Tectonics and magmatism associated with Mesozoic passive continental margin development in the Middle East

Abstract

Early Triassic-Cretaceous rifting and magmatism occurred along the western edge of the Arabian Peninsula from Egypt in the south to Syria in the north, associated with the development of the Neotethyan passive continental margin which is preserved in the present-day Eastern Mediterranean. A change in the direction and rate of extension during the Early Cretaceous had a profound effect upon the developing continental margin and controlled the pattern of rifting, magmatism and sedimentation. Extensive Late Jurassic-Early Cretaceous volcanism occurred throughout the region and is clearly rift-related. Major and trace element (including rare earth element) and Sr–Nd isotopic compositions suggest derivation of the most primitive mafic magmas from an enriched mantle source with minimal evidence of crustal contamination. The magmas appear to have ascended rapidly to the surface through large-scale faults. Isopach maps have been constructed for a series of time intervals during the Mesozoic, using well data from Egypt, Israel, Iraq, Jordan, Lebanon and Syria. These reveal the distribution and orientation of the main depocentres. The main tectonic feature from the Late Triassic until the Late Jurassic was a basin which extended northeastwards from northern Israel to the Palmyrides in central Syria. By the Early Cretaceous, however, deposition switched to a N–S oriented basin in central and northern Israel and Lebanon. The distribution of Late Jurassic-Early Cretaceous magmatism coincides with this new basin and indicates the location of the major extensional fault zones.