A depositional and sequence stratigraphic model for cold-water, spiculitic strata based on the Kapp Starostin Formation (Permian) of Spitsbergen and equivalent deposits from the Barents Sea

Abstract

This article summarizes the lithostratigraphy of two sections through the Kapp Starostin Formation on Spitsbergen having contrasting distal and proximal depositional settings. These outcrop sections are compared with an approximately age-equivalent spiculitic unit penetrated in two exploration wells 800 km to the southeast on the Finnmark Platform. Eight main facies associations comprise these strata, including limestones (matrix-rich, matrix-poor, and mudstone), siliciclastics (shale and sandstone), spiculite (dark/tight and light-colored/porous), and phosphatized surfaces. A sequence stratigraphic model is proposed wherein siliciclastic-limestone intervals represent lowstands of relative sea level, and the spiculites are mainly highstand deposits. Based on this model, seven depositional cycles (sequences) are recognized in the distal, high-accommodation locality on Spitsbergen (Akseloya), four in the proximal locality (Dickson Land), and two on the Finnmark Platform. A speculative model for correlation between these localities is presented, wherein lateral amalgamation of sequences, due to landward pinch-out of some lowstand intervals, results in recognition of fewer sequences in areas of lower accommodation. On both Dickson Land and the Finnmark Platform, an upward change in spiculite lithology from dark/tight to light/porous is shown, and Dickson Land also shows an upward change in siliciclastic lithology from shale to glauconitic sandstone. These changes record a long-term shoaling trend approaching the Permian-Triassic boundary. This model provides a basis for interpreting the basin-scale (Begin page 2062) distribution of lithofacies and predicting the occurrence of porous zones representing potential hydrocarbon reservoirs.