Mineralogy and Geochemistry of Felsic Magmatic Rocks in

the Kameng District, Western Arunachal Himalaya

Thesis submitted to

Department of Geology Centre of Advanced Study in Geology

Kumaun University, Nainital

for

the requirement of degree of

Doctor of Philosophy in Geology

MANJARI PATHAK Department of Geology

Centre of Advanced Study in Geology Kumaun University, Nainital

Nainital 2012

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To my teachers….

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Date: 04/10/12

CERTIFICATE

Certified that Manjari Pathak has carried out the research work for the award of

Doctor of Philosophy on the topic "Mineralogy and Geochemistry of Felsic Magmatic

Rocks in the Kameng District, Western Arunachal Himalaya", under my supervision

in the Department of Geology, Faculty of Science, Kumaun University, Nainital,

Uttrakhand.

The thesis embodies the original work based on field and laboratory

investigations carried out by her. She has pursued a course of research for the period

required under the ordinance laid down by Kumaun University for the degree of Doctor

of Philosophy. She has also put the attendance in the Department of Geology, during the

research period required under ordinance.

Thus, Manjari Pathak is entitled to submit thesis for the Ph.D. Degree in

Geology of the Kumaun University.

(Santosh Kumar)

Professor and Supervisor

Santosh Kumar, Professor Department of Geology Centre of Advanced study in Geology Kumaun University, Nainital-263 002 Uttarakhand, India

Phones: (O) : +91-5942-239596, 235114 (R) : +91-5942-239953 (M) : +91-9411197714

(Fax) : +91-5942-235576 E-mail: skyadavan@yahoo.com

skyadavan@gmail.com

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CONTENTS

Page No.

Acknowledgements i-ii

List of Figures iii-xii

List of Tables xiii-ivx

Chapter 1: Introduction 1-10

1.1 Introduction 1

1.2 Granite Types 3

1.3 Spatial and Temporal Distribution and Magmeto

-tectonothermal Evolution of Granites in India 4

1.4 Researches on western Arunachal Himalaya 7

1.5 Aim and Scope of Present Study 9

Chapter 2: Methodology and Instrumental Techniques 10-19

2.1 Introduction 10

2.2 Field Techniques 10

2.3 Method of Sample Preparation 11

2.3.1 Thin section preparation 11

2.3.2 Fine powdering 12

2.3.3 Loss on ignition (LOI) determination 12

2.4 Analytical Methods 13

2.4.1 Microscopic methods and modal mineral analysis 13

2.4.2 Electron Probe Micro Analysis (EPMA) 13

2.4.3 X-ray Fluorescence Spectrometry (XRF) 15

2.4.4 Inductively Coupled Plasma Mass Spectrometery

(ICPMS) 15

2.4.5 Laser Ablation – Multi Collector – Induced

Coupled Plasma Mass Spectrometer

(LA-MC-ICPMS) 17

2.4.6 Software and rockware 18

Chapter 3: Geology, Field Relation and Magnetic Susceptibility

Mapping 20-54

3.1 Location and Accessibility of the Area 20

3.2 Physiography 21

3.2.1 Himalayan Range

3.2.2 Trans – Himalayan Range

3.2.3 Naga – Patkoi Range

3.2.4 Brahmaputra Plain

3.3 Drainage 23

3.4 People 24

3.5 Climate, Flora and Fauna 24

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3.6 Regional Geology 25

3.6.1 Geology and Tectonics of Arunachal Pradesh 25

3.6.2 Geology and Field relationship in the study area 28

3.7 Granitoids in the Western Arunachal Himalaya 30

3.7.1 Se La Group 30

3.7.2 Bomdila Group 34

3.7.3 Salari Group 46

3.8 Sample and Location 49

3.9 Magnetic Susceptibility and Granite Series 50

Chapter 4 Petrography, Modal Mineralogy and IUGS Nomenclature 55-75

4.1 Petrography 55

4.2 Ms-Bt Granite Gneiss (GGn) 55

4.2.1 Megascopic features

4.2.2 Microscopic features

4.3 Hbl-Bt Granite (GGn) 63

4.3.1 Megascopic features

4.3.2 Microscopic features

4.4 Minerals’ Paragenesis of Granitoids 72

4.5 Modal Mineralogy and IUGS Nomenclature 74

4.5.1 Ms-Bt granite gneiss (GGn)

4.5.2 Hbl-Bt granite (HBG)

Chapter 5 Mineral Chemistry and Intensive Variables

5.1 Introduction 76

5.2 Feldspar 76

5.2.1 Plagioclase

5.2.2 K-feldspar

5.3 Amphibole 82

5.4 Mica 83

5.4.1 Biotite 85

5.4.1.1 Classification of biotite

5.4.2 Muscovite 89

5.4.2.1 Classification of muscovite

5.5 Tourmaline 93

5.5.1 Classification of tourmaline

5.6 Intensive Variables 103

5.6.1 Al-in-hornblende barometer

5.6.2 Hornblende-plagioclase thermometer

5.6.3 Two-feldspar thermometer

5.6.4 Temperature (T) and oxygen fugacity (fO2)

Chapter 6 Geochemistry and Zircon Chronology 108-136

6.1 Introduction 109

6.2 Geochemical Classification 109

6.3 Major Element Geochemistry 112

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6.3.1 Ms-Bt Granite Gneiss (GGn) 112

6.3.1.1 Major element characteristics

6.3.1.2 Major element behaviour

6.3.1.3 Normative composition

6.3.2 Hbl-Bt Granite (HBG) 119

6.3.2.1 Major element characteristics

6.3.2.2 Major element behaviour

6.3.2.3 Normative composition

6.4 Trace Elements Geochemistry 120

6.4.1 Ms-Bt Granite Gneiss (GGn) 121

6.4.1.1 Trace elements characteristics

6.4.1.2 Trace elements behaviour

6.4.2 Hbl-Bt Granite (GGn) 122

6.4.2.1 Trace elements characteristics

6.4.2.2 Trace elements behaviour

6.5 Mantle-Normalized Spidergrams 125

6.6 Rare Earth Elements (REE) Geochemistry 126

6.6.1 Ms-Bt Granite Gneiss (GGn)

6.6.2 Hbl-BT Granite (HBG)

6.7 Tectonic Environments 128

6.8 Zircon U-Pb-Lu-Hf Isotopes 131

6.8.1 Ms-Bt Granite Gneiss (GGn)

6.8.2 Hbl-Bt Granite (HBG)

Chapter 7 Discussion 125-162

7.1 Introduction 126

7.2 Field Petrography 126

7.2.1 Textural variation and their significance 126

7.2.1.1 Ms-Bt Granite Gneiss (GGn)

7.2.1.2 Hbl-Bt Granite (HBG)

7.2.2 Granite Series Evaluation 129

7.2.2.1 Magenetic susceptibility and granite series

7.2.2.2 Modal compositions, nomenclature and inferred igneous

series

7.3 Microtextural variations and genetic significance 133

7.4 Geochemical Evolution of Mineral Phases 136

7.4.1 Feldspar composition

7.4.2 Amphibole composition

7.4.3 Biotite composition

7.4.3.1 Nature of felsic magmas and operative elemental

substitution

7.4.3.2 Temperature and oxybarometer of HBG melt

7.4.3.3 Tectonic implication

7.4.4 Muscovite composition

7.4.4.1 Substitution relations

7.4.5 Tourmaline compositions and magma environment

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7.4.5.1 Site-occupancy and substitution relations

7.5 Physical conditions of granite emplacements 146

7.5.1 GGn emplacement based on whole-rock norm

7.5.2 Al-in-hornblende barometer for HBG 147

7.6 Bulk Geochemistry 148

7.6.1 Nature of felsic melts 148

7.6.2 Geochemical variations: key to the magmatic

Processes 148

7.6.3 Elemental variations and their genetic interpretations 149

7.6.3.1 Major and trace elements

7.6.3.2 Trace and rare earth elements pattern

7.6.4 Modelling the Fractional Differentiation 152

7.6.4.1 Ms-Bt Granite Gneiss (GGn)

7.6.4.2 Hbl-Bt Granite (HBG)

7.6.5 Ambiguous nature of HBG melt 155

Classical arc-type vs high-silica adakite(?) vs

TTg-derived melt

7.6.6 A viable tectonic model and mechanism of felsic

melt generation 160

7.6.7 Zircon U-Pb-Lu-Hf isotopes: as age of

emplacement and petrogenetic tracer 160

Chapter 8 Conclusions 163-166

References 167-191

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AcknowledgementsAcknowledgementsAcknowledgementsAcknowledgements

I am especially grateful to Professor Santosh Kumar, technically my supervisor but truly my

inspiration and ‘mentor’ who introduced me to the subject, believed in me early, and with whom I

always found myself at receiving end. I am obliged to him for sharing his valuable time, vast

experience and in-depth knowledge to me. I thank him for all the support, positive attitude,

encouraging and enthusiastic research-environment. The present research work was supported under a

DST-funded project granted to Professor Santosh Kumar on NE-HIMPROBE

(ESS/16/242/2005/Kameng/04).

My sincere thanks and regards to Professor C. C. Pant, Head of the Department, for

providing the facilities available in the department and UGC-SAP JRF fellowship for the period 01-

04-2009 to 30-09-2011. The helps and support rendered by all the faculty members of the department

are gratefully acknowledged.

Special thank to Mr. U. C. Upadhyay, for his untiring efforts in preparing excellent thin-

sections, and in turn helping me to put the base of the present research work. Shri K. D. Mathela,

Shri, V. N. Ghoshal, C. S. Dhaila and all the staff of the department are acknowledged for the helps

and office assistance.

The helps provided during analytical work by Dr. N.K. Saini, Dr. D R Rao, Dr. Rajesh

Sharma, Mr. Shekhar, Mr. Thapaliyal and Mr. Dinesh at WIHG Dehra Dun; Dr. Sandeep Singh at

IIT, Roorkee; and Dr. V. Balaram, Dr. M. Satyanarayanan, Dr. T. Yellapa, and Miss Prachiti

Kanakdande at NGRI Hyderabad, are gratefully acknowledged. I would like to thank Institute of

Geology and Geophysics, Chinese Academy of Sciences, Beijing, P. R. China, for providing an

opportunity to Professor Santosh Kumar to work with LA-MC-ICPMS instrument during isotopic

analysis.

Mr. Mayank Joshi and Mr. Prabhin Sukumaran, my ‘link’ to assess science direct and

libraries, are highly acknowledged who helped me in a great way by providing valuable and essential

scientific literature, whenever I requested. Thanks to all the researchers and scientist who responded

promptly to my requests and helped me by sending requested and many more relevant research papers.

Humble and wholeheartedly thanks to my respected parents, who invested so much to me,

loved and cared almost to the point of self-destruction and at every step of the way, they were with me

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even though they were physically thousands of miles away. It is an honor to be their daughter and to

carry their name. I feel an overwhelming sense of gratitude towards Himanshu, my elder brother,

Girish, my husband and my parents-in-laws who never let me turn around and helped me in calm and

indirect way to make my ambition true. Their imperial support is highly acknowledged. Warm thanks

to my brother, sisters and relatives for their support and encouragements.

I feel obligated to mention the names of a few friends, whose support meant beyond what

they realize. I thank Dr. Brajesh Singh, for all his brotherly support in field and lab, Ritu, for being

present always with her readymade solutions to any of my problems, and for her positive energy

around me, Sita, for being caring and supportive friend and for helps rendered during final correction

and compilation of thesis. Seniors Manju, Prabha, Mouli, Nidhi, Archana, Abhishek and Peru friends

Surdas, Rogi, Aarti Vikas, Shefali, Ajay and colleagues Neha, Manisha, Hunnsa, Chitra, Manohar,

Deepak, Jay, Alpana, Sheetal, Dipti, Lalit, Gunjan, Tanuja and finally Prakash Da for their best

wishes and providing a welcoming environment at department.

NAINITAL (Manjari Pathak)

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List of Figures

Figure 1.1 The granite series according to H. H. Read (1956) (after Pitcher, 1993). 2 Figure 3.1 Geological map of Arunachal Himalaya showing the various corridors along

major rivers of the region (after Jain, 2006). These corridors were studied by various groups under DST-DCS programme ‘NE-Himprobe’. Present study is an integral part of the study on ‘Kameng Corridor’. ………………………………20

Figure 3.2 Drainage map of the western Arunachal Himalaya showing four orders of

streams with dendritic pattern (Extracted from ASTER satellite data using GIS based software global mapper 6)……………………………………………… 22

Figure 3.3 Geological map of the Himalayan mountain belt (after Valdiya, 2010) showing

the distribution of Higher and Lesser Himalayan crystalline sheet and metadesiments spreading across the strike of Himalaya from west to east.. ……25

Figure 3.4 Simplified geological map of the west Kameng district, western Arunachal

Himalaya (after Srinivasan, 2001) showing the granitoids of Bomdila and Salari Groups. ………………………………………………………………………….27

Figure 3.5 Hornblende-biotite granite gneiss (HBGGn) near Sapper, north of the Main

Central Thrust, Se La Group, Higher Himalaya (a) migmatite-like nature of HBGGn (b) sheared nature of HBGGn…………………………………………..30

Figure 3.6 Granite gneiss from Tawang region, Se La Group, Higher Himalaya (a) figure

showing the gneissic to migmatitic nature of TGN with well developed quartzofeldspathic augens, shearing is also present, (b) migmatized TGN with ptygmatically folded leucocratic neosome, (c) extensional boudinage structure developed in TGN………………………………………………………………..32

Figure 3.7 Tourmaline bearing Leucogranite TLG in Se La Group of Higher Himalaya (a)

dykes of leucogranite intruding the metasediments of Se La Group, (b) colse view of two-mica leucogranite and tourmaline nodules bearing pagmatite. Note the magmatic flowage structure in granite near the pegmatite-granite contact, (c) massive outcrop of leucogranite in contact with the biotite-rich metapelite, (d) sill-like massive intrusion of leucogranite into the metapelites (base of the photograph is equal to 9 m)……………………………………………………………………33

Figure 3.8 field photographs of GGn showing (a) primary undeformed nature of GGn

where randomly oriented tabular phenocrysts of feldspar are characterized by sharp and straight crystal boundaries, (b) GGn characterized by subhedral to euhedral

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phenocrystas of K-feldspar of varying sizes, giving porphyritic texture, however the groundmass is relatively fine grained and foliated………………………………..36

Figure 3.9 (a) Deformed GGn characterized by foliations well defined by the alignment of

micaceous minerals. The coarse phanocrysts are of elliptical shaped giving augen-like structure. Note the melanocratic mafic segregate in GGn parallel to the foliations, in the left side of the picture and (b) GGn is characterized by abundant feldspar phenocrysts of varying shape and sizes………………………………….37

Figure 3.10 (a) Porphyritic GGn with tourmaline clusters, where tourmaline crystal are

characterized by dark colour and nodular form, and (b) highly deformed GGn showing structural fabrics (S-C fabric) pertaining to ductile deformation………..38

Figure 3.11(a) Streaky gneiss, a variety of GGn characterized by banded nature, where

quartzofeldspathic material has flowed giving rise to mylonitic structure, (b) intense grain size reduction in GGn due to pulverization and strain softening in ductile environment resulting in typical mylonite………………………………………...39

Figure 3.12 (a) Undigested metasedimentary or pelitic xenolith hosted in GGn near Tenga,

which is showing sharp contact with its host and aligned parallel to major foliation, (b) sharp contact between metasedimentary and GGn where quartzofeldspathic vein (1.5cm) is remarking the contact near Nine Mile locality (see text for description)................................................................................................................40

Figure 3.13 (a) Cold intrusive showing sharp contact between GGn and mylonitized

metasediments of Chilliphum Formation of Bomdila Group near Tenga, (b) intrusion of feldspar phenocryst bearing GGn melt into the metasediments of Bomdila Group along major foliation planes or bedding(?) friezed insitu and showing gradational intrusive contact…………………………………………….41

Figure 3.14 (a) Leucocratic GGn present at the northeastern part of Bomdila near Kiriphum

village, characterized by multi stage of deformation evident by its intense foliated and crenulated nature, it is in association with (b) leucocratic GGn representing the evolved fraction of GGn with less degree of deformation, which is foliated, where foliation is defined by the alignment of mica……………………………………..42

Figure 3.15 (a) Leucocratic variant of GGn presnt on Dirang-Sessa section, less deformed

to undeformed and medium grained in nature representing the evolved fraction of GGn melt, (b) sharp contact of leucocratic GGn with quart-arenite of Bomdila Group south of the Zero point on Sessa-Dirang road. The country rock is highly silicified, hard and compact (base of the photograph is equal to 15 m)…………...43

Figure 3.16 (a & b) Quartzofeldspathic pegmatites of varying shape, sizes and thickness

intruding the metasediments of Bomdila Group very close to the intrusive contact between metasediments and GGn. These pegmatites are tourmaline bearing and are

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representing the late magmatic activity of GGn. Base of the photograph is 12 m in (a) and 9 m in (b).......................................................................................................44

Figure 3.17 (a) Quartzo-feldspathic veins and pegmatite representing the late magamtic

event of GGn found intruding the GGn itself, and (b) a thick quartzofeldspathic pegmatite intruding GGn near Tenga (on Bomdila-Dirang road) hosting abundant of tourmaline nodules varying in size from 2 mm to 5 mm……………………….45

Figure 3.18 Tourmaline in radiating and patchy form into the quartz-arenite of the Bomdila

Group (country rock) in the contact aureole of GGn intrusion at bifurcation of Rupa - Dirang road……………………………………………………………………...46

Figure 3.19 Google image of the Salari village used to demarcate the field boundaries of

intrusive HBG with metasediments. HBG is exposed only as a thin lense or small intrusive body between the metasediments of Bomdila Group. Limit of GGn body is also shown……………………………………………………………………..46

Figure 3.20 Intrusive nature of HBG shown by (a) sharp intrusive contact between HBG

and overlying metasediments where HBG exhibits relatively leucocratic nature near intrusive contact, base of the photograph is equal to 25m, (b and c) abundant and irregular shaped country rock (shale) xenoliths of various sizes are engulfed in HBG demonstrating the intrusive shallow-level nature of HBG. Note the leucocratic nature of HBG near intrusive contact in (a) and (c)…………………..48

Figure 3.21 (a and b) Rounded to elliptical mafic magmatic microgranular enclaves

containing felsic phenocrysts hosted in HBG, (c) Hard and compact nature of massive mesocratic non foliated and fresh nature of HBG……………………….49

Figure 3.22 Google image of the Kameng corridor of western Arunachal Himalya with the

GPS locations from where samples and geological field data have been collected. The yellow line is the international boundary between India and Bhutan………...50

Figure 3.23 The geological map of the study area showing the average magnetic

susceptibility of the granitoids at various studied locations………………………50 Figure 3.24 Magnetic susceptibility variations of felsic magmatic lithounits of western

Arunachal Himalaya along (a) Sessa-Bomdila-Tawang, and (b) Ninemile-Salari-Nafra transects. Symbols are (○) GGn, (∆) HBG, (+) TLG, (□) HBGGn, and (♦)TGN)…………………………………………………………………………..52

Figure 4.1 Photomicrograph of GGn showing (a) inequigranular porphyritic texture, where

subhedral plagioclase is present as phenocryst with mineral inclusions, albitic twinning, and normal zoning, (b) myrmekitic intergrowth at the interface of albitic plagioclase and K-feldspar and (c) Megacryst of K-feldspar enveloped by mica flakes, showing augen-like texture. The right upper corner of photomicrograph depicts asymmetric dynamic recrystallization of quartz and K-feldspar. K-feldspar

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exhibits intense myrmekites , where two rows of myrmekitic lobs have grown facing each other………………………………………………………………….57

Figure 4.2 The photomicrograph of GGn showing (a) microperthitic texture in anhedral K-

feldspar, which is characterized by Carlsbad twinning, while the subhedral plagioclase displays albitic twinning and contains quartz and mica inclusions. Quartz is recrystallized with sharp grain contacts (b) flame and string perthite in K-feldspar phenocryst which is subhedral and has inclusions of quartz and biotite. Biotite is present as mafic aggregates, associated with muscovite flakes, and (c) subhedral platy flakes of biotite and muscovite, together defining the foliation.…58

Figure 4.3 (a) Fractured anhedral tourmaline crystals in GGn showing different pleochroic

colour sheds, (b) subhedral to anhedral, medium to coarse grains of zoned greenish-blue coloured tourmaline crystals in GGn. Fractured parts of tourmalines are filled with quartz………………………………………………………………………..60

Figure 4.4 Photomicrographs (a, b, c) showing zircons as inclusions mostly hosted in the

biotites of GGn. These zircon crystals are prismatic, euhedral, colourless, and characterized by very high relief. One set of cleavages and irregular fractures are some of the others diagnostic features of zircon. Zircon also possesses roundness.61

Figure 4.5 (a) Porphyritic texture in HBG with tabular coarse plagioclase which is highly

sericitized in core with albitic twinning. Biotite is present as interstitial anhedral phase with magnetite inclusions, (b) equigranular texture in HBG with anhedral plagioclases enclosing acicular apatite and fine quartz. Biotite occupies the interstitial phase along with quartz, (c) Microperthite and medium to coarse grain of sericitized subhedral plagioclases showing complex twinning (albitic and Carlsbad), and are also present as inclusion in K-feldspar…………………………………..64

Figure 4.6 Microphotographs (a) showing Carlsbad and cross-hatched (complex) twinning

in microcline, which has inclusions of quartz. Plagioclase is relatively coarse grained, highly sericitized. (b) microperthite in HBG with veins, flames and strings of exsolved albite in K-feldspar. It contains inclusions of sericitized plagioclases. ……………………………………………………………………………………67

Figure 4.7 Photomicrographs (a, b, c) showing porphyritic texture with hornblende and

plagioclase phenocrysts. Hornblendes are anhedral to pseudohexagonal and plagioclases are highly serisitized Hornblende is also biotitized………………….68

Figure 4.8 (a) Clinopyroxene exhibits resorbed texture in the core of the hornblende, and

biotitization of hornblende along the cleavages and grain boundaries is common, (b) hornblende and biotite form mafic clots in HBG, (c) euhedral titanite coexisting with biotitized amphibole equilibrated in an felsic matrix, (d) coarse grained poikilitic biotite in HBG with frequent exsolved inclusions of titanite along the cleavages. Note the bent nature of cleavages in biotite, (e) coarse biotite phenocryst with bent cleavages, associated with plagioclase and hornblende, and (d) deformed

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nature of biotite with bent cleavages, and cholritzation of biotite can be noticed along the grain boundary. Biotite is associated with plagioclase and hornblende...69

Figure 4.9 Sagenitic texture developed in HBG biotite (a, b) very fine grained rounded

titanite (Tn) inclusions in biotite along grain boundaries and fractures, whereas the acicular inclusions forming sagenitic texture with three-sets of Tn inclusion lines intersecting each other almost at 60o. Note the asterisks-like features in highlighted box………………………………………………………………………………...70

Figure 4.10 Mineral paragentic sequence in GGn (a) and HBG (b). ?----? ─ represents

likely restitic core and further primary growth over it…………………………….72 Figure 4.11 Modal compositions of GGn (○) and HBG (∆) in the QAP diagram (Le

Maitre, 2002). Q-Quartz, A-Alkali feldspar, P-Plagioclase. Fields: 1a-Quartzolite, 1b, Quartz-rich granite, 2-Alkali feldspar granite, 3a-syenogranite, 3b-monzogranite, 4-granodiorite, 5-Tonalite, 6-Alkali feldspar syenite, 7-Syenite, 7΄-Quartz syenite, 8-Monzonite, 8΄-Quartz monzonite, 9-Monzodiorite, Monzogabbro, 9΄-Quartz monzodiorite, quartz monzogabbro, 10-Diorite, gabbro, anorthosite, 10΄ Quartz diorite, quartz gabbro, quartz anorthosite

Figure 5.1 Albite-Orthoclase-Anorthite triangular diagram showing compositions of

analyzed plagioclase and K-feldspar from representative GGn (○) and HBG (∆) samples……………………………………………………………………………79

Figure 5.2 Mg/(Mg+Fe+2) vs. Si (pfu) apmhibole classification diagram for HBG

amphiboles (after Leake et al., 1997) classifying HBG amphiboles as magnesiohornblende………………………………………………………………81

Figure 5.3 Annite, oxyannite and phlogopite ternery diagram (after Beane, 1974, modified

from Heinrich, 1946 and Foster, 1960) showing the primary crystallization of biotites of both GGn (О) and HBG (∆). Field A: primary biotites and field B: hydrothermal biotites, shown after Foster (1960). The Fe2SiO4-SiO2-Fe3O4 (FMQ), Ni-NiO (NNO) and Fe3O4-Fe2O3 (HM) buffers of biotite stability are shown after Wones and Eugster, (1965)……………………………………………………….84

Figure 5.4 (AlVI+Fe3++Ti)-Mg-(Fe2++Mn) ternary classification diagram for Phlogopite-

Lepidomelane series for the GGn (О) and HBG (∆) biotites, where A: phlogopite, B: Mg-biotite, C: Fe2+-biotite, D: siderophyllites and lepidomelane are shown after Foster, (1960)…………………………………………………………………….85

Figure 5.5a Binary Mg-Li vs. Fe (tot)+Mn+Ti-AlVI plot (Tischendorf et al., 1997) used to

classify the GGn (О) and HBG (∆) biotites. GGn biotites show composition in Fe-biotite and siderophyllite fields whereas HBG biotites are transitional between Mg- and Fe-biotites. Fields 1: Muscovite, 2: Li muscovite, 3: Lepidolite, 4: Zinnwaldite, 5: Li phengite, 6: Pnengite, 7: (Alumino-Mg-biotite), 8: Alumino-phlogopite, 9:

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Phlogopite, 10: Mg biotite, 11: Fe biotite, 12: Siderophyllite, 13: Protolithionote, 14: Lepidomelane…………………………………………………………………85

Figure 5.5b R3+-Li-R2+ ternary diagram after Foster (1960) suggesting siderophyllite-rich

GGn biotites (○) and siderophyllite to protolithionite nature of HBG biotite (∆). Different muscovite fields are shown after Monier and Robert (1986) and Stone et al. (1988)………………………………………………………………………….86

Figure 5.6 FeO(t)-MgO-Al2O3 triangular diagram after Albuquerque (1973) showing fields

of biotite coexisting with different mineral associations. Fields a: biotite coexisting with amphibole, b: biotite coexisting with other ferro-magnesian minerals, c: biotite coexisting with muscovite, and d: biotite coexisting with aluminosilicates. Note the GGn biotites (○) association with b and HBG biotites (∆) c fields………………87

Figure 5.7a Fe/Fe+Mg vs. Al (IV) plot of GGn (O) and HBG (∆) biotites showing

phlogopite-annite-siderophyllite-eastonite end-members (Deer et al., 1963) suggesting siderophyllite-rich nature of GGn-biotites where as HBG-biotites are transitional between siderophyllite and eastonite…………………………………88

Figure 5.7b Biotite compositions of GGn (○) and HBG (∆) classified in terms of ternary

Al-Mg-Fe(t) components. The end-members and various fields are shown after Deer et al. (1963)………………………………………………………………….88

Figure 5.8. Compositions of analyzed muscovites from GGn in terms of Ti, Mg and Na

(after Miller et al., 1981; Monier et al., 1984)…………………………………….90 Figure 5.9a Plot of RG muscovites (○) in ternary R3+-Li-R2+ diagram (Foster, 1960;

Monier and Robert, 1986; Stone et al., 1988) classifying them as lithian muscovite, lepidolite and zinnwaldite. Solid line with arrow heads represents transitional series between muscovite and zinnwaldite (Monier and Robert, 1986) showing composition of ferrous aluminium lithium micas…………………………………90

Figure 5.9b Binary Mg-Li vs. Fe (tot)+Mn+Ti-AlVI plot (Tischendorf et al., 1997) used for

classifying the RG muscovites (o). Various fields of muscovite based on estimation of lithium content are shown after Tischendorf et al. (1997). Fields 1: Muscovite, 2: Li muscovite, 3: Lepidolite, 4: Zinnwaldite, 5: Li phengite, 6:Pnengite, 7: (Alumino-Mg-biotite), 8: Alumino-phlogopite, 9: Phlogopite, 10: Mg biotite, 11: Fe biotite, 12: Siderophyllite, 13: Protolithionote, 14: Lepidomelane. ……………..91

Figure 5.10 Tourmaline classification in terms of principal constituents X-site vacancy-Ca-

Na (+K) ternary diagram (Hawthorne and Henry, 1999) classifying GGn-tourmaline into alkali group……………………………………………………….

Figure 5.11 Plot of Ca/(Ca + Na) versus Fe/(Fe + Mg) in tourmalines from GGn showing

composition of schorl………………………………………………………………

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Figure 5.12a Discrimination Al-Fe(t)-Mg ternary diagram for GGn-tourmalines, where 1: Li-rich granitoids, pegmatites and aplites. 2: Li-poor granitoids and their associated pegmatites and aplites. 3: Fe3+-rich quartz–tourmaline rocks (hydrothermally altered granites). 4: Metapelites and metapsammites coexisting with an Al-saturating phase. 5: Metapelites and metapsammites not coexisting with an Al-saturating phase. 6: Fe3+-rich quartz–tourmaline rocks, calc-silicate rocks, and metapelites. 7: Low-Ca meta-ultramafic rocks and Cr-, V-rich metasediments. 8: Metacarbonates and metapyroxenites. Note the overlap of fields 4 and 5 with field 7 (after Henry & Guidotti 1985)………………………………………………………

Figure 5.12b Fe(t)-Ca-Mg ternary plot (after Henry and Guidotti, 1985) for GGn

tourmalines. Fields represent 1: Li-rich granitoid pegmatites and aplites, 2: Li-poor granitoids and their associated pegmatites and aplites, 3: Ca-rich metapelites, metapsammites, and calc-silicate rocks, 4: Ca-poor metapelites, metapsammites, and quartz-tourmaline rocks, 5: Metacarbonates and, 6: Metaultramafics. ................. .

Figure 5.13 Geochemical composition of the GGn-tourmaline samples in MgO vs.

FeO/(FeO+MgO) plot (Pirajno and Smithies, 1992), where GGn-tourmaline showing intermediate to proximal endogranitic affinity (Field A: Endogranitic proximal, B: proximal to intermediate, C: distal). ........................................................ .

Figure 5.14 Or-Ab-an ternary plot showing the isothermo curves for GGn and HBG

calculated from different models with the help of program SOLVCALC 2.0 . ............. Figure 5.15 Log fO2 (bar) vs temperature (ºC) of biotite stability at P=2070 bar (Wones and

Eugster, 1965) plotted for HBG biotites stabilized at FMQ and NNO buffers. The curves labeled ‘O’ represent maximum phlogopite stability in terms of 100*Fe/Fe+Mg of biotite. The arrow shows a slightly oxidized trend for HBG biotites. ............................................................................................................................

Figure 6.1 A -B diagram (Debon and Le Fort, 1983) plotted for GGn and HBG. Each of six

sectors numbered I to VI corresponds to a specific mineral assemblage. I, II and III are peraluminous sectors, where I: muscovite > biotite (by volume), II: biotite > muscovite; III: biotite (usually alone, at times with a few amphiboles); IV, V and VI are metaluminous sectors, where IV: biotite+amphibole+pyroxene; V: clinopyroxene+amphibole+biotite; VI: unusual rocks (e.g. carbonatites). LG represented leucogranite field. Arrow with solid line shows trend for Lesser Himalayan granitoids of Nepal-India-Pakistan (Le Fort et al., 1980 in Barbarin, 1996). ..............................................................................................................................

Figure 6.2 Molar A/CNK vs. molar A/NK plots for GGn and HBG. The peraluminous,

metaluminous and peralkaline fields are shown after Maniar and Piccoli (1989).Error! Bookmark not defined. Figure 6.3 R1-R2 multicationic diagram (De la Roche et al., 1980) showing fields for

different igneous rock types. GGn (○) showing an evolution trend from monzo to

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syenogranite whereas HBG (∆) is confined to granodiorite field with few samples in monzogranite field. .....................................................................................................

Figure 6.4 Harker variation diagram plotted for the major oxides (a) TiO2, (b) Al2O3, (c)

Fe2O3, (d) MgO, (e) CaO, (f) Na2O, (g) K2O, and (h) P2O5 of GGn. ........................... Figure 6.5 CIPW norm based An–Ab–Or (O'Connor, 1976) plot classifying GGn (○) into

granite and HBG (∆) into granodiorite to trondhjemite fields. ..................................... Figure 6.6 (a-i) Harker variation plots for major oxides for HBG samples, in figure (c) the

grey field represents the experimental melt derived from the basaltic slab (after Rapp et al., 1991; Winther and Newton, 1991; Sen and Dunn, 1994; Rapp and Watson, 1995). (j) (Na2O+K2O) vs. SiO2 diagram (McDonald and Katsura, 1964) where grey field is for adakites (after Martin, 1999) showing that HBG samples fall in the arc calc-alkaline domain and overlapping the adakitic field also. Al=alkaline; Ca=Calc-alkaline; Th=tholeiitic. ....................................................................................

Figure 6.7 (a-c) Harker’s variation plots for selected LIL (Ba, Rb, Sr), and HFS (Zr, Y, Nb,

Th, U) elements of GGn (○) against SiO2. .................................................................... Figure 6.8 (a-f) Variation plots of selected trace elements for the HBG samples (∆), (g)

negative correlation between Mg# and SiO2, and (h) variation plot for Mg# and Cr/Ni ratio showing negative trend. .........................................................................................

Figure 6.9 Primitive mantle-normalized (Taylor and McLennan, 1985) extended (trace and

rare earth element) spidergrams plotted for GGn (a) and HBG (b) samples. ............... Figure 6.10 Comparison of chondrite normalized rare-earth elements patterns of (a) GGn

(b) HBG. Normalizing factors of chondrite are taken after Sun and McDonough (1989). .............................................................................................................................

Figure 6.11 Tectonic discrimination diagram based on major cations (after De La Roche et

al., 1980) of GGn and HBG. .......................................................................................... Figure 6.12 Trace element tectonic discrimination plot (Pearce et al., 1984) suggesting arc

to syn-collisional teconic setting for HBG and GGn melts with anomalous granite nature of few GGn samples ............................................................................................

Figure 6.13 Trace element tectonic discrimination plot (Pearce et al., 1984) suggesting arc

teconic setting for HBG and syn-collisional tectonic setting for GGn melts with with some overlapping of GGn in with in plate (WPG) and arc tectonic fields (VAG). ............................................................................................................................

Figure Figure 6.14 (a) Zircon U–Pb Concordia for GGn , (b) mean weighted age of

concordant ages of the GGn and (c) Zircon U–Pb Concordia for HBG, and (d) mean weighted age of concordant ages of the (HBG)…………………………...

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Figure 6.15 Zircon Hf isotopes and model ages of GGn (a, b) and HBG (c, d). See text for explaination ...............................................................................................................

Figure 7.1 Percent frequency distribution of magnetic susceptibility of felsic magmatic

rocks of western Arunachal Himalaya (Kumar and Pathak, 2009). Figure 7.2 Fe2O3/FeO vs SiO2 (wt%) plot of granitoids (after Ishihara et al., 1979) from

western Arunachal Himalaya (Kumar and Pathak, 2009). ............................................ Figure 7.3 Log10 Fe2O3/FeO vs FeO* plot of granitoids from western Arunachal

Himalaya. Various fields of VSO (Very Strongly Oxidized), SO (Strongly Oxidized), MO (Moderately Oxidized), MR (Moderately Reduced), and SR (Strongly Reduced) are taken from Hart et al. (2004). ..................................................

Figure 7.4 (a) MgO vs FeOt diagram (after Abdel-Rahman, 1994) classifying the GGn (О)

and HBG (∆) biotites in peraluminous (S-type) suits and HBG (∆) biotites in calc-alkaline, metaluminous (I-type) suits. A negative correlation is shown by biotites of both GGn and HBG, (b) Al2O3-FeOt diagram (after Abdel-Rahaman, 1994) discriminating the nature of biotites of GGn (О) and HBG (∆), and (c) Al2O3 vs MgO variation diagram (after Abdel-Rahaman, 1994) used for GGn (О) and HBG (∆) biotites.

Figure 7.5a. [VI]Fe + [IV]Si vs. Al[IV] + Al[VI] plot for GGn muscovites (o) showing the

probable exchange mechanism of [4]Si [4]Al3+-1 [6]Fe2+ [6]Al3+-1. Figure 7.5b Chemical variation of GGn muscovites (o) suggesting likely substitution

between Al3+ and Fe, Mg2+, minor amounts of Ti4+, Mn2+ . .......................................... Figure 7.6. Negative correlation between total aluminium and Fm (Fe2++Mg) of GGn

muscovite suggesting the control of peraluminousity of bulk rock over the composition of muscovite (Zane and Rizzo, 1999). ......................................................

Figure 7.7 (R++ R2+) versus R3+ variation plot in tourmaline from GGn, where variation can

be related to ploton-loss substitutions in tourmaline. The lines represent compositions between unsubstituted schorl-dravite and the fully substituted end-members (proton-loss and alkali-defect end-members) (Diagram after Roda et al., 1995 and references their in).

Figure 7.8 Binary Mg vs Fe(t) plot after London and Manning (1995) plotted for GGn-

tourmaline showing Mg⇄Fe substitution along Schorl-Dravite solid solution end members.

Figure 7.9 CIPW normative Qz–Ab–Or ternary plot for GGn samples where solid star is

the average composition of GGn (after Johannes and Holtz, 1996). Solid lines are cotectic lines and eutectic minima at 1, 5 and 10 kbar under H2O-saturated conditions.

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Figure 7.10 Variation diagram plotted for Fe2O3 + MgO + TiO2 (wt %) against Zr (ppm)

from whole-rock data for GGn and HBG. Figure 7.11 (a) (La/Yb)N versus YbN plot suggesting the transitional nature of HBG melt

between classical island arc and adakites, (b) Sr/Y versus Y plot classifying HBG as classical island arc melt (adakite field are from Defant and Drummond, 1990) and (c) In SiO2 versus MgO plot HBG corresponds to high-silica adakite field. Low-silica and high-silica adakite fields are after Martin et al., 2005.

Figure 7.12 Comparision of chondrite normalized rare-earth elements patterns of HBG,

Early, Mid and Late Archean TTG and high-silica adakites (after Martin et al., 2005 and references their in). Normalizing factors of chondrite are after Sun and McDonough (1989). The HBG is showing similar petrochemical characteristics to those of the Archean TTG.

Figure 7.13(a) MgO-SiO2 plot suggest delaminated lower crust as probable protolith for

HBG (fields are after Zhao and Zhan, 2008), (b) Molar (Al2O3/MgO+FeOt)-(CaO/ MgO+FeOt) plot showing metabasic to tonalitic source for HBG (fields are after Altherr et al., 2000) ....…………………………………………………………..158

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List of tablesList of tablesList of tablesList of tables

Page

Table 1.1 Precambrian granite magmatism in India. 6

Table 2.1 Magnetic susceptibility (MS) values (in × 10-3 SI unit) of felsic lithounits of

western Arunachal Himalaya measured in various localities. 52

Table 5.1 Electron probe micro analysis (wt%) and structural formulae of Feldspars from

Bomdila Ms-Bt granite gneiss (GGn).......................Error! Bookmark not defined.

Table 5.2 Electron micro probe analysis (wt %) and structural formulae of feldspars

from Salari Hbl-Bt granite (HBG) Error!

Bookmark not defined.

Table 5.3 Electron micro probe analysis (wt %) and structural formulae of amphiboles

from Salari Hbl-Bt granite (HBG) ............................Error! Bookmark not defined.

Table 5.4 Electron probe micro analysis (wt %) and structural formulae of biotites from

Bomdila Ms-Bt granite gneiss (GGn).......................Error! Bookmark not defined.

Table 5.5 Electron probe micro analysis (wt %) and structural formulae of biotites from

Salari hornblende-biotite granite (HBG) ..................Error! Bookmark not defined.

Table 5.6 Electron microprobe analysis of representative muscovites from GGn. ….. 97

Table 5.7 Electron microprobe analyses and calculated formulae of representative

tourmalines hosted in Bomdila Ms-Bt granite gneiss (GGn). ………………….100

Table 5.8 Tourmaline species currently accepted by the IMA-CNMNC. ……………103

Table 5.9 Al-in-hornblende geobarometer calculated for HBG samples……………...105

Table 5.10 Hornblende-plagioclase geothermometer used to calculate hbl-pl equilibration

temperature of HBG. ……………………………………………………………106

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Table 5.11 Two-feldspar thermometers calculated for GGn and HBG calculated from

various models……………………………………………………………….107

Table 6.1: Major (wt%) and trace(ppm) element data for the samples of GGn (Ms-Bt

Bomdila Gneiss)……………………………………………………………..114

Table 6.2.: Major (wt%) and trace(ppm) element data for the samples of Hbl-Bt granite

(Salari Granite). ……………………………………………………………. 117

Table 6.3. Zircon LA-ICP-MC U–Pb data of Bomdila Ms-Bt granite gneiss (GGn) from

Kameng district, western Arunachal Himalaya. ……………………………134

Table 6.4. Zircon LA-ICP-MC U–Pb data of Salari Hbl-Bt granite (HBG) from Kameng

district, western Arunachal Himalaya. ……………………………………...135

Table 6.5. Hf isotopic data for zircons from host Bomdila Ms-Bt granite gneiss (GGn)

and Salari Hbl-Bt granite (HBG) from Kameng district of western Arunachal

Himalaya. ……………………………………………………………………136

Table 6.6. Hf isotopic data for zircons from host Salari Hbl-Bt granite (HBG) from

Kameng district of western Arunachal Himalaya. …………………………..137

Table 7.1. Summary of field, petrography, mineralogy, chemical and isotopic results of

Bomdila ms-bt granite gneiss (GGn) and Salari hbl-bt granite (HBG) from

western Arunachal Himalaya. ……………………………………………….139

Table 7.2a Major elements based solution of residual (BMD 28) melt from B9 parent B9

parental GGn melt after fractionating bt-pl-kf-mgn-ttn-ap mineral assemblages.

………………………………………………………………………………….153

Table 7.2b. Composition of calculated major (wt%) and trace elements (ppm) daughter

melt with those of observed daughter. …………………………………………153

Table 7.3a Calculation of residual (S10C) melt from S9B parent (assumed) melt after

fractionating hbl-bt-pl-kf-ap-mineral assemblage……………………………..154

Table 7.3b. Trace element modelling for the S9B and S10C melts considered as parent

and residual respectively. …………………………………………………….155

Table 7.4 Comparison of the geochemical features of HBG melt with adakite. ……..156

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