Petrogenesis of Dongargarh Granite from north-western part of Bastar Craton

Kujur, Amandeep (2023) Petrogenesis of Dongargarh Granite from north-western part of Bastar Craton. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (Ms dissertation of Amandeep Kujur (18MS185)) Thesis_18MS185.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

The Late Archean eon marks a significant transition in the global geological record with an accelerated rate of crust generation. A significant change in the granitoid chemistry and petrogenetic processes also characterizes this time period. Therefore, understanding the geochemical shifts in Archean granitoid is necessary to decipher the Archean geodynamic processes. Voluminous granitic magmatism has been recorded in the Bastar Craton at the Archean-Proterozoic boundary, which resulted in the emplacement of the Malanjhkhand, Dongargarh, and Kanker granitic plutons. In previous studies, multiple granitic bodies were classified as Dongargarh granite, supposedly synchronous with other granitic pluton emplacements. Two exclusively different granites are recorded in the north-western part of the main Dongargarh pluton near Amgaon, separated by the Amgaon Gneiss and the Khairagarh Group. These two bodies are different regarding field appearance, mineralogy, and chemistry. Northern granite (Thana granite) is more silicic and shows an A-type nature with high Fe/Mg, REE, and HFSE, in contrast to southern granite (Arjuni granodiorite), which shows an affinity towards I-type granite. The generation of A-type granite in close association with I-type granite makes the region interesting in light of global geodynamics concerning the Bastar Craton in the Archean-Proterozoic boundary.

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