Western Black Sea Onshore: Evolution and Petroleum Potential

Patrick R. Bird, Daniel D. Clark-Lowes, Naci Gorur, Colin More

The western Black Sea onshore area forms part of the Rhodope-Pontide fragment, one of a number of microcontinental plates which collided during the closure of the Neotethys Sea. Integration of seismic, field, and borehole data has established the tectonic evolution of the region and demonstrated its hydrocarbon potential. Since the beginnning of the Jurassic, the area has undergone three major tectonic episodes: (1) late Liassic compression associated with overthrusting of the Istanbul nappe onto the Kure nappe and closure of the Paleotethys Sea; (2) Aptian to Senonian rifting which preceded the opening of the Black Sea north of the area; and (3) late to post-Eocene compression resulting from closure of the Neotethys Sea south of the area.

The Paleozoic and Triassic successions comprise sediments of the Istanbul nappe in the west and metamorphic rocks of the Kure nappe in the east, brought together by closure of the Paleotethys. The Instanbul nappe consists of marine, deltaic, and fluvial sediments, whereas the Kure nappe consists of metamorphosed ophiolites and oceanfloor sediments.

In the Late Jurassic a widespread, uniform sequence of carbonates was deposited. This platform began to break up in the Aptian with the onset of Black Sea rifting. Shallow marine sands of reservoir quality were deposited on relict highs, while organic-rich shales accumulated in subsiding troughs. Continued differential subsidence and turbiditic sedimentation characterized the Late Cretaceous and Eocene, resulting in the burial and subsequent maturation of Paleozoic and Cretaceous source rocks. Late to post-Eocene fold-and-thrust tectonics created the main prospective structures. Preliminary burial history analysis indicates post-tectonic generation and migration. Hydrocarbon plays exist in both the Cretaceous and Paleozoic successions.

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