Vesuvianite-wollastonite-grossular-bearing calc-silicate rock near Tatapani, Surguja district, Chhattisgarh

Abstract

This paper reports the occurrence of vesuvianite + wollastonite + grossular + diopside + microcline + quartz assemblage in an enclave of calc-silicate rocks occurring within quartzofeldspathic gneiss near Tatapani in the western part of Chhotanagpur Gneissic Complex. The enclave contains phlogopite-absent and phlogopite-bearing calc-silicate rocks, the latter being much more abundant than the former. The above assemblage occurs in the phlogopite-absent rock. Phlogopite-bearing rock contains the assemblage phlogopite + salite + microcline + plagioclase + quartz. A strong schistosity is developed in both the calc-silicate rocks and the minerals are syntectonic with the major foliation-forming event in the area. The vesuvianite-bearing assemblage is formed by amphibolite facies regional metamorphism of a calcareous protolith at pressure < 4kbar and XCO2 (fluid) < 0.15.