High-potassium granites in the Masirah ophiolite of Oman

Abstract

SummaryMasirah Island lies off the SE coast of Oman and comprises a fully developed, though tectonically disturbed ophiolite, unconformably overlain by early Tertiary limestone. The ophiolite consists of harzburgites, cumulate gabbros, a sheeted dyke complex, and pillow lavas with sediment intercalations. Within the ophiolite occur granites the geochemistry of which, particularly their high K2O and Rb, and low Zr and Zr/Nb, ismore typical of a continental crust environment and suggests that at the time of their formation continental crust existed beneath or immediately W ofthe Masirah Ophiolite.