The formation and inversion of the western Greater Caucasus Basin and the uplift of the western Greater Caucasus: Implications for the wider Black Sea region

Abstract

The western Greater Caucasus formed by the tectonic inversion of the western strand of the Greater Caucasus Basin, a Mesozoic rift that opened at the southern margin of Laurasia. Subsidence analysis indicates that the main phase of rifting occurred during the Aalenian to Bajocian synchronous with that in the eastern Alborz and, possibly, the South Caspian Basin. Secondary episodes of subsidence during the late Tithonian to Berriasian and Hauterivian to early Aptian are tentatively linked to initial rifting within the western, and possibly eastern, Black Sea and during the late Campanian to Danian to the opening of the eastern Black Sea. Initial uplift, subaerial exposure, and sediment derivation from the western Greater Caucasus occurred at the Eocene‐Oligocene transition. Oligocene and younger sediments on the southern margin of the former basin were derived from the inverting basin and uplifted parts of its northern margin, indicating that the western Greater Caucasus Basin had closed by this time. A predominance of pollen representing a montane forest environment (dominated by Pinacean pollen) within these sediments suggests that the uplifting Caucasian hinterland had a paleoaltitude of around 2 km from early Oligocene time. The closure of the western Greater Caucasus Basin and significant uplift of the range at approximately 34 Ma is earlier than stated in many studies and needs to be incorporated into geodynamic models for the Arabia‐Eurasia region.

Petroleum geology of the Black Sea: introduction

“…A young age for uplift would limit the amount of clastic (potential reservoir) sediment entering the basin from its margins during the deposition of the Maykop Suite, for example. Seismic data (Afanasenkov et al 2007;Nikishin et al 2010;Mityukov et al 2011) demonstrate thickening of the Maykop Suite into the Tuapse and Indolo-Kuban foreland basins to the south and north of the Greater Caucasus, respectively, supporting the notion of Vincent et al (2016) that the Caucasus were forming during the Oligocene.…”

“…3) (Nikishin et al 2003;Dinu et al 2005;Okay & Nikishin 2015). This was followed by uplift and compressional deformation as strands of Neotethys progressively closed (Allen & Armstrong 2008;Vincent et al 2016).…”

“…Vincent et al (2007Vincent et al ( , 2016) favour a base Oligocene age, based on the onset of massive microfossil reworking and palynological data, indicating palaeoaltitudes of the Greater Caucasus of c. 2 km at this time. Palaeocurrent vectors and heavy mineral compositions also support this notion (Vincent et al 2007), as does some fission-track data (Vincent et al 2013a, b).…”

“…The main phase of the opening of the Eastern Black Sea has been variously interpreted as coeval with the Western Black Sea (Okay et al 1994;Nikishin et al 2003Nikishin et al , 2015aStephenson & Schellart 2010); as late Campanian-Danian (Vincent et al 2016), as Paleocene-Early Eocene (Robinson et al 1995Spadini et al 1996;Shillington et al 2008) or as Eocene (Kazmin Fig. 3.…”

“…Given that the Western Greater Caucasus Basin to the north of the Shatsky Ridge opened in the Early Jurassic as a result of Neotethyan subduction, there may have also been a proto-Eastern Black Sea south of the Shatsky Ridge during the Jurassic, or at least an initial phase of rifting (Vincent et al 2016).…”