Tectonomagmatic evolution of Khairagarh Group in Sitagota syncline, Dongargarh Supergroup, Bastar Craton: Insight into Paleoproterozoic crust mantle processes

Abstract

This contribution presents for the first time a digital elevation map and 1:50,000 scale geological map of Sitagota syncline, Khairagarh Group, which is spread in around 1000 km² area in the north Bastar Craton (survey of India toposheets 64 C/11 and C/15). We report for the first time, exposures of Algoma-type banded iron formation, intertrappean shale, and oxide and sulphide mineralization in Mangikhuta basalt. Mafic enclaves are reported in the Dongargarh granite. Geochemistry and petrogenetic study of Mangikhuta and Kotima volcanics of Khairagarh Group is presented. Although field investigation and digital elevation map reveal Khairagarh volcano-sedimentary sequence underwent more than one phase of orogeny, the ubiquitous presence of very low-grade metamorphic mineral assemblages in volcanic rocks indicates they did not undergo high P–T transformation and most of the alteration and metamorphism took place at near-surface conditions. Our tectonomagmatic model proposes the occurrence of a rift basin in the north Bastar Craton from 2.46 to 2.2 Ga, resulting in sedimentation and high-Mg basalt to basaltic-andesite magmatism. The genesis of Sitagota syncline is attributed to closure and deformation of this rift basin due to compressive forces, probably related to Paleoproterozoic Dongargarh Kotri mobile belt and Mesoproterozoic central Indian tectonic zone. Tectonomagmatic and geochronological similarity of Khairagarh Group to Lower Wyloo Group of Ashburton basin in Pilbara Craton and Hekpoort and Ongeluk basalt formations of Transvaal basin in Kaapvaal Craton indicates Bastar Craton was part of Vaalbara supercontinent in Paleoproterozoic times.