A new perspective of ophiolite studies with special reference to the Oman ophiolite

Abstract

Ophiolite studies seem be now reaching to a turning point. The genesis of ophiolites, classically regarded as ancient oceanic crust and upper mantle, was seriously debated during 1970s since Miyashiro's proposal on the arc origin for the Troodos ophiolite. Since then, many researchers considered that most of ophiolites were generated at supra-subduction zones. Recently two significant findings for the genesis of ophiolites have been carried out. The first is the discovery of MORBs with arc signatures from the Chile Ridge. The second is that MORBs from different oceans have unique features, implying that the source mantles are heterogeneous and have different histories from ocean to ocean. On the other hand, the genesis of the Oman ophiolite, which is the largest and best exposed ophiolite, is still a matter of serious controversy in spite of numerous publications and its well known geological and structural features. There are still many controversial subjects genesis (supra-subduction zone suite or fast-spreading ridge origin), geometry of layering in the layered gabbro (dipping to ridge axis or opposite) and its origin (magmatic or due to deformation), behavior of upwelling mantle (passive or active), emplacement processes and so on. The correlation between volcanic rocks and plutonic rocks is also still confused. We review previous studies on the Oman ophiolite and introduce recent new findings by Japanese geologist team on the Oman ophiolite. Then we discuss on the perspective of ophiolite studies.