The Oligocene and Miocene sands in the deep Levant Basin: Provenance and sediment routing

Abstract

The Levant Basin in the Eastern Mediterranean contains a ~3 km-thick, predominantly siliciclastic section of Oligocene-Miocene age, which hosts large hydrocarbon reservoirs (“Tamar Sands Play”). A fundamental question raised with respect to this siliciclastic section concerns its origin and the sedimentary pathways into the deep basin. Here we present an advanced provenance study, including detrital zircon U-Pb-Hf and heavy mineral assemblage investigations, of Oligocene-Miocene siliciclastic sediments retrieved from four boreholes across the Levant Basin. Our investigations reveal a preponderance of Neoproterozoic and older Precambrian zircons with mostly negative εHf values. This U-Pb-Hf pattern indicates that the studied sediments were mainly reworked from Paleozoic-Mesozoic sandstones of Afro-Arabia with variable derivation from the juvenile basement of the Arabian-Nubian Shield. Comparison of the detrital signal in various stratigraphic levels of the Levant Basin shows that Early Oligocene and Early Miocene sand intervals are typified by a large proportion of pre-900 Ma zircons (ca. 50%), by a relatively small proportion of Neoproterozoic zircons with positive εHf values (ca. 25%), and by abundant detrital apatite peloids in the heavy mineral fraction. Resembling Miocene clastic sequences preserved in Israel, these characteristics are taken by us to indicate a dominant provenance in the Arabian side of the Red Sea Rift. On the other hand, Late Oligocene-lowest Early Miocene and Middle-Late Miocene intervals are typified by a mild proportion of pre-900 Ma zircon (ca. 35%) and by a larger proportion of Neoproterozoic zircons with positive εHf values (ca. 35%), they also contain scarce Mesozoic-Cenozoic zircons. These similarities to the Nile Delta sediments are taken by us to indicate a dominant provenance in NE Africa. Overall, our findings suggest that the Levant Basin was fed by varying proportions of sediments derived both from Arabia via the Levant continental margin and from NE Africa via the Nile Delta. While Early Oligocene and Early Miocene sediments, including the main section of the “Tamar Sands”, were chiefly derived from Arabian sources, Late Oligocene-lowest Early Miocene and Middle-Late Miocene sediments mainly sourced from NE Africa. The mere absence of Paleozoic and Mesozoic-aged detrital zircons, abundant in the Eurasian side of the Eastern Mediterranean, suggests that sand sourcing in the overriding plate of the Arabian-Eurasian collision belt did not reach the Levant Basin.