Early Mesozoic History of the Black Sea-Caucasus Area

Vladimir G. Kazmin

Marginal basins with ocean crust existed in the Black Sea area in Triassic time behind a volcanic arc built on top of the Hercynian basement of Pontides. The eastern extension of the arc was in the fore-Caucasus. Triassic sediments and volcanics, formed in forearc basins, can be traced from the southern slope of the Great Caucasus (Svanetia) to the Karakaya belt of Turkey. These sediments were deformed at the end of the Triassic when terranes derived from Gondwana collided with the active margin of Paleotethys. In Svanetia a succession of middle Paleozoic clastics (the Dizi series) deposited at the base of the north-facing continental slope, presumably on the passive margin of Gondwana. The Dizi series is either an independent terrane or forms a western extension of Iran, which collided with Eurasia at the same time. Displacement of the subduction zone to the south of the accreted terranes was accompanied by a major episode of extension on the active margin in Early Jurassic time; the marginal sea of the Great Caucasus and the intra-Pontide basin in Turkey were opened. In the late Middle Jurassic, Pontides collided with Crimea, closing the Triassic proto-Black Sea. Immediately after collision, continental rifting commenced, once again separating Pontides from Eurasia and manifesting the birth of the Black Sea basin. Oceanic crust began to grow in the latter in Senonian time.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.