Tectonothermal events in Central Indian Tectonic Zone (CITZ) and its implications in Rodinian crustal assembly

Abstract

The Precambrian crust of Central India comprising Bundelkhand Craton (BKC) in the north and Bastar Craton (BC) in the south were accreted along a ENE–WSW trending Proterozoic Central Indian Tectonic Zone (CITZ). The CITZ is an ensemble of several low- to medium-grade supracrustal belts, gneisses, granitoids and a few linear tracts of granulite belts. A number of crustal scale shear zones define the boundaries of the supracrustal belts and discrete terrains. Available data suggest polyphase tectonothermal events in CITZ, spanning from Palaeoproterozoic to early Neoproterozoic. Each event is characterized by contractional tectonic regime and attendant metamorphism and magmatism. A new plate tectonic model, in contrast to the earlier one of Yedekar et al. [Geol. Surv. India Spec. Publ. 28 (1990) ], is proposed. According to the present model a northward dipping subduction system leading to continent–continent collision explains the growth and assembly of the CITZ. The continent–continent collision is tentatively placed at ca. 1.5 Ga, which is comparable to similar tectonothermal event in Chotanagpur Gneissic Complex further east. While the suturing event predates the global Grenvillian Orogeny (∼ca. 1.3–1.0 Ga), the Sausar tectonothermal event (ca. 1.1–0.9 Ga) of CITZ is correlatable with the latter.

Introduction

It is well known that a supercontinent called Rodinia, which apparently contained all continental blocks, existed at ∼1 Ga (Dalziel, 1991, Hoffman, 1991, Moores, 1991). It is presumed that Rodinia was formed largely by accretion of various continental blocks during Grenvillian/Circum East Antarctica (CEA) Orogeny (ca. 1.3–1.0 Ga) (Rogers, 1996, Yoshida et al., 2000, Condie, 2003). In general, these orogenic/mobile belts are characterized by amalgamation of various components, which record several episodes of Pre-Grenvillian tectonothermal events. Thus, it is essential to study different components and imprints of complex tectonothermal histories of a mobile belt in order to build coherent regional scale tectonic models. Although the applicability of the plate tectonic models to the Precambrian terranes is questioned by few workers (e.g. Hamilton, 1998, Perchuk et al., 2001 and references therein), such models are widely used and excellently demonstrated in many of the Archaean–Proterozoic mobile belts (e.g. Windley, 1995, Condie and Solan, 1998, de Wit, 1998, Chadwick et al., 2000).

The Peninsular shield of India is composed of several Archaean cratons bordered/separated by Proterozoic mobile belts (Fig. 1, inset). Eastern Ghat Mobile Belt (EGMB), Delhi–Aravalli Mobile Belt, Singbhum Mobile Belt and Central Indian Tectonic Zone (CITZ) are some of the prominent mobile belts. Among them, a considerable amount of work has been carried on EGMB, which revealed the polycyclic tectonothermal evolution of the belt (Dasgupta, 1998, Dasgupta and Sengupta, 2000, Yoshida et al., 2000). Further, continuation of EGMB in to the adjoining east Gondwanaland has been demonstrated. In comparison, the CITZ has received little attention in 1980s, barring a few publications on the geological aspects of different lithotectonic units (Roy and Bandyopadhyay, 1990, Jain et al., 1991, Bandyopadhyay et al., 1995). Yedekar et al. (1990) provided the plate tectonic model for the evolution of the CITZ, which was refuted by later workers (Bhowmik et al., 1999, Acharyya and Roy, 2000, Roy et al., 2000). Recognition of ca. 1.0 Ga event from Sausar supracrustal belt (Lippolt and Hautmann, 1994) and collision-related high-pressure granulite belt (Bhowmik et al., 1999, Bhowmik et al., 2000), provided major impetus for detailed studies on CITZ in the perspective of the Rodinian Assembly (Acharyya, 2001, Acharyya and Roy, 2000, Bhowmik et al., 2000, Roy et al., 2000, Roy et al., 2001, Roy and Hanuma Prasad, 2001a). Here we present a brief review of the studies carried out so far and enumerate a plate tectonic model for the evolution of CITZ.