Structure Of The Offshore Obducted Oman Margin: Emplacement Of Semail Ophiolite And Role Of Tectonic Inheritance

The northern Oman margin is a key area for understanding the emplacement of the Semail Ophiolite and obduction processes in general. This study uses a grid of 2D-multichannel seismic lines tied to well data to characterize the offshore domain of the Semail Ophiolite and reappraises the obduction and post-obduction history of the Oman margin. West of Muscat, in the Sohar basin, the late Cretaceous to Paleogene tectonic mega-sequence records syn- to late-obduction stages and the deposition of erosional products of the autochthonous Arabian sediments, including a major mass transport complex. Syn-obduction thrusting is documented in this sector only, as a major fault emplacing a distal basement high (likely volcanic) onto Campanian sediments over >10 km. To the east, the Hatat and Tiwi basins are characterized by a less-copious Maastrichtian-Paleogene sequence. These basins developed above a domain characterized by the northern equivalent of the Saih Hatat dome and later extensional faults. This sector distinctively records the extensional phase associated with the exhumation and erosion of the subducted continental margin. The dichotomy between the two sectors is linked due to a structural high located offshore, in the continuation of the Semail Gap transfer fault. We propose that this transfer fault, coincident with a major Pan-African structure, affected the architecture of the passive margin during both rifting of the Neotethys and later ophiolite emplacement, that is, during (continental) subduction and obduction.