A palaeomagnetic approach to the origin of the Black Sea

SUMMARY Available palaeomagnetic data for the circum‐Black Sea region are reviewed with the object of evaluating the geodynamical evolution of the Black Sea. Jurassic data from the south of the Stara planina‐Forebalkan zone (south of the Moesian platform) in Bulgaria, which was then part of the east European platform, place the region at about 39° latitude; while the Pontides, the northernmost tectonic unit of Turkey, were at a lower latitude (10‐15°). Palaeomagnetic investigations on Upper Cretaceous magmatic rocks sampled in different part of the Srednogorie tectonic unit (southern boundary of the Stara planina‐Forebalkan) indicate that the region was at 39° palaeolatitude during the Upper Cretaceous, while the Pontides had moved northward to 23° palaeolatitude since Early Cretaceous time. The Great Caucasus domain of the USSR was welded to Eurasia by Coniacian time and had a palaeolatitude of 36°. Calculated palaeopole positions for the above‐mentioned geological times for the Pontides fit well with the African palaepoles but largely deviate from the Eurasian ones. Taken together, these observations indicate that the Pontides were not part of Eurasia; instead, they were separated from the east European platform by the early Mesozoic Tethys. This conclusion does not favour the rifted ‘back‐arc’ hypothesis for the formation of the Black Sea during Cretaceous time, as suggested by some researchers (Adamia et al. 1977, Hsü et al. 1977, Sengör & Yilmaz 1981).