Место издания: Florence , Год издания: 2004

The prospecting of hydrocarbons in the west of the Siberian Platform within the Baikit anteclise resulted in the discovery of Riphean section up to 3 km thick. These riphean deposits are composed of carbonate rocks, mainly early diagenetic dolomites including stromatolites, grainstones-packstones, wackestones and mudstones. Laminite forms are prevalent in stromatolites. Columnar stromatolites are rarely observed. Grainstones-packstones dolomites consist of peloids, oolites, pisolites and intraclasts. It was established that the deposition in the studied area chiefly occurred in subtidal or moderately restricted peritidal shelf, which was represented by the complex system of shoals and very shallow depressions between them. Wellsorted oolite-intraclastic grainstones-packstones were deposited on the shoals. Oolite-pisolite-intraclastic packstones and grapestones were formed at the rear parts of bars. Stromatolite laminites, peloid-intraclastic and intraclastic packstones-wackestones, mudstones were deposited in local depressions. Abundant fibrous and tepee structures, fenestrae, predominance of laminites, interbeds of flat-pebbel conglomerates indicate that the carbonate sedimentation occurred mainly in tidal flats. During transgressions peritidal environments were changed into subtidal. Deposition of clayey dolomites and stromatolite conophytoid bindstones was associated with maximum flooding. Micritic-wackestones and mudstones together with argillites and carbonate storm turbidites were deposited in deeper-water (below storm wave basis) shelves. Low-stand episodes were accompanied by progradation of carbonate-siliciclastic tidal flats onto the carbonate shelf. They are recorded by the appearance of quartz sandstones, sandy dolomites and argillites with desiccation cracks on bedding plains. During maximum shoaling siliciclastic material may have been transported from the shelf margin to the deep-sea basin situated on the west. The basin floor subsidence was apparently very slow and quite stable for a long time span. Therefore the peritidal carbonate deposition could compensate the sea-level rise even of long trangression episodes. The role of peritidal complexes increased during high stand when the sedimentation on the Baikit shelf was generally controlled by different-scale mostly low-amplitude fluctuations of the sea level.