A ~957 Ma Metamorphism in the Mesoarchaean Hindoli Group Supracrustal Rocks from the Jahazpur Shear Zone, East Rajasthan (India): Constraints from Sm-Nd Dating and Phase Equilibria Modeling

Abstract

ABSTRACT A petrological-chronological investigation of the Hindoli Group of rocks within the Jahazpur Shear Zone in the eastern segment of the Aravalli Delhi Fold Belt (ADFB), NW India, has been conducted. We infer two stages of deformation (D1 and D2) and metamorphism (M1 and M2) for the garnet - muscovite - biotiteschists interleaved with meta dolomite, Banded Iron Formation (BIF) amphibolite, and foliated granite. The D2 deformation corresponds to the northeast-trending Jahazpur shear zone on a regional scale. Garnet porphyroblasts, syntectonic with the D2 deformation, are chemically zoned with spessartine-rich cores. Geothermobarometry and pseudosection analyses yield peak P-T conditions of ~7.5 kbar, 580°C, followed by decompression and cooling along a clockwise P-T path. The Sm-Nd isotope analysis of the whole rock yields a date of ~3.0 Ga from an amphibolite. This data is interpreted as the age of formation of the litho-units of the Hindoli Group. Sm-Nd analyses of garnet grains yield an age of ~957 Ma. This date corresponds with the age of nucleation of the Jahazpur shear zone. A good correlation is established between the Neoproterozoic crustal segments of the Jiangnan Fold Belt of the South China Craton and that of the ADFB during the formation of the Rodinia Supercontinent.