Igneous rock associations 5 – Oceanic island volcanism II: mantle processes

Oceanic island basalts (OIBs) have been central to understanding evolution of the Earth and mantle because their iso-lated positions in ocean basins limit the potential for magma contamination by continental crust. Melting processes (e.g., percentage melting) affect OIB chem-istry but isotopic and trace-element ratios provide information on mantle-source compositions. They indicate that OIB mantle sources represent mixtures between mid-ocean ridge basalt (MORB) mantle and four other mantle compo