate:
The climate of the area is characterised by very hot
sum.mer and cold dry winter. Under Kopen's climatic
classification the climate of the area is BShw type which
means warm semi arid steppi type v/ith mean annual tempera
ture about 18°C and mean annual rainfall about 50-60 cms.
Extreme climatic condition is due to inland location, tropic
of cancer's closeness, lack of vegetation and bare rocks.
January is the coldest month while May and June are the
hottest one. Rainy season is from July to September due to
South-VJest monsoon.
Physiography:
The area has a varied topography which is the result of its geological history and various exogenetic forces which acted time to time. Lasaria Plateau, Hills of
Jaisamand and Aravalli plains are important physiographic features of nearby study area.
Drainage:
The drainage of the area is also influenced by its
geological history. Gomti, Tirri and Mahi rivers are main
rivers of the area. The river generally flow through
regional slope. These rivers are perennial and are
controlled by local structures. Important canals have been
made from these rivers to irrigate the land.
Fauna;
Panther, Leopard, Snakes, Jackals, Deer etc. can be
found in nearby forest and in some low populated areas.
Domestic animals found are Buffalos, Cows, Camels, dogs and
goats.
Flora;
Vegetation is Scanty and Shrubby and can be said to
be poor. Main vegetation is Euphorbia, Cactus bushes and
Spear grass. There is gradual increase in flora from North
to South and from East to West. Growth of Flora is more on
the slopes of the hills than near the top because of
increase in soil ana moisture content. Euphorbia, Mahua (Madhuca indica), and Karai (sterculia) are common one. Villagers and forest department have grown mango (Mangifera indica), Ber (Zizyphus jujuba), Tamarind (Tamarindus Indica)
Jamun (Eaqaria Jambolana) and Babool (Aracia arabia).
Review of Previous Work done:
Precambrian rocks in and around Udaipur and Mewar areas were first named Aravalli by riacket in the year 1881.
He was also the first man to write a paper on Aravalli mountain range. Actually Aravalli is so named on the basis of Adda and Valli, the former meaning a blockade and latter a ridge line lying in Kajasthan. Here ridge line is Great
Boundary Fault separating Vindhyans and Aravalli. HERON,
LATOUCHE & MIDDLEMISS of geological Survey of India are prominent names who have done early systematic survey of
Aravallis. HERON has observed that anaJagcus to the
Dharwarian rocks of South India. HERON, 1955 suggested four
fold classification of Aravalli system and three granitic
episodes between them. Three granitic episodes being
Erinpura, Aplogranite and Bundelkhand granite. He also
erected stratigraphic sequence of rocks through his effort.
HERON 1953 said area to be Eastern limb of major anticlinal
axis extending from Nathara Ki Pal through zawar to Udaipur.
Banded Gniessic Complex (BGC) is the basement on which
successively younger rocks of Delhi groups were deposited with Rialo Series showing unconformity (Gupta 1934 & Heron
1953; between them. The area have been studied in detail
with relation to stratigraphic and structural relation by
Naha et al 1966 ; Naha & Halyburton 1974, 1977; Roy and
Paliwal 1981; Naha & Roy 1983 and Roy et al 1985 & Mohanty
and Naha 1986.
Regarding age several Scientist determined absolute
age on the basis of Rb, Sr, Pb & K/Ar isotope. (Crawford
1969, 1970, 1975 Sarkar et al 1960, Naha et al 1967 Mishra
& Sarkar 1975, Raja Rao 1976). The age of the base of the
Aravalli supergroup is 2500-2200 m.a. Sarkar on the basis of
Ahar river granite age of Aravalli has been fixed at
1890 + 130 million years. C.A. Sastry et al (1984)
inferred that age of the Aravallic supergroup is Early
Proterozoic (2500-2200 Million Years).
Scope of Work;
Detailed structural and metamorphic study was carried out in and around Adkalia area. For detailed structural fabric analysis various strain was determined. Structural analysis was done on the basis of the analysis of
axial ratio of sample taken in three dimensions by carefully taking out pebbles. The grade of metamorphism and meta morphic texture were also studied in detail. Research Methodology;
Samples were taken as far as possible fresh and studied in handspecimen and then taken to laboratory after marking them carefully. Detailed geological and structural mapping was done by taking map of scale 1:50,000. Important megastructures were studied. In case of pebbles axes lengths were measured in different directions. After taking samples to laboratory then sections were made and detailed petrographic and textural characteristics were studied. On the basis of the length of the pebble strain analysis was done. CHAPTER - II
STRATIGRAPHY, LITHOLOGY AND STRUCTURE
General Statement:
The rocks unit occurriny in Udaipur and adjacent districts of Rajasthan comprises of thick pile of meta- sediments with some iyneous intrusion between them. They
range in age from 2500-2000 million years exhibiting
greenschist facies metamorphism and have been named Aravalli
supergroup. (Anon, 1981)
The rocks belonging to the Aravalli supergroup
consists of phyllite, mica-schist, garnetiferous biotite
schist, metagreywacke, metasiltstone, quartzite, meta-
conglomerate, conglomeratic schist, metavolcanics, metaar-
kose, pyroclastic materials, dolomite, dolomitic marble,
phosphatic and sulphide bearing dolomite, calcareous
quartzite, carboneceous and manganiferous phyllite, calc-
schist, hornblende schist, serpentinites, amphibolites,
gniesses and migmatites.
Aravalli supergroup has been divided into various groups and formations on the basis of structural and metamorphic history, lithology and tectonic setting (Table-I). 8(a) TAIll.C:
FORMATIONAL UNITS OF ARAVALLI SUPERGROUP (ANON,1981)
DELHI SUPERGROUP
Rajnagar Fm. Shivrajpur Fm. CHAMPANER Jabau Fm. GROUP Narukot Fm. Khandla Fm. Lambia Fm.
Kadama Fm. LUNAVADA Bhuicia Fm. GROUP Chandanwara Fm. Bhawanpura Fm. Wagidora Fm. Kalinjera Fm.
SYNOKOGENIC GRANITE AND GNIESS
RAKHAHDEV ULTRAMAPIC SUITE
JHAROL GROUP DOVDA GROUP NATHDWARA GROUP Samlaji Fm. Dcvthari Fm. Rama Fm. Goram Fm. Oepti Fm. Haldighati Fm. Kadmal Fm.
BARI Khamnar h'm. KANKROLI GROUP LAKE GROUP Varla Fm. Sangat Fm. Sajangarh Fm. Panthal Fm.
UDAIPUR SECTOR TIRI SUBGROUP Banswara Fm. Zawar Fm. Rajnagar Fm. UOAIPUR Nimachmata Fm. Bor. imagra Fm. Morchana Fm. GROUP Balicna Fm. Mandli Fm. Madra Fm. Eklingarh Fm. Sabina Fm.
DEBARI SECTOR JAISAMAND SECTOR GHATOL SECTOR SAROA SECTOR
DEBARI MATON Jhamarkotra Fm. Babarmal Fm. Jagpura Fm. Kathalia Fm. GROUP SUB GP Bcrwas Fm. Dakankotra Fm. Mukandpura Fm. Kathalia Fm.
Jaisaraand Fm. Jaisamand Fm. Jaisamand Fm. Sismogra Fm. DEBARI Delwara Bm. Delwara Fm. Delwara Fm. Natharia-Ki-Pal Fm. GROUP Gurali Fm. Gurali Fm. Basau Fm.
Undifferentiated Granites and Basic Rocks
Bhilwara Supergroup > 2500 M.a.
NOTE: Fm. stands for Formation. L|THCSrRAll6RAPHY MAP OF ARAVALLI flEfiilON
PC-' Ja p—^ LUHAWADA 6(ipUP -4zf Yaip] NAtHPWARA GROUP fj<7A POVPA 6R0Vf iHAROU 6MUP
GROUf
6R0UP
-4- 2^
— 23
— SCAU — >;>n zo 10 0 JO Km L_J__1 '
/\_ftir .•» »r tf <7- .'.'• :/.- O Lu y. 0- . 0 0 a. A lu o a ^y/yyy. o h CO (—• X l\ Debari Group: Debar! group of rock consists of quartzite, mica-schist, phyllite, calcareous quartzite, dolomitic limestone, dolomite, metaconglomerate, ferruginous chert, metavolcanics and pyroclastic materials. Rocks in the Debari group have been subjected to greenschist facies metamorphism. Debari group in which study area lies has been divided into Debari, Jai samand, Ghatol and Sarda Sector. The rock types occurring from Umra in the north direction to Salumbar in South direction is included in Jaisamand Sector of Debari group. Jaisamand Sector comprises of Delv/ara, Jaisamand, Dakankotra and Babarmal formations. Quartzites, conglomerates and other harder rocks stand out while less resistant rocks like phyllites and schists generally lies at lower level. The lithostratigraphical classification proposed by the Geological Survey of India (Anon, 1981) has been followed in the study area. Various rock types occurring in the formations in the study area have been described as follows: (1) Chlorite-Quartz Biotite-Sericite Schist: Chlorite-Quartz-Biotite-Sericite Schist occurs in the vicinity of Adkalia village and is light greenish in colour. It consists mainly of chlorite, quartz, biotite and 12 sericite. This rock shows bedding plane lamination as evident by colour contrast. There is preferred orientation of chlorite and sericite parallel to AS2 foliation. Out crop is weathered and some quartz grains are elongated. (2) Conglomeratic Schist: Conglomeratic Schist occurs 100 metres east of Adkalia and is brownish in colour. It consists pebbles of quartz, quartzite and marble (Plate 1, Fig.l). The size and amount of pebbles are generally more where quartzite and marble rocks are nearer. Conglomeratic schist consists matrix of biotite and chlorite mainly. Matrix is welded and deformed. This rock unit is found repeteadly. There is also wide variation in the size of the pebbles (Annexure-I). The length of the x-axis varies from 2.8 to 14.3 cms., Y-axis varies from 2.4 to 9.5 cms. VJhile Z-axis varies from 1.4 to 5.4 cms. Pebbles are flattened in J^-, A -> plain of strain. The size and proportion of pebbles increases as we move towards east of Adkalia towards Lakapa village. (3) Garnet—Quartz- Chlorite-Biotite Schist; In this rock type Quartz and Chlorite are present constituting majority of the rock. There is also elongation of quartz grain. Mineral garnet is present showing dark greenisn colour. Garnet appears as large porphyroblast in the rock. 13 (4) Quartzite; Quartzite is important rock unit around Adkalia area. Quartzite was noted west of Adkalia. Quartzite shows variation in colour and grain size. But they are generally greyish \7hite in colour and medium to coarse grained. Quartz is the most important mineral constituting about 85% - 90% of the rock. Cementing material is Silica mainly. Stratification plane is also noticeable. (5 ) Calcareous Quartzite; Calcareous quartzite contains mainly calcite, dolomite and quartz. Quartz is present irregularly and is less whitish in colour than calcareous mineral. Some ferruginous minerals are also present in trace amount. Quartz and Calcite occurs as fracture filling. Bedding plane can be seen. (6) Marble; Marble very near to be called pure marble is also present in the study area. It is well bedded and thinly laminated. It is steel grey to whitish in colour. It consists mainly of calcite and dolomite injected by veins of silica and calcite between. 14 STRUCTURAL ELEMENTS AND HISTORY: Nomenclature of Elements; For description of folds, foliation and lineation alphabetic numerical system was adopted which are related with deformative episodes of Aravalli tectonic system. (Iqbaluddin, 1984). In this first alphabet denotes tectonic system to which it belongs and second alphabet is related to structural elements. S alphabet denotes planar tectonic anisotropy or foliation, F stands for fold and p denotes lineation. Structural elements that have been noted in the study area comprises of folds, liation and lineation which are related to AD and ADj deformative episodes of the Aravalli tectonic system (Anon, 1981), (i) Foliation: Foiliation is non-genetic term used to define planar tectonic anisotropy in which there is preferred orientation of minerals or there is mechanical homogeneity (Plat^2, Fig.3). Planar tectonic anisotropy is expressed by foliation (Darwin, 1846; Fairbrain, 1935 Whitten, 1969) or Fissility (Vanhise, 1946; Whitten, 1969) or rock cleavage (Mead, 1940; Swamson, 1942; Billings, 1954} or axial plain cleavage (Ramsay, 1967) or Fracture, Flow Cleavage (Leith, 1923) or Schistosity (Darwin, 1846; Harker, 1932) which are very close terms. They have been further named A S^, AS^ and AS^ on the basis of cross cutting 15 relationship. AS, is parallel to stratification, AS^ is pervasive and penetrative while AS is closed spaced dislocation plain (Knill,60 Richard,61). (ii) Lineation: Lineation denotes linear elements seen in rocks and denotes external as well as internal fabrics of rocks (Cloos, 1946 Mclntyre, 1950) Jones, 1959, Turner and Weiss (1963) and Whitten (1969). In rocks which underwent many phases of deformation the linear elements have variable morphology, geometry and orientation (Ramsay, 1967). Lineation parallel to b axis is denoted by Ap and lineation parallel to c-axis is denoted by Ap^. Pebble lineation can be seeen in conglomeratic Schist with major axis X showing lineation (Plate-2, Fig.3). (iii) Folds: Folds are undulations developed in the rock due to stress acted upon them. They denotes high structural complexity. In folds AF, is assigned to isoclinal acute angle fold, AF, denotes open to close moderately plunging non cylindrical fold and AF denotes crenulation or axial plain cleavage in phyllites and schists. Structural History; The Structure of Aravalli around Udaipur is simple with upright folding from NNE to NE (Heron, 1953). General trend of Aravalli is NE-SW. Isoclinal, reclined or inclined fold with East or West plunge is present. Lineation, 16 stretched pebbles along folds and axial plane cleavages are well developed. Mukhopadhayay and Ghosh, 1980; Mohanty, 1982 Naha and Roy, 1983; Sengupta, 1983; Naha et al 1984 Mohanty and Naha, 1986 have studied structural complexity in detail and said that rocks around study area have been involved in four generation of folding. The structure of first two phases occur in small to large scales while last two phases in small scales only. First generation of folds are juxtaposed by set of open upright folds with north- south striking planes. Kink bands and conjugate folds were developed in third and fourth generation. 17 CHAPTER - III PETROGRAPHY AND METAMORPHISM PETROGRAPHY: Detailed microscopic study of the samples of rocks was carried out after making thin sections. Following different rock types were identified on the basis of mineral composition, texture, degree of recrystallisation and mineral paragenesis: 1. Chlorite-Quartz-Biotite Sericite Schist 2. Conglomeratic Schist 3. Garnet-Quartz Chlorite-Biotite Schist 4. Quartzite 5. Calcareous quartzite (1) Chlorite-Quartz-Biotite Sericite Schist; In this rock Schistose Structure is noted with preferred orientation of chlorite and elongation of quartz grains parallel to predominant foliation ^S,,. (i) Chlorite: Chlorite is tabular in shape amd is parallel to AS2 foliation. It is the most important constituent of rock unit. Polarisation colour of chlorite is first order blue. 18 (ii) Quartz: Quartz is next important mineral constituting about one fourth of the rock. Most of the quartz grains are elongated but some are also equant. (ill) Biotite: Biotite grains are not parallel to regional dominant foliation. Biotite is about onetenth of total. Biotite shows brownish colour. (iv) Sericite: Sericite also occurs in prismatic shape and is found at the contact of quartz and chlorite. (v) Accessory minerals: Iron-oxide, Tremolite and sphene occurs in very small amount. (2) Conglomeratic Schist: In conglomeratic schist three types of foliation is noted. First one is bedding plane AS foliation showing o compositional variation between quartz and chlorite. Second one is AS„ regional dominant foliation exhibiting preferred arrangement of chlorite and elongation of quartz in plain of strain ellipsoid (Plate-2, Fig.3). Thirdone is AS^ foliation showing closed spaced dislocation plane inclined at an angle to AS foliation. (i) Quartz: Quartz is present in about 20% - 25% of the rock. Some quartz are equant while some are elongated. 19 Equant quartz grains are found in quartz enriched layer while elongated quartz grains are found in sheet type layer. (ii) Biotite: Biotite exhibits angular relationship with AS_ foliation. Biotite amount in the rock is about 10% - 15%. It is generally found at the embayment of quartz and sericite and is lath like. (ill) Chlorite: Chlorite ranges from 50% - 60% to the total. Polarisation colour of chlorite is first order amamolous blue. Chlorite is parallel to ASp foliation. (iv) Sericite: Sericite occurs in prismatic shape and is associated with quartz and chlorite. They are fine grained. (v) Accessory Minerals: Sphene and Iron-oxides are found as accessory minerals. (3) Garnet Quartz-Chlorite-Biotite Schist: Most important phase of metamorphism that took place in garner grade is developed in this Schist rock. (i) Quartz: Quartz constitutes about 50% - 55% of the rock and two types of quartz was noted. First type of quartz is parallel to regional foliation AS^ in A,-, A ^ plane 20 of strain ellipsoid. This quartz shows strain shadows and wavy extinction. Another type of quartz is equant in shape and shows sigraoidal outline. (ii) Chlorite: Chlorite constitute about 15% - 20% of total. Polarisation colour of chlorite is analomous blue and shows faint pleochrism. (iii) Garnet: Garnet occurs as somewhat larger and appears as porphyroblast. Garnet is idioblastic and it seems that there is rotation of AS„ during metamorphic evolution. (iv) Biotite: Biotite flakes are present in small amount adjacent to quartz and chlorite. This biotite is brownish in colour. (v) Accessory Minerals: Zircon, Tourmaline, Sphene and Iron Oxide are found as accessory minerals. (4) Quartzite: Quartzite shows granoblastic texture. There is also size variation in quartz grain. Some sheet minerals occurs in intergranular spaces between quartz grains. (i) Quartz: Quartz content is about 85% - 90% of the rock. Three types of quartz were identified on the basis of relative size, optical properties and cross-cutting 21 First type of quartz is found in clastic field and is anhedral in shape. Its contact is sutured and shape is elongated (Plate-2, Fig.4). This type of quartz shows undulose extinction and is elongated parallel to regional foliation AS„. Second type of quartz is equant in shape witn polygonal outline. (Plate-3, Fig.5) On slight rotation of stage it is changed to S-shape. It is formed during development of As, foliation. Third type of quartz is subidioblastic to idioblastic and shows sharp extinction. It also exhibits triple point junction and linear contacts with adjacent grains (Plate-S, Fig.6). (ii) Muscovite: Muscovite occurs in prismatic shape and shows pleochrism of third order. One set of cleavage is seen in prismatic section (Plate-2, Fig.4). (ill) Sericite: Sericite occurs as small prismatic shape at the contact of quartz grains. Orientation of Sericite changes. (iv) Biotite: Biotite occurs as porphyroblasts and shows pleochrism in brownish green colour. It is xenoblastic in shape. (v) Feldspar: Feldspar also occurs xenoblastic in shape and general colour of feldspar is greyish white. 22 (vi) Chlorite: Chlorite also occurs as porphyroblafit Besides above mentioned minerals which are very less in amount compared toquartzare Iron-oxide, Zircon and Sphene is also noticeable. (5) Calcareous Quartzite; Calcareous quartzite shows disrupted framework in whicn there is embayment of calcire and dolomite within quartz (Plate-4, Figure-7). (i) Quartz: Quartz occurs irregularly and subrounded in habit some quartz are later replaced by calcitic porphyro- blasts. Some of the quartz shows undulose extinction suggesting metamorphic source-while other quartz shows symmetrical extinction suggesting igneous source. (ii) Calcite: Calcite occurs as xenoblastic in shape with deformed twinned lamellae. Calcite shows second and third order interference colour and is found near boundary of quartz (Plate-4, Fig.8). Crystal of calcite twinkle during rotation. (iii) Dolomite: The shape of dolomite varies from subhedral to anhedral. It shows two sets of twin lamellae and is probably found after replacing calcite (Plate-4, Fig.8). 23 (iv) Microcline: Microcline also occurs in subhedral to anhedral in shape. Its colour is greyish white and grain boundaries are diffused. It also shows cross hatched twinning, (v) Accessory Minerals: Biotite in elongated lathshape and zircn are present as accessory minerals. METAMORPHISM: Rocks of the Debari group have been deformed and recrystallised in so many phases. This polyphase deformation has changed mineral composition and texture wholly. However bulk composition of the parent rock remained same. Chlorite, Biotite and garnet are the index minerals recorded. On this basis chlorite-Biotite zone and Garnet zone of Barrcvian zone was demarked. Metamorphic Facies; Index mineral zonation can be useful guide for delienating variation m Pressure-Temperature during Metamorphic evolution (Shaw 1950; Das 68; Carniche 69, 70^ Sarkar, 82). Spatial and Structural zonation reflects the variation in the bulk composition of the parent rock (Atherton'64, Buller'65;. First zone is Chlorite-Biotite zone: Quartz + Sericite + Biotite + Chlorite Quartz + Sericite + Biotite 24 Second zone is Garnet zone: Garnet + Quartz + Biotite + Chlorite Most important metamorphism was in the Garnet grade as indicated 'by textural and microstructural relation of different minerals. In general Pressure -Temperature level in chlorite-Biotite of Debari group represents low grade regional metamorphism (Winkler, 1976). Scheme of Paragenesis and nretamorphic Recrystallisation: Metamorphic recrystallisation corresponds to AD and AD„ phase of Aravalli (Anon 1981) corresponding to which AS , AS2 and AS^ foliation developed. Metamorphic history was carried out on the basis of petrology, deformation of grains and Si-Se relation of porphyroblasts. Four Meta morphic phases were identified on above basis. 1st Metamorphic Phase; First phase corresponds to AS foliation. Quartz and Sericite developed along AS, = AS . There was ^1 o development of first type of chlorite and rotation of Sericite. First type of quartz was elongated under the influence of flattening strain. This caused development of strain shadow and undulose extinction in quartz. 25 Ilnd Metamorphic Phase; This stage corresponds to AD deformation phase which developed as AS . There was recrystallisation in \ \ 2 Plsif^ °f strain ellipsoid of allogenic quartz. (Plate-1, Fig.l) Sericite recrystallised to form muscovite while carboneceous matter was converted into Graphite. Ilird Metamorphic Phase; Crenulation cleavage in AS. parallel to AS„ foliation acting on slip developed in Schistose rock. There was rotation of porphyroblasts and shearing of Si-Se relation Biotite + Quartz - Garnet + Orthoclase Chlorite + Quartz - Garnet + Water Last Metamorphic Phase; This metamorphic phase is post-tectonic. In this phase basement recrystallisation tooK place because of rise of Ahar river Granite. There was also development of third type of Quartz, second type of chlorite and plagiclose feldspar. CHAPTER - IV DEFORMATION AND STRAIN ANALYSIS The deformed pebbles of the conglomeratic schist in the study area shows schistosity and lineation indicated by the preferred orientation of the long axes of the pebbles. The pebbles are characterised by apparent flattening to constriction in A, A o Pls"^ of strain. The long axis (X) and the intermediate axis (Y) of the pebbles lie on the schistosity plane while the short axis (z) lie perpendi cular to the Schistosity plane. This study was done to find out the type and amount of strain in the pebbles and to evaluate the parameters needed for determination of strain in two and three dimension. Deformed pebbles have been widely used for quantitative determination of finite strain in rocks (Brace, 1955; Flinn, 1956; Hossack, 1968 Burns and Spry, 1969 Oertel, 19/8 Roy and Faer Seth, 1981, Srivastava, 1985). However variations in the shape and orientation of deformed pebbles depends upon five factors: initial shape of the particle, initial axial orientation, strain-homogenieuy, the ductility contrast of the particles to the total particle/matrix system and errors in measurement. 27 SAMPLING METHOD; The samples were taken so that they describe repre sentative class of phenoclasts. Thirty five pebbles each were taken out carefully from two places and have been assigned location no.l and 2 respectively. Location no.l is close Adkalia while location no.2 is east of Adkalia village towards Lakapa. Tne measurements of X, Y and Z axis were taken from the extracted pebbles where X>Y>Z. {Annexure-1). SHAPE AMD ORIENTATION ANALYSIS OF PHENOCLASTS: The shape of the phenoclasts collected from the area was obtained by pebole axial ratio plots Y/X and z/Y on the ordinate and abscissa respectively (Zingg, 1935). Above plots were further superimposed by the sphericity curves (Krumbein, 1941) to compute the shape and sphericity relationship of phenoclasts. (Fig. lA and IB). Occurrence of phenoclasts of various shapes suggests that original shape of the phenoclasts might be different. In location no.l spherical and disc shaped pebbles are more while in location no.2 bladed and rod like pebbles are more (Fig.lA and IB ). More disc and spherical shaped pebbles in location no.l as compared to location no.2 might be due to lesser degree of deformation in locality no.l as compared to 28 RELflTior«/i:)iipor sPMerKjc/ry AND ZIHG,G ShAfei^^ic£f 29 ,.^AT;ONil^p"c^ SPH.RKlTy ANO^iN^.^ SHAPn.0/.^ C:J^V (fKaui 30 locality no.2 (Bhasker, A.A. and Fareeduddin,1981 ) . Variation in the degree of individual strata is common (Flinn, 1956). PHENOCLASTS POPULATION; To ascertain whether pebbles belong to same population or not X vs Z and f vs Z were plotted (Mukhopadhyay, 1973). Mukhopadhyay (1973), Roy and Ghosh (1979), Bhasker and Fareeduddin (1981) and Srivastava (1985) have demonstrated that pebbles of a single population show a good linear correlation for X vs Z and Y vs Z plots. On plotting above axial parameters good linear correlation was observed (Fig. 2A, 2B and 3A and 3B). According to Mukhopadhyay (1973) for a linear correlation model the value of 'X' should be zero when the value of 'Y' is zero. Therefore, according to Mukhopadhyay (1973) a linear correlation model Yi = p Xi + ei Where ei, is unobserved random variable causing deviation from perfect linear correlation. From the measured values of Xi and Yi the f3 values are calculated from the following equation: P = Xi :^i or Yi Zi £Yi2 ^Zi2 31 t^ ^'^ - • • I Ul '« N to —. O r^ csi -< '^ oD ^ U\ K\ ^ ^ 32 Vi\ < C^ N o4 t . ^5 t3- oo r^ '^ £>0 C4 ^ f.<^— r o N S >-. \t vn ^ CO rO cv^ K) t ^^ ^ CO >^ U) A-* 33 Where p is the line of best fit passing through the origin. Xi, Yi and Zi are the measurements of the individual pebble axes for which Xi>Yi>Zi. (Table 2 and 3). Goodness of linear correlation v/as also obtained from the equation: :^Xi Yi Y = / (iJXi^)(6Yi^) Where "V is the linear correlation model. For a perfect correlation its value should be unity. High ^ values obtained from such computation are indicative of good correlation between X vs Y and Y vs Z. DISCUSSIONS; The computed values on the basis of which plots of X vs Z abd Y vs Z shows a good linear correlation. (Fig. 2A, 2B, 3A and 3B). This good linear correlation of the peDDles indicate single population in the area (Mukhopadhyay, 1973 Roy and Ghosh, 1979 Bhasker and Fareeduddin, 1961 Srivastava, 1985). The value of y is also fairly nigh, so it can be concluded that the pebbles belong to a single population characterised by an axial ratio equal to p (Roy and Ghosh, 1979) (Table 2 and 3 ). 34 TABLE - 2 COMPUTED VALUES OF p AND Y OF PHENOCLASTS LOCATION NO.l S .No. Pxy "Yxy xy ^Y^ 1. 1, 296 1. 00 1.928 1. 00 2. 1, 358 1. 00 1.114 1. 00 3. 1 46 1. 00 1.612 1. 00 4. 1 15 1. 00 1.025 1. 00 5. 1 2 1. 00 1.38 1. 00 66 1. 00 1.724 1. 00 6. 1 111 7. 2, 31 0. 98 1. 0. 99 575 1. 00 1. 008 1. 00 &. 1 944 9. 1 428 0. 97 1. 0. 98 10. 1.5 1 00 1. 133 1. GO 11. 1.4 1 00 1. 25 1. 00 12. 1. 272 1 00 1. 32 1 00 13. 1. 428 1 .00 1. 166 1 00 14. 1. 44 0 .96 1. 162 0 99 15. 1. 437 1 .00 1. 061 1 00 16. 1. 25 1 .00 1. 714 1 .00 17. 1. 422 1 .00 1. 73 1 .00 18. 1. 638 1 .00 1. 894 1 .00 19. 1. 259 1 .00 1. 5 1 .00 20. 1. 33 0 .98 1, 363 0 .99 21. 1, 985 1 .00 1, 033 1 .01 22. 1, 666 1 .02 1, 142 1 .00 23. 1, 878 1 .00 1. 32 1 .00 24. 1 489 1 .00 1, 166 1 .00 25. 1, 439 1 .00 1, 2 1 .00 26. 1, 275 1 .00 1, 11 1 .00 27. 1, 685 1 .00 1, 35 1 .00 28. 1, 333 1 .00 1, 363 1 .00 29. 1, 235 1 .00 1, 533 1 .00 30. 1 451 0 .99 1 771 0 .98 31. 1 38 1 .00 1 315 1 .00 32. 1 315 1 .01 1 391 1 .00 33. 2 15 0 .99 1 ,625 1 .00 34. 3 71 1 .00 1 ,166 1 .00 35. 2 2 1 .00 1.25 1 .00 JSD TABLE - 3 p AND T VALUES FOR LOCATION NO.2 LOCATION NO.2 S . No, Pxy T - 1. 1. 973 1. 00 357 1. 00 2. i. 693 1. 00 265 1. 00 3. 1. 25 1. 00 277 1. 00 4. 1. 48 1. 00 562 1. 01 5. 1. 718 0. 99 515 0. 98 6. 025 1. 00 176 1. 00 7. 1 27 1. 00 2.107 1. 00 8. 2 11 1. 00 1.55 1. 00 9. 2 02 1. 00 1. 28 1. 00 10. 1 44 1. 00 1. 162 0. 99 11. 1 .431 1 00 2. 317 1. 00 12. 2 .009 1 00 1. 41 1. 00 13. 1 .437 1 00 2. 37 1 00 14. 2 .0 1 00 1. 23 1 00 15. 1 .807 0 99 1. 48 0 98 16. 1 .433 1 .01 1. 035 1 00 17. 1 .538 1 .00 1. 13 1 00 18. 1 .345 1 .00 1, 42 1 .00 19. 1 .38 0 .99 1 4 - 0 .99 20. 1 .65 1 .00 1 06 1 .01 21. 1 .51 1 .00 1 32 1 .00 22. 1.56 1 .00 1 61 1 .00 23. 1.57 1 .00 2 06 1 .00 24. 1, 11 1 .00 1 ,24 1 .00 25, 1, 59 1 .00 1 ,24 1 .00 26, 1, 76 1 .00 1.52 1 .00 27, 1 69 1 .00 1.26 1 .00 28, 1 27 1 .00 2.1 1 .00 29, 1 16 0 .98 1, 34 0 .99 30, 1 69 0 .99 1, 35 1 .00 31, 1 98 1 .00 1, 41 1 .00 32, 1 66 1 .02 1 73 0 .99 33 1 58 1 .00 1 24 1 .00 34, 1 23 1 .00 1 8 1 .00 35 1.16 1.00 1.33 1 .00 36 The shape of the ellipsoid is given by the expression: ^ - 1 K = ^ - 1 K values had been determined which shows considerable variations. Variations in K values are due to variation in intensity of deformation, initial shape and orientation of pebbles. The axial ratios of —X were also plotted against the ratios of Y/z {Fig.4A and 4B Pamsay, 1967) . STRAIN ANALYSIS: Geometric effects during the deformational processes were studied to find out the nature of deformation to which supracrustal rocks in the study area was subjected. In order to determine strain, nine basic parameters are required. Three of them are related to distortinal changes while other six are related to orientation and relation of the particles during deformation. Above mentioned nine parameters are to be determined to define the finite strain geometry (Ramsay, 1967; Ramsay and Graham 1970 Ramsay and Wood, 1973). 37 But in area where known markers are inadequate, the study ot nine parameters for finite strain determination is impossible. To determine deformation analysis the graphical metnod for strain analysis of the phenoclast was adopted. DEFORMATION FIELD: The phenoclast population was of elliptical particles as indicated by X vs Z and Y vs Z plots (Fig. 2A, 2B, 3A, 3B). It was not possible to measure the three principal component of elongation related to distortional changes namely ^1, ^2 and €3 absolutely. Shape change can be determined by deformational plots of the phenoclast population in which the ratios of principal semi-axes lengths were plotted as abscissa and ordinate (Flinn 1962). The natural logarithm of the ratio of principal Semiaxis were plotted. In [ (1 + el)/{l + e2) ] as ordinate and In [{l+e2)] / (l+e3)] as abscissa (Ramsay, 1964 >Dunnet 1969; Helm and Siddans, 1971; Ramsay and Wood, 1973), for determination of strain parameter. These plots, however, are not adequate to serve as replacement where nine parameters are necessary for strain measurements (Ramsay, 1967 Ramsay and Graham, 1970 Ramsay and Wood, 1973) suggested more easy method of two-dimensional graphic representation of strain where deformation plot is plotted as the difference between the principal logarithms strain 38 1^ o o u> —1— -«— t «— Q Va o ^ o \n *0 o AA M >> ^ -J < In < O CD -D '-ij 'j> CO Osl ^ >> <5 O ^ 3 ti^ o O ^N >1 vo Vx 39 €.2 - 63 ana £l - £2 along abscissa and ordinate respec tively (Fig. 5A and 5B). The logarithmic strain is given by the equation: e = In (I + e) The geometry of the deformation ellipsoid is expressed in terms of K, where K is the ratio between the principal natural logarithms strain. ^1 - ^2 K = ^2 - ^3 The line of unit slope drawn from origin divides field into prolate and oblate ellipsoid. The deformational plots lying along the abscissa represent flattening ellipsoid for which ^2 is positive. The plots towards ordinate represents constriction field for which €2 is negative. The ellipsoid which fall on the line of unit slope (K=l) represents plain strain for which €2=0. The principal natural logarithms strain e , £ and €^ and parameter K were plotted (Fig.SA and 5Bj. The plots indicate tnat both in location no.l and 2 pebbles lying in constrictional fields are more as compared to flattening 40 n\ ii i4K4co •8 i^K>yO ' •&• 4} •2i ''^ «— •1 •2 •3 -4 s -6 7 ^ 8 /•o e,-e2 Vf f"a-€j P^OT^ 41 10^ •8 i<;<4-oo l>/?>0 V4J •4- • 2 •i -2 -3 -4- •$ -C 7 -9 9 1-0 t; 1- 63 ^oc- 2 6-62 V5 ^2'^J PLOTg 42 vF -J o a: p --1 1 1^ 00 C9 T >> T -^ o T i J VJ • Ul Q. -4 k a. 11 '^ < h T* 5 z 1 v5- U T o /^, !>> 3L '^^ ^^ ^ /\ ^co V v5^ E 1 T = -^ • a: h v5 ^ JO §3 o . h u. vi 5. ^ 4 ^ ^ o X Z. ^7o~ON'3m3^Jf J 43 field. In location no.l about 51.5% lie in constrictional field, 45.6% lie in flattening field while about 2.6% lie in plain strain field. In location no.2 60% lie in constrictional field {K>1), 37.4% in flattening field while about 2.6% lie in plain strain field. (Fig.5A, 5B, 6A and _ 6B). However, these inferences are based on assumption of constant volume deformation (Ramsay and Wood, 1973). FINITE STRAIN IN THREE-DIMENSION; To determine finite strain in three-dimension finite strain geometry of the phenoclasts were studied to determine principal natural strain components (€-1, €-, and €•,), natural octahedral unit shear Cfo) and Lode's ratio ( *\) )• These parameters were computed and plotted on the polar graph (Nadai, 1963 Hossack, 1968 Gay, 1969 Mukhopadhyay, 1973; Roy and Ghosh, 1979 Srivastava 1985). Principal natural strain £ £ and £^ were determined by formula € = log(l+e). For finite strain it is easier to express in terms of natural strain (Ramsay,1967 Mukhopadhyay,1973) . From the axial ratio of the strain ellipsoid the deviatoric components of strain parameters were computed. Tne radius (R) a sphere having the same volume as the ellipsoid is calculated. The deviatoric components of principal natural elongation are given by /Al - ^/R'/A2 = Y/R;/:5\l = Z/R (X > Y >Z 44. The deviatoric components of principal natural strain is expressed by formula: (e^) = loge X/:.R i^^) = loge Y/R (6-,) = loge Z/R (Annexure - 2) The magnitude of strain was determined following Nadai's (1963) natural octahedral unit shear (To) 2 Finite strain is given by ? to / (ei)2 + (€2)^ + (^3) (Nadai, 1973 Hossack, 1968; Makhopadhyay, 1973). For determination of finite strain, Lode's parameter (^) ) is determined (Hossack 1968 ; Gay 1969; Mukhopadhyay 1973 and Srivast£va 1935). 45 TABLE - 4 RESULTS OF Vo, £5 and S) LOCATION NO.l S.No. To ^ 1. .761 0 659 0.435 2. .347 300 -0.478 3. 0.696 0 602 .120 4. 0.148 0 128 -0.682 5. 0.417 0 361 0. 282 6. 0.849 0 735 0. 035 7. 0.296 0 256 -0. 470 8. 0.746 0 646 0. 015 9. 0.917 0 795 0. 357 10. 0.484 0 420 -0. 528 11. 0.453 0 392 -0. 2 12. 0.418 0 362 0. 069 13. 0.425 0 368 -0. 382 14. 0.427 0 369 -0. 413 15. 0.741 0 641 0. 205 16. 0.632 0 ,547 0 413 17. 0.731 0.633 0 216 18, 0.917 0.794 0 127 19. 0.518 448 0 2 76 20, 0.506 438 0 .033 21, 0.548 475 -0 .586 22, 0.548 475 -0 .583 23, 0.751 65 -0 .386 24, 0.434 376 -0 .412 25, 0.474 410 -0 .33 26, 0.287 249 0 .126 27, 0.671 581 -0 .269 28, 0.481 417 0 .036 29, 0.539 466 0 .297 30 0.765 663 0 .207 31, 0.481 417 -0 .077 32 0.485 420 0 .042 33, 1.02 883 -0 .223 34, 1.301 127 -0 .789 35 0.858 743 -0 .558 46 TABLE - 5 RESULTS OF Y© / €s andS) LOCATION NO.2 S.No. To ^ i. 0 ,814 0.705 .378 2. 0 ,629 0.545 .382 3. ,389 .337 .099 4. ,677 .586 .064 5. .772 .668 .133 6. .744 .644 .623 7. .83 .718 .512 8. .968 .838 .259 9. .798 .691 .478 10, .427 .369 .413 11. .993 .86 .4 12. .847 .773 .33 13. .016 .88 .407 14. .766 .663 ,53 15. .802 .695 ,197 16. .351 .304 ,826 17. .467 .404 .557 18. .522 .452 ,092 19. .53 .459 ,02 20, .707 ,0038 .816 .486 .19 21, .561 .646 ,016 22, .746 .83 ,226 23. .959 ,37 24, .488 .564 .485 •,356 25, .561 26 .692 •.143 .8 .545 •.382 27, .629 28 .623 .512 .72 .312 .297 29, .36 30 .581 .269 .671 .733 -.33 31 .847 32 .737 .037 .85 .485 33 .561 -.356 34 .575 .664 ,312 ,356 35 . 36 .2 97 47 LOC- i 48 FIG.-7^ UDc- 2. 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Springer-verlag, Newyork. 60 DESCRIPTION OF PLATES PLATE - 1 Figure 1 Conglomeratic schist containing pebbles of quartzite and marble. Stratification is inclined to pebble and pebble size varies. Figure 2 Quartzitic rock from Quartzite-Marble unit. PLATE - 2 Figure 3 Conglomeratic schist showing orientation of chlorite and deformation of quartz grain in plain of strain ellipsoid. Crossed nicols x 6.3 Figure 4 Quartzite having first type of quartz having sutured contact and elongated shape. Crossed nicols x 6.3 PLATE 3 Figure 5 Quartzite showing quartz having equant in shape with polygonal outline. Crossed nicols x 6.3 Figure 6 Quartzite showing quartz occurring as large porphyroblasts. It exhibits triple point junction and linear contact. Crossed nicols x 6.3 61 PLATE - 4 Figure 7 Calcareous quartzite exhibiting presence of calcite and dolomite. There is embayment of calcite and dolomite within quartz grain. Plane polarised light. Figure 8 Calcareous quartzite exhibiting presence of dolomite and calcite. Twin-lamellae can be seen. Crossed nicols. r . %. M^Ji. fl<^-l fl^ Fr±i Fl6,-f fi(^-5' r/^6 f/4-? Fi^-^ ^ ? ANNEXURE - 1 LOCATION NO.l MEASUREMENTS OF LENGTH OF PEBBLES (CMS.) S.No. X Y u 1. 10.5 8.1- 4 ,2 2. 5.3 3.9 'i, „ 5 3. 7.3 5 .'" ..'- 4. 4.6 4 3.'^ 5. 6 5 J . d 6. 8.3 5 1 Ci 7. 4.3 3.3 J 8. 6.3 4 '2_ . ^ 9. 5 3.5 1.3 10. 5.1 3.4 11. 6.3 4.5 3.'1 12. 4.2 3.3 2. -5 13, 7 4.9 ^.2 14. 7.2 5 .1 15. 11.2 7.8 l.D 16. 3 2.4 i.4 17. 6.4 4.5 2.6 18. 5.9 3.6 1.9 19. 3.4 2.7 i.8 20. 4 3 ? . I 21. 5.9- 3.1 '1 22. 4 2.4 2.1 23, 6.2 3.3 2 .5 24. 7.3 4.9 4.2 25. 6.9 4.8 \ 26. 5.1 4 3.6 27. 9.1 5.4 4 28. 6 4.5 3 . 3 29. 5.8 4.6 3 30. 9 6.2 3.5 31. 6.9 5 3.8 32. 4.2 3.2 2 . 3 33. 14 6.5 4 34. 13 3.5 3 35. 5.5 2.5 2 63 ANNEXURE - 1 LOCATION NO.2 MEASUREMENTS OF LENGTHS OF PEBBLES (CMS.) S.No, Y 1. 7. 5 3. 8 2. 2. 10. 5 6. 2 4. 9 3. 7, 5 6 4 .6 4. 7, 4 5 3 .2 5. 12, 2 7. 1 4. 7 6. 8, 1 4 3. 4 7. 7, 5 5. 9 2. 8 8. 9 ,5 4. 5 2. 9 9. 8.3 4. 1 3, 2 4. 3 10. 7.2 5 13.6 9. 5 4. 1 11. 14.3 7, 2 5. 1 12. 9.2 6, 4 2. 7 13. 12 5 14. 6 19 9 5. 2 3, 5 15. 4 2, 9 16. 3 4 2, 6 2 ,3 17. 6 3 ,3 18, 4 .7 19. 5 4 .2 3 20. 6 4 2 .4 21. 6 4 .1 3 ,1 22. 5 3 .7 2 .3 23, 5 3 .3 1 ,6 24. 10 6 .7 5 .4 25. 8 5 .6 4 .5 26. 5 2 .9 1 .9 27. 10 6 .2 4 .9 28, 7 5 .9 2 .8 29, 2 2 .4 1 .8 30, 9 5 .4 4 31 14 7 .2 5 .1 32, 8 5 2 .89 33. 8 5 .6 4 .5 34, 4 3 .8 2 .1 35, 2 2 .4 i 64 ANNEXURE - II DEVIATORIC COMPONENTS OF PRINCIPAL NATURAL STRAIN LOCATION NO.l S.No 1. .39 .132 .524 2. .242 -.064 .172 3. .411 .033 .449 4. .102 -.036 .062 5. .231 .048 .279 6. .519 .012 .532 7. .208 -.056 .151 8. .46 .0052 .464 9. .459 .102 .653 10. .312 -0 093 .218 11. .298 037 .26 12, .253 012 .265 13. .289 067 .226 14. .293 071 .222 15, .424 062 .487 16, .328 105 .433 17, .417 065 .482 18 .542 048 .59 19 .288 0583 .347 20 .295 0076 .3 21 .051 459 .592 22 .385 125 .259 23 .512 117 .395 24 .289 081 .235 25 .302 06 .242 26 .197 045 .151 27 .448 073 .373 28 .295 0, 0075 .302 29 .296 065 .362 30 .439 066 -.502 31 .306 015 -.29 32 .291 0034 .31 33 .673 093 -.579 34 .926 ,385 .539 188 35 .6 .411 65 ANNEXURE - II DEVIATORIC COMPONENTS OF PRINCIPAL NATURAL STRAIN LOCATION NO.2 S.No ^1 ^2 1. + 0, 555 0.124 -.43 2 . 0 429 0.097 -0.332 3. 0, 231 0.014 -.251 4. 410 .018 - .428 5. 498 -.042 -.455 6. 524 - .18 -.343 7. 408 .168 -.577 8. 644 - .102 - .541 9. 552 -.152 -.40-0 10. ,293 - .071 -.222 il. ,519 .16 -.67. 12. ,572 - .113 -.458 13. ,529 .166 -.696 14. ,534 - .16 -.373 15. ,526 -.065 -.461 16. ,251 - .108 -.142 17. ,328 -.102 -.224 18. ,313 .02 - .333 19. .327 .0047 -.331 20. .504 .0035 -.507 21. ,368 -.044 -.324 22. .458 .0036 -.466 23. .544 .089 -.633 24. .384 -.084 -.299 25. .381 -.081 -.30 .517 26. - .047 -.470 27. .42 9 - .097 -.332 .408 28. .168 .199 -.576 29. .044 .448 -.242 30. -.073 .572 - .373 31. -.113 .52 -.458 32. .013 .381 - .534 35. -.081 .339 -.30 34. -.212 .199 -.466 35. .044 -.242