Carboniferous History of North-Eastern Part of Siberian Craton: from Rift to Passive Margin

Victoria Ershova¹, Andrei Khudoley¹, and Andrei Prokopiev^2
1Saint Petersburg State University, Saint Petersburg, Russian Federation.
²Diamond and Precious Metal Geology Institute Siberian Branch Russian Academy of Sciences, Yakutsk, Russian Federation.

Study area is located on the northeast margin of the Siberian Craton. The lowermost Carboniferous strata are represented by thick succession (up to 250 m) of limestone with admixture of clastic material. These deposits were formed in wide epeiric sea in relatively shallow-water environment. Lower Visean deposits overlie Tournaisian limestones with stratigraphic gap at the base. The Lower Visean deposits sporadically distributed within study area are mainly represented by chert beds up to 50 m thick. Only in several localities sandy and conglomeratic turbidite successions up to 250 m thick were observed. Deposition of the Lower Visean sandy turbidities corresponded to the latest stage of the Middle Paleozoic rifting of the Siberian Craton. The rift-dominated phase resulted in uplifted shoulders, steep topography and intense sediment input. The northern part of Siberian shelf was incised by several submarine valleys during the Early Visean. In the latest Early Visean significant changes in depositional environment occurred. During this period predominantly siltstones with interlayers of sandstones were deposited (thickness is up to 150 m) primarily in prodelta environment. They conformably overlie different types of the Lower Visean deposits showing disappearance of local uplifts and depressions. This shift in sedimentary environments corresponds to rift-drift transition and marks the initial phase of passive margin evolution.

Serpukhovian- Late Carboniferous is characterized by formation of up to 1 km thick succession mainly composed of shale and siltstones with rare thin interlayers of sandstone. The most probable depositional environment of these strata is a mud-rich submarine fan, typical for mature passive margins.

The uppermost Carboniferous deposits (up to 300 m) predominantly consist of siltstones and sandstones deposited in deltaic environment showing gradual filling in of the sedimentary basin. Passive margin sedimentation continued up to Late Jurassic.

Acknowledgments.
The study was supported by TGS-NOPEC Geophysical Company, foundation of President of Russia for Young Scientist grant N MK-2044.2010.5, foundation of Saint-Petersburg State University and Ministry of Science and Education of Russian government grant N 14.740.11.0187.

AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.