Print this pageS. N. Ehrenberg1, N. A. H. Pickard2, L. B. Henriksen3, T. A. Svånå3, P. Gutteridge4, D.I.M. Macdonald5
(1) Statoil, N-4035 Stavanger, Norway
(2) Cambridge Carbonates, Ltd. and Department of Earth Sciences, University of Wales, Cardiff, United Kingdom
(3) Statoil, Harstad, Norway
(4) Cambridge Carbonates, Ltd, Nottingham, United Kingdom
(5) Department of Geology & Petroleum Geology, University of Aberdeen, United Kingdom
ABSTRACT: 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
This study 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 exploration wells 800 km to the southeast, on the Finnmark Platform.
Eight facies associations comprise these strata, including limestones (transgressive shoreline brachiopod rudstones; offshore bryozoan wacke-packstone banks; and basinal silty argillaceous mudstone), siliciclastics (siliceous shale and glauconitic sandstone), spiculite (dark-colored/tight and light-colored/porous), and phosphatized surfaces. The bryozoan limestone banks can be seen exposed in cross-section on Spitsbergen and in plan-view as seismic-amplitude anomalies on the Finnmark Platform.
A sequence stratigraphic model is proposed wherein siliciclastic-limestone intervals represent lowstands and the spiculites are highstand deposits. Based on this model, 7 depositional sequences are recognized in the distal, high-accommodation locality on Spitsbergen (Akseløya), 4 in the proximal locality (Dickson Land), and 2 on the Finnmark Platform. Lateral amalgamation of sequences, due to landward pinchout of some lowstand intervals, results in recognition of fewer sequences in areas of lower accommodation.
On both Dickson Land and the Finnmark Platform, there is an upward change in spiculite lithology from dark/tight to light/porous, 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 distribution of lithofacies and predicting the occurrence of porous spiculite zones representing potential hydrocarbon reservoirs.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado