Petrology and in-situ monazite geochronology of ultra-high temperature granulites from the Eastern Madurai Domain, Granulite Terrane of Southern India

Kharkongor, Melissa Bok Kharmujai (2018) Petrology and in-situ monazite geochronology of ultra-high temperature granulites from the Eastern Madurai Domain, Granulite Terrane of Southern India. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Melissa Bok Kharmujai Kharkongor (13MS026)) 13MS026.pdf - Submitted Version Restricted to Repository staff only Download (9MB)

Abstract

The Granulite Terrane of southern India (GTSI) is believed to be a microcontinental block which was bounded to the west by Madagascar and East African and to the east by Sri Lanka and Antarctica before it collided with the Indian subcontinent during the amalgamation of Gondwana. The Terrane is divided into different crustal units based on the difference in their evolution history: (1) Salem Block (2) Madurai Block (3) Trivandrum Block (4) Nagercoil Block (Santosh et al., 2009). The shear zone present in the terrane, Palghat Cauvery Shear System (PCSS) marked the boundary of the Salem block and other blocks in the terrane. However interpretations from different studies are very controversial based on PCSS being the suture zone. Therefore, this study is wholly directed to a region in the eastern Madurai domain which lies west of Madurai city near the town Usilampatti. Evidences from different studies that have reported UHT rocks which lies in the Khambam UHT belt (Brandt and Raith, 2014; Plavsa et al., 2012). Previous geochronological study is done and yielded ages of Neoarchaean to Palaeoproterozoic crust formation age and Pan-African high-grade metamorphism. However, a detailed characterization of the high-grade metamorphism and correlation with metamorphic ages from the same rocks using in-situ dating techniques was lacking.This is the first study for texturally-controlled in-situ monazite dating of a UHT metapelite from the EMD and we could establish three distinct stages of metamorphism. There is a correlation of the metamorphic textures and assemblage with the in-situ metamorphic ages to understand the metamorphic history. We have reported UHT rocks and it is a newly discovered UHT locality in the Madurai Block. Therefore this study will help in redefining the UHT belt in this terrane.

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