--> Abstract: Upper Jurassic Reefs of the Western Caucasus-Crimea; Hydrocarbon Implications for the Eastern Black Sea, by Li Guo, Stephen J. Vincent, Samuel P. Rice, and Vladimir Lavrishchev; #90072 (2007)

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Upper Jurassic Reefs of the Western Caucasus-Crimea; Hydrocarbon Implications for the Eastern Black Sea

Li Guo1, Stephen J. Vincent1, Samuel P. Rice1, and Vladimir Lavrishchev2
1University of Cambridge, Cambridge, United Kingdom
2Kavkazgeols'emka, Yessentuki, Russia

Widespread Upper Jurassic reefs are important potential reservoir facies in the Eastern Black Sea Basin. Russian seismic reflection data from the northern Shatskiy Ridge indicate possible offshore reef-facies occurrences up to 1-2 km thick and 10-20 km wide. Data from excellent onshore exposures in the Russian Western Caucasus and Crimea provide a reservoir analogue for offshore targets. A model for development and distribution of the carbonate reefs is presented with reference to possible alternative tectonic settings for the Upper Jurassic north Tethyan Margin.
Outcrops of well-preserved Upper Jurassic reefs can be grouped into coral-dominated, siliceous sponge-microbial and microbial types. Patchy and massive coral-dominated reefs formed at shallow-water platform margins or in slightly restricted deeper-water mid shelf settings. Siliceous sponge-microbial and microbial reefs occur as lenses and mounds and are restricted to deeper-water mid-outer shelf environments. The development of these reefs was controlled mainly by local variations in water depth, light, and the availability of nutrients.
The reefs exhibit a complex pattern of porosity development reflecting independent diagenetic histories involving near-surface and deep-burial dissolution, dolomitization and dedolomitization. Porosity is particularly common in coral-dominated reef facies and consists of both primary and secondary types.
Coral-dominated reefs analogous to onshore outcrops in the Russian Western Caucasus are likely to occur along the northwestern margin of the Yuzhnyi-Adler carbonate platform in the Eastern Black Sea. Possible isolated deeper-water reefs imaged on the northern Shatskiy Ridge could be largely composed of siliceous sponge-microbialite and microbialite facies. Similar reef facies may be present on the Mid Black Sea High.

 

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