Nd-Sr isotopic and trace element characteristics of low Ti-P-K basalts from the Mahakoshal greenstone belt, central India

Continental rift zones are long, narrow tectonic depressions in the earth's surface where the lithosphere has been modified by extension. The dynamics and evolution of rift zones has been the subject of intense study and debate for many years and still remains the focus of active investigation. Magmatism in the rift zones has important implications for crustal and mantle evolutionary models. The late Archean-Paleoproterozoic Mahakoshal greenstone belt (MGB) is a 500 km long, 5 to 40 km wide, ENE-trending rift zone in central India. The MGB is an intracontinental mantle-activated aborted rift filled with a thick volcano-sedimentary sequence metamorphosed to the greenschist facies. The rocks have undergone polyphase deformation and are traversed by ENE-trending thrust faults and minor north striking, high-angle normal faults. The geology, metamorphism and structural setting of the MGB are detailed in some previous studies (Roy & Bandyopadhyay 1990, Roy et al. 2002, Nair et al. 1995, Talusani 2001), but limited information exists on the geochemistry of magmatic rocks of the MGB. For this reason, geochemistry of the basalts of the MGB has been investigated.