Relative chronology in high-grade crystalline terrain of the Eastern Ghats, India: new insights
S. Bhattacharya1, R. Kar2, A. K. Saw3, and P. Das41Indian Statistical Institute, Kolkata 700108, India 2J.K.College, Purulia 723101, India 3National Mineral Development Corporation Limited, Hyderabad 500173, India 4Uranium Corporation of India Limited, Turamdih 832107, India
Received: 08 Dec 2010 – Accepted for review: 16 Dec 2010 – Discussion started: 17 Jan 2011
Abstract. The two major lithology or gneiss components in the polycyclic granulite terrain of the Eastern Ghats, India, are the supracrustal rocks, commonly described as khondalites, and the charnockite-gneiss. Many of the workers considered the khondalites as the oldest component with unknown basement and the charnockite-protoliths as intrusive into the khondalites. However, geochronological data do not corroborate the aforesaid relations. The field relations of the hornblende- mafic granulite with the two gneiss components together with geocronological data indicate that khondalite sediments were deposited on older mafic crustal rocks. We propose a different scenario: Mafic basement and supracrustal rocks were subsequently deformed and metamorphosed together at high to ultra-high temperatures – partial melting of mafic rocks producing the charnockitic melt; and partial melting of pelitic sediments producing the peraluminous granitoids. This is compatible with all the geochronological data as well as the petrogenetic model of partial melting for the charnockitic rocks in the Eastern Ghats Belt.
Bhattacharya, S., Kar, R., Saw, A. K., and Das, P.: Relative chronology in high-grade crystalline terrain of the Eastern Ghats, India: new insights, Solid Earth Discuss., 3, 1-17, doi:10.5194/sed-3-1-2011, 2011.