Geochemical Evidences for Possible Absence of Cu-Sulfide Deposits in the Deccan Volcanic Province, India

Abstract

Continental flood basalt provinces (CFBs) are important hosts for large-scale Cu-sulfide deposits. However, sulfide mineralization is yet to be discovered, if any, in the end-Cretaceous Deccan volcanic province, India. In the present study, geochemical evidences for the possible absence of Cu-sulfide deposits associated with the Deccan basalts by analyzing and comparing the geochemistries of the Deccan and Siberian CFBs are provided. The Fe-rich nature and high fO2 conditions did not favour sulfide saturation at any stage of magma evolution in the Deccan province. Crustal contamination of the Deccan magmas also did not increase the sulfur budget. The most contaminated basalts of Bushe and Poladpur formations of the Deccan province do not show any depletion in the copper contents compared to other formations. In the absence of sulfide saturation, copper behaved as an incompatible element in the Deccan magmas in contrast to the Siberian basalts, in which copper behaved as a compatible element during magma evolution due to sulfide saturation consequently formed world-class copper sulfide deposits. It is demonstrated that the lithosphere- and asthenosphere-derived Deccan magmas have similar Cu abundances thereby suggesting that the Cu-sulfide deposits associated with the CFBs are process-controlled rather than source-controlled. Although Cu-sulfide deposits may not have formed, the geochemical patterns suggest favourable conditions for native copper mineralization in the Deccan volcanic province. In the present study, a set of geochemical proxies that can be utilized as preliminary exploration tools for Cu-sulfide mineralization in the CFBs is proposed.