Using heavy mineral analyses to determine the provenance of Cenozoic siliciclastic depositional systems supplying the northern margin of the Eastern Black Sea

The Eastern Black Sea is one of the few remaining underexplored hydrocarbon basins in Europe. Reservoir quality is a key risk factor in the basin. The analysis of the up-dip portions of Oligocene to Pliocene depositional systems exposed around its northern and eastern margins enable the composition and provenance of sandstones within the basin to be predicted. Quartz-rich sandstones are present, from northwest to southeast, around the Kerch-Taman Strait, along the flanks of the Russian western Greater Caucasus and in western/central Georgia. These are predicted to form better quality reservoirs at shallow and moderate burial depths than their rock fragment-rich counterparts, due to lesser amounts of compactional porosity loss. Heavy mineral analysis has played an important role in determining the provenance of these quartz-rich sandstones. The determination of provenance sensitive heavy mineral ratios, single mineral geochemical analyses and zircon U-Pb SHRIMP ages were particularly informative. Two major sediment source regions for quartz-rich sandstone have been identified: the Russian western Greater Caucasus, which became a subaerial sediment source in the Oligocene, and the East European Craton-Scythian Platform. Oligo-Miocene sandstones from the Russian western Greater Caucasus were deposited as turbidites in the Tuapse Trough. Sandstones from the East European Craton-Scythian Platform were largely trapped within the Indolo-Kuban Basin north of the Greater Caucasus. They only entered the Eastern Black Sea in large volumes from latest Miocene or Pliocene time in the region of the Kerch-Taman shelf at the western tip of the Greater Caucasus. However, it is possible that a precursor to this system supplied the Oligocene to Early Miocene reservoir sandstones within the Subbotina field on the Kerch-Taman shelf. The Dziruli Massif, in western Georgia, also generated quartz-rich sandstones, but these are not thought to have entered the Black Sea.