Trace and rare earth element geochemistry of clinopyroxene in mafic dykes from Western Dharwar craton, southern India

Abstract

The major and trace element characteristics of the clinopyroxene from two generations of dykes, dolerite and olivine dolerite dykes of Western Dharwar Craton were investigated by using electron microprobe and LA–ICPMS. The clinopyroxene in dolerite dykes show a compositional zoning with Mg# decreasing from the core to the rim (85 to 51) and Cr₂O₃ contents decrease towards the rim. The trace and rare earth element (REE) pattern of the core shows lower concentrations of REEs compared to the rim. The clinopyroxene in the olivine dolerites are devoid of zoning and compositionally more primitive than the dolerites as visible in the trace element and REE concentrations. The dolerite and olivine dolerite are formed from different source magmas and the fractional crystallization of clinopyroxene is dominant in dolerites. The present estimated melt composition in equilibrium with clinopyroxene is consistent with the bulk rock composition for dolerite and olivine dolerite.