Research Projects

Alkali basalts are common products of magmatic processes beneath oceanic islands and reflects the complexity of compositions and processes in the Earth's mantle. These oceanic basalts hold key geochemical information, constraints on the genesis of such rocks are critical to understand Earth's interior. Resolving debate regarding the dynamical origin of intraplate basalts requires constraints on the relationship between the compositions of magmas and the temperatures, pressures, and compositions of their sources. Isotope and trace element geochemistry have established that parent lithologies of OIBs in the Earth's mantle are heterogeneous. Previous high-pressure experimental studies have unsuccessful to reproduce major element compositions of alkalic oceanic island basalts (OIB) from partial melts of peridotite±CO2 which suggest pyroxenitic lithology is required in the source of OIB. Evaluation of these possibilities requires new experiments to determine the compositions and proportions of liquids generated during partial melting of pyroxenite+CO2. If alkali basalts originate from partial melting of carbonated pyroxenite, and if the temperature and pressure of melting can be constrained by major element chemistry of plausible parental liquids, the experiments will relate the petrologic character of OIB to the depth of melting and mantle potential temperature in their source. We will address CO2-fluxed pyroxenite partial melts through a series of high-pressure experiments at a range of pressures 1.0-4.0 GPa which covers the range of 30-120 km depth, temperatures (800-1500 oC) in oceanic mantle conditions with varying carbonated pyroxenite compositions. Experiments will be performed in the newly commissioned Experimental Petrology Laboratory in Department of Geology & Geophysics at IIT Kharagpur. Additionally, we would also determine partitioning of trace elements between CO2-fluxed partial melts and pyroxenite residual minerals. In particular, we aim to determine partitioning of first row transition elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, & Zn) and Ga, Ge, as these elements have become important tracers of the source lithologies of oceanic island basalts.