Print this pageInsights into the Formation and Sedimentary Fill of the West Siberian Basin: Structural, Sedimentological and Provenance Analysis
Clare Davies1, Mark Allen2, Mikhail
Buslov3, Inna Safonova3, and Elena Soloboeva3
1 Cambridge University, Cambridge, United Kingdom
2 Durham University, Durham, United Kingdom
3 Russian Academy of Sciences, Novosibirsk, Russia
The West Siberian Basin is one of the largest hydrocarbon basins in the world, covering an area of ~3,000,000 km2 , and lies between the East European and Siberian cratons. Wells have shown the basement to be of buried arcs, accretion complexes and microcontinents, similar to the geology of the Urals and Altaid mountains surrounding the basin, rather than Precambrian shield geology of the neighbouring cratons. Extension of the basin occurred close to the Permian-Triassic boundary, with rift geometries in the northeast of the basin defining a triple junction believed to be associated with impact from the Siberian plume. Flood basalt emplacement is found within the rifted basement grabens.
Post-rift subsidence of the basin resulted in deposition of a thick Mesozoic section, containing key source and reservoir intervals. During the same period punctuated deformation and uplift occurred at the basin margins, considered to result from orogenies along the southern margin of Eurasia. Late Cenozoic folding in the basin is a key factor for creating successful traps and again is considered to be caused by the India-Eurasia continent collision to the south.
Exposures of late Paleozoic – Mesozoic strata in the southeastern part of the basin (Kuzbass region) were examined during 2004 fieldwork and contain punctuated intervals of fluvial conglomerates and subtle angular unconformities. These conglomerates are interpreted to represent increased sediment supply into the West Siberian Basin, independent of eustasy, and instead are related to episodes of compressional deformation at the southern margin of Eurasia. The most striking of these unconformities took place at the Triassic-Jurassic boundary. The sediment source area, defined from clast composition, appears to be the Altaid mountains to the south; this is a lithic rich source area which may have provided poor-quality reservoir sediments.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005