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Authors
Affiliations
1 Department of Geosciences, Osaka City University, Osaka 558-8585, JP
2 Deparlrnent of Earth and Planetary Systems and Science, Hiroshima University, Higashi-Hiroshima 739-8526, JP
3 Department of Geology, Kuwait University, KW
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 56, No 1 (2000), Pagination: 67-78
Abstract
Amphibolites from the Nellore-Khammam schist belt, Khammam district, Andhra Pradesh, were metamorphosed at 700 ± 50 °C, 1.1 ± 0.1 GPa. Bulk-rock chemical characteristics for relatively immobile element ratios (e.g. Zr-Y-Ti) of the amphibolites suggest two different tectonic settings: oceanic island arc and continental margin island arc affinities. Coexistence of rocks for two different tectonic settings in the schist belt can be explained by accretion at trench as protoliths of the highpressure metamorphic amphibolites. Because the Nellore-Khammam schist belt is located between two terrains, such as Dhanvar Craton and Eastern Ghats Granulite Terrain, their mode of occurrence implicitly suggests that formation of the Nellore-Khammam schist belt was related to the continentcontinent collision tectonics. Consequently, the Nellore-Khammam schist belt may have formed at Ieast in two steps: (1) accretion of the rocks originating from different tectonic settings at trench and (2) subsequent high-pressure metamorphism and exhumation of the rocks caused by collision tectonics.
Keywords
Petrology, Geochemistry, P-T Conditions, Amphibolites, Nellore-Khammam Schist Belt, Andhra Pradesh.
