Evolution of the “Central Indian Tectonic Zone”: A Critique Based on the Study of the Sausar Belt

Abstract

Detailed structural mapping carried out in different parts of the Central Indian Tectonic Zone (CITZ) combined with an analysis of spatio-temporal evolution of different domains have shown evolution in three tectono-thermal events. The felsic gneisses, referred as Tirodi Gneiss, belong to four generations. The oldest gneissic unit, Tirodi Gneiss—I (>2450 Ma), has development of a paleosol horizon at the top, which was involved in anoxic weathering, and forms the basement of the Sausar Group. The Sausar Group was deposited during the period ca. 2400–2250 Ma and contains glaciogenic sediments of Paleoproterozoic “snowball earth” event and ore-grade manganese deposits. The first deformation marked by the development of isoclinal folds with axial planar cleavage and coeval granulite facies metamorphism of the Sausar Group took place at ~2100 Ma, when grey gneisses and migmatites, Tirodi Gneiss—II, were developed. The upright to steeply inclined isoclinal folds in the Sausar Group with regional ~EW axial traces were developed during the second deformation (~1600 Ma), which was also associated with granulite facies metamorphism and development of grey gneisses, Tirodi Gneiss—III, during the second cycle of the Satpura orogeny. The Tirodi Gneiss—IV (~1450 Ma) were developed during the waning phase of the Satpura orogeny. Low intensity deformation in CITZ marked by open folds with ~NS axial traces and thermal event (~950 Ma) were possibly related to the amalgamation of India and Australia to form East Gondwana along ~NS trending Pinjarra Orogen (~1100–900 Ma) on the western margin of Western Australia.