PALEOMAGNETIC ANALYSIS OF THE NEWER DOLERITE DYKE SWARM IN THE SINGHBHUM CRATON OF PROTEROZOIC INDIA

Peninsular India is one of the major constituents in the Precambrian supercontinents Columbia and Rodinia. Although much improvement has been made in recent years, many Precambrian reconstructions are lacking high resolution paleomagnetic data with good geochronologic control including those from India. India is divided into two regions, consisting of five cratons; the North India Block (NIB) consists of the Aravalli-Bundlekhand craton and Vindhyan Basin and the South India Block (SIB) consists of the Singhbhum, Dharwar, and Bastar cratons. The basement rocks of the Singhbhum craton are subdivided into three groups: the Older Metamorphic Group (OMG; 3.6-3.5, 3.4 and 3.2 Ga), the Iron Ore Group (IOG; ~3.5Ga), and Singhbhum and related granites (3 to 3.1Ga; see Meert and Pandit, 2015 and sources within). The mafic dyke swarm being analyzed in this study is commonly referred to as the Newer Dolerites and trend NW/SE and NNE/SSW with a crosscutting relationship. This dyke swarm intrudes all previously mentioned regional basement rocks (Meert and Pandit, 2015). Recently, Shankar et al. (2014) published precise Pb-Pb ages of 1766.2+1.1 Ma and 1764.5+0.9 Ma on two NW/SE oriented dykes. Ages for some of the other dyke swarms in the Singhbhum craton are poorly constrained (e.g. Bose, 2008). Pilot studies show at least three well-defined directions that show some similarity with paleomagnetic data from the Dharwar craton (Belica et al., 2014). On a small-scale, the amalgamation of the North and South blocks are important for India’s history. We can then use this information to gain insight into the overarching amalgamation of India within the Columbia and Rodinia formations. We will be presenting paleomagnetic data from the Singhbhum craton dykes in these two contexts.