P.V.N. Rao, A.T. Rao
Email ID Not Available
Department of Geology, Nagarjuna University, Nagarjunanagar-522510, Guntur, A.P
Department of Geology, Andhara University, Waltair-530 003, A.P.
Volume - 5,
Issue - 1,
Year - 1992
Leptynites are important rock type in the Visakhapa1nam area and they are categorised into grey and cream varieties. At a glance it is noticed from the data that the radioelement concentrations in grey leptynites are lower while they are higher in the cream leptynites. The concentrations of U, Th, K and Th/U ra1ios of grey leptynites do not represent the primary distribution but indicate their expulsion in a hydrous partial melt from the destabilised mineral sites/ dislocations of k-feldspar, biotite and other accessory phases. The expelled U, Th, K and other LIL elements during granulite facies metamorphism were carried up in hydrous granitic partial melts along weak shear planes/zones and crystallized in surrounding cream leptynites. The enrichment of radioelements in the cream leptynites may be po5$ible by two reascne: 1. Crystallization of radioelement bearing partial melts in the cream leptynites. 2. The radioelement already resided in the accessory phases present in cream leptynites. The expulsion of U, Th and K from grey leptynites during granulite facies metamorphism is simultaneously followed by the crystalization of partial melts in the cream variety. The higher rediogenic heat generatlon (2.17) values of leptynites reveals that the Precambrian crust of the Eastern Ghats Granulite Terrain characterised by high radioactivity.
Cite this article:
Rao and Rao (1992). Radioelement distribution in Leptynites from Eastern Ghat Granulite Terrain. Journal of Ravishankar University (Part-B: Science), 5(1), pp.77-83