Geochemistry and Origin of Metasedimentary Rocks of Veligallu Greenstone Belt, Eastern Dharwar Craton

Dutta, Dhrubadyuti (2021) Geochemistry and Origin of Metasedimentary Rocks of Veligallu Greenstone Belt, Eastern Dharwar Craton. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Dhrubadyuti Dutta (16MS104)) 16MS104_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (3MB)

Abstract

Nature of Neoarchean crust in Eastern Dharwar Craton (EDC) is highly debated issue. Sedimentary rocks, being an important archive of the then existing continental crust can provide important clues to the nature of the Neoarchean crust of EDC. TheVeligallu greenstone belt, located south of Cuddapah basin consists significant amount of meta-sedimentary rocks classified as quartz-muscovite schist. This study presents major and trace element data on the quartz-muscovite schists to understand the nature of their source rock, paleoweathering pattern and tectonic setting of their deposition. The Veligallu metasedimentary rocks (quartz-muscovite schists) are identified as metamorphosed shale; they are enriched in Al, K and depleted in Ca, Na and Mg with respect to Archean average shale. The rocks show prominent negative Eu anomaly and flat HREE pattern. The CIA values (76 to 84) indicates that the rocks were derived from a moderately weathered source. Discrimination plots utilizing immobile incompatible trace elements like Th, Sc, Zr, Ti and compatible elements like Cr, Ni, V suggest the source rock of the sediments to be mainly felsic composition produced by shallow intracrustal melting. The sediments were possibly deposited in a continental arc setting.

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