1 GSI Misc. Pub. 30 Pt. 4 Vol. 2(i) PGSI-315 700-2010 DSK-II GEOLOGY AND MINERAL RESOURCES OF ARUNACHAL PRADESH GEOLOGICAL SURVEY OF INDIA Miscellaneous Publication No. 30 Part IV Vol I(i) Arunachal Pradesh Published by the order of the Government of India 2010 2 CopyGSI Misc. right Pub. © India,30 Pt. 4 Geological Vol. 2(i) Survey, 2010 GEOLOGY AND MINERAL RESOURCES OF ARUNACHAL PRADESH Compiled by G. K. KESARI Senior Geologist under the guidance of G. DAS GUPTA Dr. H.S.M. PRAKASH Director AND Superintending Geologist Publication Division Publication Division Under the overall supervision by B.K. MOHANTY SUDIPTA LAHIRI J.N. RAY Ex-Dy. Director General Ex-Dy. Director General Dy. Director General Geological Survey of India NORTH EASTERN REGION Shillong- 793 003 Price: Inland : Rs. 91/- Foreign : £ 3.11 or $ 4.76 Printed at ESSAR OFFSET, Janapath Lane, G.S. Road, Ulubari, Guwahati-781007, Mobile : +91-9435106080 3 GSI Misc. Pub. 30 Pt. 4 Vol. 2(i) FOREWARD The Miscellaneous Publication 30 Series of the Geological Survey of India brings out concise information on the geology and mineral resources of the states of India. The present volume Part IV, Vol. 2(i) of the series, pertaining to the state of Arunachal Pradesh, is a revised and updated version of the first edition published in 1974. During the span of three and a half decades since the first edition was pub- lished, enormous knowledge has been added in the sphere of geology of the area warranting of a revised edition of this volume. Thus Geological and Mineral Map presented in this volume is a modified version incorporating 1:2 million scale Geo- logical Map of North-East India (1998). Geological Survey of India continues its dedicated work in different realms of Earth sciences. Revisions in the lithostratigraphic succession of the rocks have been necessary based on the recent advances in geological mapping and laboratory works. Occurrences of limestone and graphite in Lower and Upper Subansiri, West Siang and Lohit districts and clay, beryl and base metal mineralization near Potin village in Ranga valley of Lower Subansiri district of Arunachal Pradesh have evolved interest because of the indicated cobalt values in pyrite and nickel in pyrrhotite. In- vestigation for locating limestone-marble occurrences has resulted in the discovery of Tidding Limestone and Dora Marble deposits in Lohit district. The coal deposits of Namphuk in Tirap district was investigated by GSI and a reserve of 17 million tones with the help of drilling and about 100 million tonnes in the indicated category has been established. This publication with update knowledge-base on the geology and mineral resources of the state of Arunachal Pradesh will be of immense use to the students of geology as well as to the professionals and entrepreneurs interested to make in- vestment for developing mineral industry in the region. (N. K. DUTTA) Director General PLACE : Kolkata Geological Survey of India 4 GSI Misc. Pub. 30 Pt. 4 Vol. 2(i) CONTENTS GSI Misc. Pub. 30 Pt. 4 Vol. 1(i) Page INTRODUCTION ................................................................................................................................ 1 (ii) Physiography .....................................................................................................................................................................2 (A) Himalayan Range ...................................................................................................................................................2 (i) Tibetan Himalaya ................................................................................................................................................................2 (ii) Higher Himalaya .................................................................................................................................................................2 (iii) Lesser Himalaya ..................................................................................................................................................................2 (iv) Sub-Himalaya .....................................................................................................................................................................3 (B) Trans-Himalayan Range ........................................................................................................................................3 (C) Naga-Patkoi Range ................................................................................................................................................3 (D) Brahmaputra Plain .................................................................................................................................................3 (iii) Drainage ............................................................................................................................................................................3 (iv) Climate, Forests and Cultivation .......................................................................................................................................3 (v) Accessibility .......................................................................................................................................................................3 (vi) Previous Work ...................................................................................................................................................................5 (vii) Landslides and Seismotectonics ........................................................................................................................................5 (viii) Acknowledgements ............................................................................................................................................................5 1.1 GEOLOGY OF THE HIMALAYAN BELT ................................................................................................ 6 A: PALAEO-PROTEROZOIC ............................................................................................................ 6 (i) Se La Group ...........................................................................................................................................................7 (ii) Bomdila Group ......................................................................................................................................................8 B: MESO-PROTEROZOIC .............................................................................................................. 10 (i) Dirang/Lumla Formation ................................................................................................................................... 10 C: NEO-PROTEROZOIC ................................................................................................................ 11 (i) Thingbu Formation .............................................................................................................................................. 11 (ii) Biotite Granite ..................................................................................................................................................... 11 D: PALAEOZOIC .......................................................................................................................... 11 (a) Lower Gondwana Group ..................................................................................................................................... 11 (i) Miri Formation .................................................................................................................................................... 11 (ii) Bichom Formation ............................................................................................................................................... 12 (iii) Lichi Formation ................................................................................................................................................... 13 (iv) Bhareli Formation ................................................................................................................................................ 13 (v) Abor Volcanics ..................................................................................................................................................... 14 (vi) Yamne Formation ................................................................................................................................................ 14 E: PALAEOGENE ......................................................................................................................... 15 (a) Yinkiong Group ................................................................................................................................................... 15 F: NEOGENE ............................................................................................................................... 15 (a) Tourmaline Bearing Leucogranite ....................................................................................................................... 15 (b) Siwalik Group ...................................................................................................................................................... 16 (i) Dafla Formation .................................................................................................................................................. 16 (ii) Subansiri Formation ...........................................................................................................................................