Lithostratigraphy of the Upper Jurassic – Cretaceous Deposits and Hydrocarbon Perspective in the Romanian Shelf of the Black Sea

Ovidiu Nicolae Dragastan
Bucharest University, Bucharest, Romania

In the Romanian shelf of the Black Sea (offshore), Petromar Co. drilled and has obtained cores of Middle and Upper Jurassic- Cretaceous deposits, as well as Paleogene and Neogene ones. The Mesozoic and Cenozoic deposits belongs to two main geological units: the North Dobrogea Orogenic Belt and the Moesian Platform. In the offshore of the North Dobrogea Orogenic Belt three cycles of sedimentation have been identified: 1. A lower transgressive cycle corresponding to the compression phase of synrift 1 (Bajocian- Callovian ?), the last stage possible corresponding to a „general” unconformity or to a break up 1 between the Middle and Upper Jurassic , with black calci- and siltic turbidites (Heraclea Formation). 2. A middle transgressive compression phase composed by mudstones, claystones and siltstones ( Pontus Formation), Upper Jurassic- Neocomian in age corresponding to the synrift 2 followed by a break up 2 to the Jurassic-Cretaceous boundary and intra Neocomian covered different times hiatuses. 3. An upper large postrift phase Albian to Senonian, continued during the Paleogene and Neogene. Many short and long time hiatuses are recorded that include the Cretaceous deposits. Three source rocks can be identified for hydrocarbon generation: - the black argillaceous, siltic to sandstones of the Heraclea Formation (Middle Jurassic in age), about 1000 m in thickness.; - the black argillites of the Pontus Formation (Neocomian) and - the Oligocene- Miocene bituminous shales, clays and marls known more or less as the Maikop beds.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece