Tectonic Evolution of the Black Sea Orogene Belt and the History of Opening of the Black Sea Basin

Sener Usumezsoy

The Black Sea basin is surrounded by successive orogenic belts of Hercynian, Cimmerian, and Alpine ages. The Rhodope, Thracian, western Pontian, and Transcaucasian (RTPT) blocks of Precambrian age were involved by the circum-Black Sea orogene belts.

The Hercynian orogene was documented in the Balkanide, Great Caucasian, Kriastide, southern Pontian, and Transcaucasian belts. These belts diverged into northern and southern belts. The northern belt extended along the Balkanide and Great Caucasian north of the RTPT blocks. The southern Hercynian orogene extended along the Kriastide belt. The southern Pontian and Transcaucasian belts were located at the southern edge of the RTPT.

The Cimmerian orogene extended north and south of the Black Sea. The southern Cimmerian orogene was represented by the circum-Rhodope and East Thracian-Strandja-Kure belts. The northern Cimmerian orogene belt extended along the Dobruca-Crimean and southern slope belts. The circum-Rhodope belt is located south of the Serbo-Macedonian belt and extends to East Thracian looped orogene and to Strandja orogene.

Following the demise of the Black Sea Cimmerian basin, the northernmost oceanic branch extending from Nish-Trajan through the present Black Sea to the intra-Transcaucasian basin, was opened within the Hercynian and Cimmerian consolidated terrain in the Late Jurassic. The other oceanic branch, extending from Izmir-Ankara through circum Kirsehir to various basins, was opened within the Paleotethyan collision belt, considered to be eastern extension of the Pindus basin. The Nish-Trajan sector of the northernmost basin was closed in the middle Cretaceous, and the Moesian platform re-fused to the Getic-Serbo-Macedonian-Rhodope belt. The easternmost extension of the intra-Transcaucasian basin disappeared in the Late Cretaceous. Consequently, the northernmost oceanic branch was reduced to th present Black Sea basin. The Izmir-Ankara ocean was closed in the Paleocene, but the Tokat-Erzincan ocean was subducted beneath the Pontian continental-margin arc belt in the Eocene, which resulted in the opening of the Adjora-Trealleti basin within the intra-Transcaucasian belt and the spreading of the present Black Sea as a back-arc basin.

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