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Pradhan, A. K.
- Geochemistry and Petrogenesis of Anorogenic(?) Granitoids of West Garo Hills, Meghalaya
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Authors
Affiliations
1 Atomic Minerals Directorate for Exploration & Research, Jamshedpur - 831 002, IN
2 Atomic Minerals Directorate for Exploration & Research, Shillong, IN
3 Atomic Minerals Directorate for Exploration & Research, Bangalore, IN
4 Atomic Minerals Directorate for Exploration & Research, Hyderabad, IN
1 Atomic Minerals Directorate for Exploration & Research, Jamshedpur - 831 002, IN
2 Atomic Minerals Directorate for Exploration & Research, Shillong, IN
3 Atomic Minerals Directorate for Exploration & Research, Bangalore, IN
4 Atomic Minerals Directorate for Exploration & Research, Hyderabad, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 80, No 2 (2012), Pagination: 276-286Abstract
The granite in Samingiri - Dilsekgiri area occurs as discordant, isolated pluton within the migmatitic terrain of West Garo Hills district, Meghalaya. The pluton is exposed over 140 sq km (18 km × 8 km). It exhibits structures of solid state and piecemeal stoping effect proximal to the contact and enveloped by a contact metamorphic aureole of albite-epidote-hornfels facies. Modally, it is biotite-monzogranite and biotite-syenogranite with minor biotite, chlorite, epidote and sericite and accessories like zircon, apatite, allanite, pyrite, magnetite and sphene. Geochemically, it is marked by restricted composition (69-76 wt% SiO2), high alkalies, low Ca, metaluminous to strongly peraluminous (Molar Al2O3/CaO+Na2O+K2O = 0.95-1.54), high FeO/MgO, high Ga/Al, high contents of Rb, Sr, Ba, Y, Zr and Ce and depleted in Ti and P. The field observation, mineralogical and geochemical aspects indicate the post-tectonic nature of West Garo pluton more like as A-type granite formed by partial melting of lower crustal blocks followed by low to moderate degree of fractional differentiation. Low Ca, alkaline nature and peraluminous character point to A-type nature of West Garo granite significantly different from other granites of Meghalaya Plateau. Rb-Sr age (616 ± 86 Ma) of granite, however, corresponds to widespread Middle to Upper Pan African activity, a thermal event prevailed during Late Proterozoic - Early Palaeozoic (500-800 Ma) period, manifested in the form of several granitic intrusions in the basement gneissic complex and the overlying Proterozoic metasediments of the Shillong Group in Meghalaya Plateau.Keywords
West Garo Granite, Shillong Group, Meghalaya, Pan African Activity.
References
- BILLINGS, M.P. (1997) Structural Geology. 3rd Edition, Eastern Economy Edition, (c) 1972 by Prentice-Hall, Inc., Englewood Cliffs, NJ, U. S. A.
- CHAKI, A., BASU, A.N. and RAWAT, T.P.S. (1992) Petrogenesis of the uranium mineralized granitoids of Nangalbibra-Siju area, Garo Hills, Meghalaya, India. Explor. Res. At. Minerals, v.5, pp.13-25.
- CHIMOTE, J.S., PANDEY, B.K., BAGCHI, A.K., BASU, A.K., GUPTA, J.N. and SARASWAT, A.C. (1988) Rb-Sr Whole Rock Isochron Age for the Mylliem Granite, East Khasi Hills, Meghalaya. Proc. 4th Natl. Symp. on Mass Spectrometry, Bangalore.
- COLLINS, M.J., BEAMS, S.D., WHITE, A.J.R. and CHAPPELL, B.W. (1982) Nature and origin of A-type granite with particular reference to Southeastern Australia. Contrib. Mineral. Petrol., v.80, pp.189-200.
- CURIE, K.L. (1976) The alkaline rocks of Canada. Geol. Surv. Can. Bull. pp.239.
- DHANA RAJU, R., PANEER SELVAM and SINHA, R.M. (1996) Petrology and geochemistry of the Neoproterozoic South Khasi batholith and related granitoids in the Khasi Hills districts, Meghalaya, India, and their bearing on uranium mineralization. Explor. Res. Atomic Minerals, v.9, pp.73-89.
- EL BOUSEILY, J.D. and EL SOKKARY, A.A. (1975) The relation between Rb, Ba and Sr in granitic rocks. Chemical Geol., v.16, pp.207-219.
- GHOSH, SUBHASHISH. CHAKRABORY, S., BHALLA, J.K., PAUL, D.K., SARKAR, A., BISHUI, P.K. and GUPTA, S.N. (1991) Geochronology and geochemistry of granite plutons from East Khasi Hills, Meghalaya. Jour. Geol. Soc. India, v.37, pp.331-342.
- GHOSH, SUBHASHISH, CHAKRABORY, S., BHALLA, J.K., PAUL, D.K., SARKAR, A., BISHUI, P.K. and GUPTA, S.N. (1994) New Rb-Sr isotopic ages and geochemistry of granitoids from Meghalaya and their significance in middle to late Proterozoic crustal evolution. Indian Minerals, v.48 (1 & 2), pp.33-44.
- JACKSON, N.J., WALSH, J.N. and PEGRAN, E. (1984) Geology, geochemistry and petrogenesis of late Precambrian granitoids in the Central Hijaz Region of the Arabian Shield. Contrib. Mineral. Petrol., v.87, pp.205-219.
- KUMAR, S. and PIERU, T. (2010) Petrography and major elements geochemistry of microgranular enclaves and Neoproterozoic granitoids of South Khasi, Meghalaya: evidence of magma mixing and alkali diffusion during mingling of hybrid globules. Jour. Geol. Soc. India, v.76, pp.345-360.
- KUMAR, S., PIERU, THEPFUVILIE, RINO, VIKELENO and LYNGDOH, B.C. (2005) Microgranular enclaves in Neoproterozoic granitoids of South Khasi Hills, Meghalaya plateau, Northeast India: Field evidence of interacting coeval mafic and felsic magmas. Jour. Geol. Soc. India, v.65, pp.629-633.
- LOISELLE, M.C. and WONES, D.R. (1979) Characteristics and origin of anorogenic granites. Geol. Soc. Amer. Ann. Meeting, Abstracts, pp. 468.
- MAZUMDER, S.K. (1976) A summary of the precambrian geology of the Khasi Hills, Meghalaya. Geol. Surv. India, Misc. Publ., no.23, pt.2, pp.311-334.
- NAKAMURA, N. (1974) Determination of REE, Ba, Fe, Mg, Na and K in carbonaceous and ordinary chondrites. Geochimica Cosmochimica Acta. v.38, pp.757-775.
- NANDY, D.R. (2001) Geodynamics of Northeastern India and the adjoining region, ACB publications.
- PEARCE, J.A., HARRIES, N.B.W. and TINDLE, A.G. (1984) Trace elemental discrimination diagrams for the tectonic interpretations of granitic rocks. Jour. Petrol., v.25, pp. 956-983.
- SARKAR, S., KHONGLA, M.A., KHAN, M.A., KUMAR, T.B.R. and RAY, J.N. (2007) Polymodal occurrence of early mafic differentiate associated with mid-proterozoic calc-alkaline plutons of Meghalaya. Jour. Geol. Soc. India, v.70, pp.53-58.
- SHAND, S.J. (1943) Eruptive Rocks. Their Genesis, Composition, Classification and their relation to Ore deposits with a chapter on meteorite. New York. John Wiley & Sons.
- STRECKEISEN, A. (1976) To each plutonic rock its proper name. Earth Sci. Rev., v.12, pp.1-33.
- SUNIL KUMAR (1990) Petrochemistry and geochronology of pink granite from Songsak, East Garo Hills district, Meghalaya. Jour. Geol. Soc. India, v.35, pp.39-45.
- TAYLOR, R.P., STRONG, D.F. and KLEAN, B.F. (1980) The Topsailss igneous complex: Silurian-Devonian peralkaline magmatism in Western Newfoundland. Can. Jour. Earth Sci., v.17, pp.425-439.
- TUREKIAN, K.K. and WEDEPOHL, K.H. (1961) Distribution of the elements in some major units of the earth’s crust. Bull. Geol. Soc. Amer., v.72, pp.175-192.
- WHALEN, J.B., CURIE, K.L. and CHAPPELL, B.W. (1987) A-type granites: geochemical characteristics, discrimination and petrogenesis. Contrib. Mineral. Petrol., v.95, pp.401-419.