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Composition and Sedimentation Pecularities of the Upper Jurassic-Lower Cretaceous Black Shale Bazhenov Formation in the Central Part of West Siberia
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 6th EAGE Saint Petersburg International Conference and Exhibition, Apr 2014, Volume 2014, p.1 - 5
Abstract
A detailed study of the lithological sections of the Upper Jurassic-Lower Cretaceous black shale Bazhenov Formation was made in the central part of the West Siberian geosyneclise (Salymskiy and surrounding regions). It is observed the following upward sequence of rocks in most of the studied sections: siliceousclayey rocks – radiolarian cherts - microcrystalline cherts – mixtites (calcite, quartz, clay, organic matter about 15–20 % each). Gradual increase of clastic material in the rocks is fixed, and different stages (from early to late) of sea level high stand are established. The most favorable period for the accumulation of organic matter (OM) was the late stage of high sea level stand (LHST1). In the present study, in Western Siberia on the border of the Jurassic and Cretaceous stages it is observed: a. abnormally high (the maximum for the section of Formation) uranium content; b. change of biogenic siliceous sedimentation to the siliceous-carbonate one. This change in sedimentation during this period also was recorded in the Tethyan belt, and is associated with the global restructuring of the geochemical conditions in the oceanic waters of the northern hemisphere in the J/K boundary.