Affiliation:
1. Jadavpur University, India
Abstract
The Precambrian basement of the Schirmacher Hills records multiple episodes of deformation, metamorphism, migmatization, and emplacement of successive generations of mafic and felsic bodies. The earliest tectono-thermal event (D1/M1), preserved in some mafic and ultramafic enclaves, indicates deformation at great crustal depth. The mineralogical assemblage of these enclaves indicates early high temperature (900o C) and high-pressure (10 Kbar) granulite facies conditions. The second tectono-thermal event also showed deformation under granulite facies metamorphism (D2/M2) under 800-850oC and 8 Kbar. The third group of events (D3/M3) is the most dominant in this region and involved deformation under amphibolite facies conditions with synchronous emplacement of granites and mafic dykes and culminated in regional thrusting, producing a regional inversion where the granulates were emplaced over the amphibolite facies rocks. The later events created upright folds and vertical shear zones under amphibolite facies conditions.
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