Constraints on Arabian Plate motion and extensional history of the Red Sea

Abstract

Analysis of the geologic and geophysical data from the western and northern margin of the Arabian plate combined with data from the Red Sea/Gulf of Aden leads to an interpretation of Arabian plate motion that supports an episodic extensional history in the Red Sea and Gulf of Aden. Phase 1 extension began in medial to late Eocene and was caused by the NW propagation of the reoriented Central Indian Ridge spreading center. It stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures. First‐phase extension stopped when the Arabian plate terminally sutured to Eurasia in the medial Miocene and halted northward movement of Arabia relative to Africa. The combined African/Arabian plates moved north more slowly, constricting and thickening continental crust in the Bitlis/Zagros sutures while the Red Sea remained technically quiescent and accumulated salt. By the early Pliocene, continued northward movement was accommodated by lateral extrusion of large continental wedges north of the Bitlis/Zagros sutures. This allowed Arabia to move northward faster than Africa and reopen the Red Sea where phase 2 extension was expressed by seafloor spreading. Extension within the Red Sea/Gulf of Aden rift system has been controlled by the interactions and effects of two factors: (1) convergent processes between the north margin of the Arabian plate and the Eurasian plate to the north and (2) northwest propagation of extension associated with the medial Eocene reorganization of the Central Indian spreading center.