PALEOMAGNETISM AND GEOCHRONOLOGY IN THE EASTERN DHARWAR CRATON

The study focuses on the acquisition of paleomagnetic directions and ages for thirty-four basaltic dykes in the Hyderabad cluster of the Eastern Dharwar craton, Telangana, India. Previous studies have suggested ages of 1471 +/- 54 Ma for the Hyderabad cluster, as well as affinities to the 2.2 Ga Mahbubnagar swarm, or the Bastar craton’s 1.9 Ga swarm. At least four more distinct dyke ages from Archean to Phanerozoic age have been documented across the entire Dharwar craton. Such intermittent episodes of intrusion, combined with metamorphism and deposition over a long timescale have led to substantial confusion in defining stabilization ages for and relationships between India’s five cratonic nuclei. According to Meert (2015), the Dharwar stabilized by ~2500 Ma, based on intrusion of the Closepet Granite. Sedimentary basin development within the Dharwar began as early as 1880 Ma, based on earliest mafic intrusions. Paleomagnetic directions support a Dharwar and Bastar craton connection by 1880 Ma, but more evidence is necessary to link timing of amalgamation of the Dharwar to the rest of the Southern India Block (SIB) and the entirety of the Indian subcontinent. The goal of this study is to use paleomagnetic and geochronologic data to further constrain the Dharwar cratons role in the region as well as in global plate reconstructions.

Of the thirty-four paleomagnetic sampling sites, eight yielded contact tests, and eight hand samples were collected for chronologic control. E-W and N-S trends dominated, but we note that it is not uncommon to encounter different episodes of dyke intrusions following earlier trends. We present initial results from these dykes along with a review of geochronology in the region.