Using Strontium Isotope Stratigraphy and subsidence modelling to infer the timing of rift events in the Black Sea region

In this presentation, we will show how the analysis of stratigraphic records in the eastern Pontides, Turkey, and the western Greater Caucasus, Russia, can be used to help constrain the timing of tectonic events in the intervening Black Sea. More specifically, strontium isotope stratigraphy and foraminiferal biostratigraphy carried out on the carbonate Berdiga Formation at the Kiraoca section in the Eastern Pontides has identified significant hiatuses during the latest Kimmeridgian to Tithonian or Berriasian, and during the Hauterivian to Barremian (Fig. 1a). Broadly contemporaneous stratigraphic gaps in multiple successions around the Black Sea provide additional insights and point to a regional driving mechanism (Fig. 1). The timing of these hiatuses does not correspond to periods of eustatic lowstand. However, it does broadly coincide with two phases of increased subsidence in the Greater Caucasus Basin near Sochi, Russia, following initial Aalenian to Bajocian basin formation. These subsidence phases occurred during the late Tithonian to Berriasian and Hauterivian to early Aptian. Thus, it is possible that subaerial exposure and hiatus formation in the Eastern Pontides was caused by rift flank uplift during periods of regional extension. We speculate that these phases of regional extension are likely to have affected the intervening Black Sea region and that this may help constrain initial rifting within the western, and possibly eastern, Black Sea basins to the ?latest Jurassic to Early Cretaceous. This is consistent with region al seismic data from the Black Sea.