--> ABSTRACT: Depositional Evolution of the Finnmark Carbonate Platform, Barents Sea, by S. N. Ehrenberg, E. B. Nielsen, T. A. Svana, and L. Stemmerik; #91019 (1996)

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Depositional Evolution of the Finnmark Carbonate Platform, Barents Sea

S. N. Ehrenberg, E. B. Nielsen, T. A. Svana, and L. Stemmerik

Due to its extensive core coverage (444 m of the 530 m thick succession) well 7128/6-1 provides a unique opportunity for detailed sedimentologic study of this entirely sub-surface Carboniferous/Permian carbonate platform. This "reference section" is augmented by 51 m of core in well 7128/4-1, 25 km to the west. Trends in microfacies, inferred water depth, cycle thickness, and gamma ray profile are used to differentiate a hierarchy of stratigraphic sequences, reflecting probable 5th through 2nd order fluctuations in relative sealevel. Wide variations in the nature of the sequences, sequence boundaries, and component cycles record the changing interplay of eustacy, tectonics, siliciclastic influx, and climate during the 50-60 m.y. history of platform evolution. We recognize 8 third-order sequences: Sequence 1 (?Moskovian) consists of limestone/sandstone cycles. Sequence 2 (Kasimovian-Asselian) evolves from thick shale/silt/wackestone cycles to thin dolomitic (sabkha/lagoon) mudstone cycles. Sequence 3 (Asselian) consists of thick fusulinid-wackestone/Palaeoaplysina-buildup cycles overlain by thin dolomitic mudstone cycles. The 2/3 and 3/4 boundaries are gradational zones of minimal cycle thickness, while other sequence boundaries are sharply defined. Sequence 4 (Asselian) is a series of thin shallow-shelf cycles. Sequence 5 (Sakmarian) begins with transgressive shale to shallow-shelf cycles progressing to uniformly shallow-shelf deposition. Sequences 6 to 8 (Artinskian-Late Permian) lack high-frequency cycles, reflecting the 2nd order trend of progressively higher relative sealevel from Asselian time onward.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California