LITHOPALEOGRAPHIC RECONSTRUCTIONS OF THE MIDDLE JURASIC EPOCH IN THE NORTH OF WEST SIBERIA AND THE KARA SEA AREA

G. G. Shemin, L. G. Vakulenko, V. I. Moskvin, V. V. Sapyanik

The Jurassic period is an important stage of sedimentary cover formation in the north of West Siberia and the Kara Sea area. Many regional reservoirs and pay horizons with numerous discovered oil and gas pools, which are targets of further petroleum exploration, were formed during the period. Then, depositional environment within the region under study changed consistently and regularly. There was a regular repeated alternation of marine transgression with extending outlines and deepening sea basin and regression accompanied by its shallowing and some decrease in sedimentation area. Detailed correlation of Jurassic deposits and their geological, lithofacies, geochemical, and paleontological analysis enabled the construction of 13 lithopaleogeographic maps of the Jurassic period of the northern West Siberia and the Kara Sea area. The maps show erosion areas and the areas of continental (alluvial plains), transitional (coastal plains sometimes submerged under the sea), and marine (shallow water, shallow shelf, deep shelf) sedimentation. The paper provides the research data only on the Middle Jurassic epoch (excluding the Callovian age): the Layda, Vymskoye, Leontyevskoye, and Malyshevka time, as the Early and Late Jurassic epochs and the Callovian age have been discussed by the authors in their previous works.

Key words: lithopaleogeographic reconstructions, paleogeographic region, lithological region, thickness, land, shallow water, shallow shelf, deep shelf, material composition, geochemical parameters, macrofauna.

DOI 10.20403/2078-0575-2016-2-65-77

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