A chromitite-dunite-orthopyroxenite field association in the Wadi Rajmi (northern Oman Ophiolite): Possible implications on the relative timing of komatiitic and boninitic melt occurrences

Abstract

In the northern Oman ophiolile mantle section, an orthopyroxenite veinlet within a komatiitic dunite has been found. It exhibits a relatively high-Mg character. Whether this orthopyroxenite represents the final product of differentiation of the komatiitc melt involved in the dunites genesis, or it is of a boninitic affinity, as those already reported. In this second case, it may implicate that the komatiitic melt activity occurred during the Oman ophiolite obduction in between two boninitic melt episodes; the predating one being responsible for the genesis of the chromitite pod and, the postdating one, being responsible for that of the orthopyroxenite.