Palaeoproterozoic (∼1.9Ga) extension and breakup along the eastern margin of the Eastern Dharwar Craton, SE India: New Sm–Nd isochron age constraints from anorogenic mafic magmatism in the Neoarchean Nellore greenstone belt

Dismembered ophiolites in Paleoproterozoic nappe complexes of Kandra and Gurramkonda, South India

“…We also provide some of our preliminary results on the geochemistry of the Kandra rocks to supplement earlier published results (e.g. Ravikant, 2010;Vijaya Kumar et al, 2010) to further elucidate the tectonic setting.…”

“…The Nellore schist belt (NSB) in South India consists of metamorphosed and migmatitized volcano-sedimentary rocks with intrusive granites and pegmatites, ranging in age from Neoarchean to late Proterozoic (Babu, 1998(Babu, , 2001Dobmeier et al, 2006;Ghosh et al, 1994;Gupta et al, 1984;Ramam and Murty, 1997;Ravikant, 2010;Vijaya Kumar et al, 2010). The NSB is sandwiched between the high grade Eastern Ghats belt (EGB) and the Nallamalai fold belt (NFB) bordering the Eastern Dharwar craton (Fig.…”

Inversion of calcite twin data, paleostress reconstruction and multiphase weak deformation in cratonic interior – Evidence from the Proterozoic Cuddapah basin, India

“…These rock units include contemporaneous mafic to ultramafic dykes and sills of~1900 Ma age (Bhaskar Rao et al, 1995;French et al, 2008), connected to thermal perturbations and basin opening in the Eastern Dharwar craton (Drury, 1984;Bhattacharji and Singh, 1984;Nagaraja Rao et al, 1987;Dasgupta et al, 2005;Ravikant, 2010). The unconformably overlying Kurnool Group, which are devoid of such mafic igneous intrusive is understood to have been deposited during the Neoproterozoic.…”

“…Several authors in recent years have suggested the possibility of more than one cycle of Proterozoic rifting, opening of sea and later convergence from records in the southern part of the Eastern Ghats, Prakasam alkaline province, Nellore-Khammam schist belt (NSB) and the Nallamalai fold belt (NFB), as well as those from the intracratonic basins further west of the EGB and other fold-and-thrust belts (Saha, 2004;Leelanandam et al, 2006;Vijaya Kumar and Leelanandam, 2008;Saha et al, 2010;Ravikant, 2010;Henderson et al, 2014;Saha and Patranabis-Deb, 2014;Saha et al, 2015). Although, the high grade terrains of the Eastern Ghats and adjoining fold-andthrust belts are important in linking India with other Gondwana fragments in the Proterozoic, the intracratonic basins provide important clues in sea level fluctuations which may be influenced (Tripathy and Saha, 2013).…”

The Chimalpahad anorthosite Complex and associated basaltic amphibolites, Nellore Schist Belt, India: Magma chamber and roof of a Proterozoic island arc

“…Sr isotopic analyses of the whole rocks were carried out at the Geochronology Laboratory of the Geological Survey of India, Kolkata, following the procedures of Ravikant (2006), with a TaF5 activator and 1_l AG 50 W Â 8, 200-400 mesh. Detailed descriptions of analytical procedure used for Sm-Nd geochronology are given in Ravikant (2010). Sm-Nd isotopic compositions and elemental abundances (ID-TIMS) are listed in Table 3.…”