Timing of opening of the Black Sea basin

Abstract

A detailed study of the Mesozoic palaeogeographic evolution of the Rhodope-Pontide fragment and the region surrounding the Black Sea as a whole shows that the Black Sea basin began opening as a back-arc basin by the rifting of a young continental margin magmatic arc during Aptian-Cenomanian time. During the early Cretaceous the present Black Sea region was occupied by an extensive, generally south-sloping, shallow, carbonate-dominated shelf developed in the late Jurassic along the south-facing Atlantic-type continental margin of Eurasia north of the Neo-Tethys. Following the onset of subduction-related volcanism on the Rhodope-Pontide fragment in the Aptian-Albian, disintegration of this shelf started in the Western Pontides and in the Moesic platform. Block-faulting and accompanying subsidence accelerated in the Cenomanian and in a number of places (e.g. the Rhodope-Pontide fragment, Pre-Caucasus, Crimea, Moldavia) caused the formation of large depressions or basins on the subsided blocks with deposition of deeper water sediments locally intercalated with volcanics. This Cenomanian disintegration, which began tearing the Rhodope-Pontide fragment from the main Eurasian continental block along the young volcanic axis of the south-facing Neo-Tethyan magmatic arc, is here interpreted as the initial rifting and opening of the Black Sea basin, which underwent a uniform, probably thermally-induced, subsidence later in the Senonian. Data from the circum-Black Sea region show that the Black Sea basin is unrelated to the basin opening and closing events in the Caucasus and in the Balkans that occurred in the Jurassic to early Cretaceous.