Hemipelagic deposition of the Silurian Kepingtage formation in Tarim basin and its sedimentologic significance

Abstract

Hemipelagic contourites were interpreted in the Silurian Kepingtage (柯坪塔格) Formation in the Tarim basin, Northwest China, through studies of outcrop, core, well-log, and seismic data. They are characterized by thin to thick bedded mudstone, with contour current irregularly thin bedded-lentiform siltstone and sandstone. Chitin stone, graptolite, thin-shelled bivalve, dissoconch, and acritatch fossils are present in dark-colored mudstones. A Helminthopsis-Scolicia trace fossil assemblage was observed in the outcrop and drilling core. Sandstones are mainly well-sorted and subangular-subrounded sublitharenite. Sedimentary structures include oriented current structure, erosional surface, and small-scale cross stratifications. The potential of contourites as hydrocarbon source and reservoir rocks was evaluated on the basis of previous interpretations of paleoclimate and paleosalinity.

Keywords

Tarim basin / Silurian / hemipelagic deposit / contourite

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