North of Siberia: Geology & Petroleum Potential (from Onshore Geology of Siberia to Offshore of Laptev Sea)

Interest in the petroleum potential of the Arctic regions has increased significantly over the past ten years; with the East Siberian sector still representing the most underexplored part of the Arctic. The Laptev Sea shelf lies within this East Siberian sector, but has been comparatively better explored by geophysical methods. The absence of offshore wells has hampered interpretation of existing seismic profiles, with the hypothesised stratigraphy of the Laptev Sea shelf principally derived from onshore analogues. Nonetheless, there are positive indications that the Laptev Sea shelf may have significant hydrocarbon potential. We present here a regional geological study of the northern part of Siberia, including the framing sedimentary basins and fold belts, which represent key areas for predicting the hydrocarbon potential of the Laptev Sea shelf.

A number of sedimentary basins have been superimposed on the northern part of the Siberian Craton- the northern part of the Priverkhoyansk Foreland Basin, Yenisey-Khatanga and Anabar-Lena depressions. These basins were infilled by a thick succession of Late Paleozoic and mainly Mesozoic clastic rocks. Formation and subsidence of the Priverkhoyansk Foreland Basin was closely related to evolution of the Verkhoyansk Foldbelt, whereas the relationship between the other sedimentary basins and neighbouring foldbelts is less clear. Although origin of the Yenisey-Khatanga depression was likely related to Late Paleozoic - Mesozoic rifting, it was subsequently infilled by a thick succession of Cretaceous clastic rocks in a foreland setting to the Taimyr Foldbelt. Consequently the Verkhoyansk and Taimyr foldbelts are believed to extend offshore onto the Laptev Sea shelf and form an acoustic basement, subsequently overprinted by Late Cretaceous-Tertiary rifting.

Interpretation of borehole and outcrop data of Paleozoic and Mesozoic clastic rocks, suggest a wide distribution of fluvial environments and occurrence of wide river systems comparable with the modern Lena river. Huge amounts of clastic material was transported from distant orogenic belts framing the southern, western and probably northern margins of the Siberian Craton, into sedimentary basins located on its eastern and northern margins including the modern Laptev Sea shelf. Fluvial environments were succeeded by relatively Deepwater open-shelf environments accompanied by deposition of organic-rich shales, representing potential hydrocarbon source rocks.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California