From Circum Red Sea Sources to the Levant Basin Sink: An Integrated Provenance Study of Oligocene–Miocene Siliciclastic Sediments From Deep-Sea Boreholes

The Levant Basin of the Eastern Mediterranean accumulated voluminous siliciclastic sediments during the Oligocene–Miocene. The deep-sea section has attracted significant interest as it contains world-class hydrocarbon reservoirs (‘Tamar Sands Play’). Our recent sandstone provenance study revealed that the hydrocarbon-bearing, lower Miocene ‘Tamar Sands’ were recycled from older quartz-rich sandstones that covered the Arabian flank of the Red Sea Rift. However, sandstones constitute just a third of the thickness of the Oligocene–Miocene siliciclastic section in the Levant Basin, with the rest being mainly composed of shales. Unravelling the provenance of the shale fraction is therefore essential for a comprehensive reconstruction of the Oligocene–Miocene source-to-sink system of the Levant Basin. In the present study, we examined the mineralogy and Sr-Nd isotopes of clay samples retrieved from deep-sea boreholes that penetrated the Oligocene–Miocene siliciclastic section. The isotopic composition of most clay fractions resembles that of Nile Delta sediments, indicating that unlike the ‘Tamar Sands’, their dominant provenance lay in NE Africa. Our investigations show that they were derived from Neoproterozoic basement rocks of the Arabian-Nubian Shield and Tertiary continental flood basalts. The absence of chlorite and serpentine negates detrital contribution from the Arabia-Eurasia suture in the north. Compilation of the available thermochronology data and major geologic events shows that the accumulation of the siliciclastic section in the Levant Basin coalesced with uplift of the continental areas around the Red Sea. The marked switch to shale deposition recognised in the basin during the late early Miocene signifies the downfall of the ‘quartzose’ Arabian sediment transport system, when it was partially captured by the evolving Dead Sea Transform valley. Our study highlights the strength of coupling sand and clay provenance investigations in source-to-sink studies of sedimentary basins.