Origin of the Infracambrian Salt Basins of the Middle East

Abstract During the Infra and Lower Cambrain, the Arabian Gulf and Zagros Mountains (Hormuz Formation), South Oman (Ara Formation), Kerman in Central Iran (Ravar Formation), and the Salt Range Province in Pakistan (Salt Range Formation) were all sites of salt precipitation in subsiding rift basins along the Middle Eastern edge of Gondwanaland. Also from 600 to 540 Ma, a rift system extended westwards from the Sinai Peninsula and North Egypt across NE Africa, while a second rift system (about 600 to perhaps 510 Ma) extended northwards from the Sinai Peninsula across the Jordan Valley and Dead Sea into SE Turkey. The development of these rifts was contemporaneous with the left-lateral Najd strike-slip fault system which dislocated the Arabian Peninsula by 300 km. The Najd system may be interpreted as a transform fault system which accommodated rifting between NE Egypt, the Jordan Valley, North Pakistan, Kerman and South Oman. The Najd system is parallel to the Zagros Line, and the latter is also the eastern depositional limit of the Infracambrian Hormuz Formation. The Infracambrian Zagros Line may be interpreted as a right-lateral, strike-slip fault system which caused Infracambrian rifting in the Arabian Gulf and Zagros Mountains. Palaeontological and radiometric age constraints, together with stratigraphic considerations, suggest that the syn-rift evaporites were first precipitated during a transgression which commenced in the Latest Precambrian (600 Ma) and again during a Lower Cambrian regression. The regression terminated a period dominated by marine carbonates and evaporites and initiated the deposition of progradational alluvial to marginal marine sediments. Finally, in the late Lower Cambrian and Middle Cambrian, transgressive marine deposits swept across the Middle East.