Anoxic sedimentogenesis of ediacaran and silurian strata of south-western slope of the East-European platform
Journal Title: Геодинаміка - Year 2017, Vol 22, Issue 1
Abstract
Purpose. The objective of this study was to investigate the depositional environments of organic-rich Ediacaran and Silurian strata on the south-western slope of the East-European platform. In particular, the factors facilitating the efficient fossilization of organic matter in marine sediments and which play the key role in black shales formation, are the basic elements of petroleum systems being considered. Methodology. Methodology is based on lithological investigations, which allowed establishing the material composition of rocks, the spatial extent of the successions under study and their thicknesses, and the range of occurrence in the sequence and reconstruction of palaeoenvironment in the studied age intervals. Results. Investigations of the organic-rich platform deposits of Ediacaran (Kalus beds) and Silurian have been performed. It was established that Kalus beds occur as a continuous band along the south-western slope of the East-European platform reaching the Ukrainian Shield. Their thickness is 90 meters and more within the Volyno-Podillya plate and Moldova plate, while in Dobrogea Foredeep it is 150 meters and more. For Silurian strata it was established that organic-rich deposits (argillites, marls) occur within the most subsided part of the platform, where the thicknesses of Silurian reach 700m and more. On the basis of lithological investigations the reconstruction of the paleo-environments in Ediacaran and Silurian, which caused the anoxic sedimentogenesis within these ranges of the geological history. It was established that the marine basin in Kalus times that covered the large territory of the craton Baltica, where the oxygen-minimum zone in the water column started at depths of maximum 100 meters. The reconstruction of the paleo-environment in Silurian shows that the basin had paleo-bathymetric zoning. Till depth was about 100m of deposited sulfate, clay-carbonate, and carbonate (reef) sediments, while the organic-rich ones were deposited at depths of over 100m within the oxygen-minimum zone. Originality. For Ediacaran deposits their occurrence, thicknesses, and petroleum-generating potential have been established. For Silurian the areas of the most prospective rocks’ occurrence have been elucidated. It was established that deposition of the organic-rich rocks has been controlled by the oxygen-minimum zone. Practical significance. Results of investigations allowed establishing the petroleum-generating potential for Ediacaran deposits and distinguishing the areas of occurrence of the most prospective organic-rich Silurian rocks (mudstones, marls), which represent a potential resource for shale gas exploration and production.
Authors and Affiliations
N. Radkovets
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Anoxic sedimentogenesis of ediacaran and silurian strata of south-western slope of the East-European platform
Purpose. The objective of this study was to investigate the depositional environments of organic-rich Ediacaran and Silurian strata on the south-western slope of the East-European platform. In particular, the factors fac...