Petrogenesis of Amgaon Gneiss from the Northwestern Part of the Bastar Craton

Mandal, Sourav (2021) Petrogenesis of Amgaon Gneiss from the Northwestern Part of the Bastar Craton. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Sourav Mandal (16MS091)) 16MS091_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

The formation mechanism and tectonic setting of the Archean carton are highly debated issues. A major part of the Archean craton is dominantly consisting of granitiods (mostly tonalite-trondhjemite-granodiorite or TTG and, granite) and greenstone belts. Several generation of granitoids are preserved in the Bastar craton. This study presents high-precision major and trace element data on granitoids from the relatively less-studied northwestern part near Gadchiroli area to understand their petrogenesis. The granitiods are present in this area are classified as sodic (TTG) and K-rich (granite) groups. The granitoids are characterized by low Mg#, low ferromagnesian contents, enrichment in LILE, depleted HFSE with negative Nb, Ta, Ti anomaly, and fractionated LREE, a flat HREE pattern, negative Eu anomaly and, low Sr/Y. It is interpreted that the TTGs were formed by partial melting of a low-K mafic rock at at low pressure and shallow depth and the K-rich granites were formed by the partial melting of a heterogeneous source consisting of, tonalite and metasediment at low pressure and shallow depth.

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