Sedimentology of the NW margin of the Arabian plate and the SW–NE trending Nahr El-Kabir half-graben in northern Syria during the latest Cretaceous and Cenozoic

The Late Cretaceous (Maastrichtian) to Recent sedimentary record of NW Syria documents the palaeoenvironments and regional tectonic setting during a time when the Neotethys ocean to the north was closing, culminating in regional collision by mid-Miocene time. This detailed sedimentological study builds on a biostratigraphical framework established by Russian workers. During the mid-Maastrichtian the Baer-Bassit ophiolite and related melange were emplaced southwards from Neotethys onto the northern margin of the Arabian (African) plate, resulting in flexurally controlled deepening to the south. After short-lived emergence and erosion of emplaced units a renewed marine transgression ushered in shelf-depth, open-marine carbonate deposition during the Palaeocene–early Eocene. This deposition was characterized by generally westward-channelised mass flow from shallow-marine carbonate banks to the east, probably influenced by storm conditions. Flexurally controlled uplift and erosion took place during late Eocene–Oligocene, related to final closure of Neotethys. Shelf-depth carbonate deposition resumed during the Aquitanian (early Miocene), influenced by tectonic subsidence. During the Burdigalian, a SW–NE trending, narrow (up to 15 km wide), linear (∼ 60 km long) basin developed in the vicinity of the present-day Nahr-El Kabir river valley. This basin is attributed to extension or transtension along the Nahr El-Kabir Fault. This important lineament runs onshore from the southern limit of the Cyprus arc (Tartous Ridge), through NW Syria. It is then offset by the Dead Sea Transform in the Ghab Valley, before merging with the South Anatolian Transform Fault in Turkey further northeast. The basin in NW Syria developed into the asymmetrical Nahr El-Kabir half-graben during the mid-Miocene with uplift of the northern margin and rapid fault-controlled subsidence of the basin axis. Large volumes of terrigenous clastic and shallow-marine bioclastic material were redeposited from the flanks into the axis of the basin, mainly as gravity flows. Shelf-depth carbonate deposition characterized both basin flanks, especially the southern margin. Regression culminated in gypsum and marl precipitation in tectonically active local depocentres during the Messinian salinity crisis. Pliocene re-flooding established argillaceous shelf deposition within and around the pre-existing basin, coupled with local alkaline basalt volcanism and faulting in the southern, coastal area. Regional regression gave rise to prominently channelised bioclastic sedimentation by the late Pliocene. The Quaternary was marked by regional uplift and terracing, influenced by glacio-eustatic sea level change, climatic change and further movement along the Nahr El-Kabir Fault. The dominant control on basin development was thus local tectonics related to movements along the El-Kabir lineament and its interaction with regional-scale tectonic events, while eustasy played a subsidiary, modifying role.