--> Abstract: Devonian and Carboniferous Carbonate Platforms in the Karatau of S. Kazakstan: Outcrop Analogs for Coeval Carbonate Reservoirs in the N. Caspian Basin, by H. E. Cook, V. G. Zhemchuzhnikov, W. G. Zempolich, V. Y. Zhaimina, P. J. Lehmann, PH. A. Lapointe, and V. M. Buvtyshkin; #90942 (1997).

Datapages, Inc.Print this page

Abstract: Devonian and Carboniferous Carbonate Platforms in the Karatau of S. Kazakstan: Outcrop Analogs for Coeval Carbonate Reservoirs in the N. Caspian Basin

COOK, H. E., USGS; V. G. ZHEMCHUZHNIKOV; W. G. ZEMPOLICH; V. YA. ZHAIMINA; P. J. LEHMANN; PH. A. LAPOINTE; V. M. BUVTYSHKIN

4,500 m-thick Devonian and Carboniferous carbonate platform facies in the Karatau are analogs for coeval oil and gas fields in the N. Caspian Basin. Relative sealevel changes evidenced throughout the section were responsible for platform margin drowning and backstepping, multiple stacked sequence sets in platform interiors, paleosols and karsting. 1) Frasnian and Famennian (~1,500 m) platforms are reef-rimmed algal-stromatoporoid calcisponge boundstone and rudstone; platform interiors contain mud-mounds (10-100 m), carbonate sands, cryptalgal laminites, evaporitic laminites and a 90 m-thick regionally extensive collapse and karst breccia. Basin margins contain carbonate turbidites and debris flow aprons. 2) Tournasian carbonates (~1,000 m) form ramps of brachiopod-crinoid biostromes; ramp interiors have abundant tidal fiat facies; seaward ramp settings contain mud mounds (100-200 m) and bioclastic turbidite aprons. 3) Visean and Serpukhovian platforms (~1,500 m) consist of slope mounds and grainstone-rimmed margins. Mounds consist of sponge-bryozoan-Tubiphytes-algae boundstone and cementstone (~100-500 m) with some mounds being interbedded with carbonate turbidite aprons. Grainstone-rimmed platform margins are characterized by cross-bedded ooid-bioclastic sands, and platform interiors contain ooid, bioclastic and phylloid algae sands and muddy facies. (4) Bashkirian carbonates contain slope mounds of algae-brachiopod boundstone and cementstone (~500 m) and platform margins and interiors of ooid, bioclastic and phylloid algae sands.

Numerous exposure surfaces occur throughout the section with paleosols being common in the Visean through Bashkirian. Thick stacks of upward-shallowing cycles comprised of dolomitized and karsted platform margin and platform interior ooid-bioclastic sands form potential reservoirs whereas upper slope mounds contain abundant marine cement and are relatively tight. These geometric and diagenetic patterns are analogous to some reservoirs in the N. Caspian Basin such as in the Karachaganak and Tengiz fields.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria