The northeast part of the Black Sea consists tectonically of the Kerchi-Taman downwarp, the Mountainous Crimea, and the north part of the Trans-Caucasus microplate. The Kerchi-Taman downwarp extends some 100 km in an east-west direction and is immediately south of Kerchi Strait, which joins the Black Sea and Sea of Azov. This feature is the offshore continuation of the Greater Caucasus mega-anticlinorium. In its eastern part is first the Anapa high and then to its east and extending onshore is the Novorossiy-Lazarev mega- synclinorium. To the west of Kerchi-Taman downwarp is the Mountainous Crimea and on its south is the Trans-Caucasus microplate. The boundary with the Indolo-Kuban downwarp on the north is placed provisionally along an east-west fault some 6-8 km south of Kerchi Strait.
The region has complex geology. The section consists of Neogene- Quaternary sediments, clastics (largely clays) of the Oligocene-Miocene (Maykop), flysch of the Eocene-Upper Cretaceous, clastics of the Lower Cretaceous, and possibly carbonates of the Lower Cretaceous and Upper Jurassic. This geology is based largely on seismic studies and correlations with onshore deep-drilling data. One offshore well (Rifovaya 320) has been drilled on the shelf. It bottomed at 2000 m still in Maykop.
Beginning in 1976 a large volume of seismic surveying was accomplished in the Kerchi-Taman downwarp. This elucidated the structure of the Neogene-Oligocene part of the section. Subsequent work yielded information on the Eocene-Upper Cretaceous but no information on the Lower Cretaceous and older rocks. Seismic profiles were run on the sedimentary units of the Mountainous Crimea (Feodosiy high) in the Eighties.
Seismic surveys indicate that the upper part of the sedimentary cover of Kerchi-Taman downwarp consists of Oligocene-Miocene and upper Miocene-Pliocene sediments. A system of linear anticlines in the Maykop might be takes as diapiric; however, gravity surveys indicate that no diapirism has taken place. Reinterpretation of 14,000 km of seismic lines has allowed compilation of a structure map of the entire offshore shelf for the top of the Eocene-Upper Cretaceous complex. Diapiric and crypto-diapiric folds correspond with negative gravity anomalies.
The main oil-gas prospects for Kerchi-Taman downwarp are
Samartian and Karagan-Chokrak beds at crests of small anticlines.
Only small pools are predicted. Anapa high is a very favorable sector
of the shelf owing to high content of sands in the Maykop. Medium-
size pools (more than 10 MM tons oil equivalent) may be present
on anticlines. In the Trans-Caucasus microplate of the deep-water
depression of the Black Sea large domal traps are predicted for
the Eocene-Upper Cretaceous of the North Black Sea mega-high.
Anomalous objects are identified in the underlying Upper Jurassic-
Lower Cretaceous. These are probably carbonate massifs and
may contain gigantic oil accumulations. Taken from Popovich (2000);
digested in Petroleum Geology, vol. 35, no. 3, one structure map,
in preparation.
Copyright 2001 James Clarke. You are encouraged to print out this
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