Crustal configuration of the Dharwar craton, India, based on joint modeling of regional gravity and magnetic data

Abstract

Regional gravity and magnetic investigations were conducted along a 600 km transect across the northern part of the Dharwar craton in the Precambrian Indian peninsular shield from Vasco-da-gama (latitude 15°23′40″N and longitude 73°48′55″E) to Jadcharla (latitude 16°41′40″N and longitude 78°08′18″E). Joint modeling of the two data sets was carried out utilizing GM-SYS (Geosoft) software assuming a four-layer model. A tectonic re-classification of the craton is proposed, prompted by the location of four inferred deep-seated faults, into the western and eastern Dharwar Blocks with an intervening upthrown block. This classification is at variance with the current perceptions of the configuration of the Dharwar craton, some of which hold that the craton consists of only two sub-cratons, an eastern and a western, divided by the Chitradurga thrust fault. However, in the present study, this thrust fault is found to extend no deeper than the basement peninsular gneisses. Furthermore, according to the proposed classification, the thrust fault falls within the intervening block that forms the divide between the sub-units of the craton rather than representing a tectonic boundary. In addition, twenty-six near surface geological members in the region (supracrustals) consisting mainly of schists and younger granites were identified along the transect and modeled for the representative near-surface crustal configuration of the craton.