Petrochemical studies on trap rocks around tandur, Andhra Pradesh, India

Abstract

The basalts of Tandur and adjoining areas in Andhra Pradesh are olivinefree tholeiites. Major element abundances in thirty samples indicate that these basalts are poorer in silica and richer in iron, magnesium, phosphorous and titanium relative to the normal basalts. The high Fe2O3/FeO ratio (1.07) could mean either that the traps were extruded under oxidising conditions or that the magma held excess amount of water. The relative enrichment of iron and depletion of silica in the Tandur basalts may have been controlled by the partial pressure of oxygen, presence of significant amounts of water, depth of generation of source magma etc.