The geological evolution of Bjornoya, Arctic Norway; implications for the Barents Shelf

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Authors:Worsley, David; Agdestein, Torleiv; Gjelberg, John G.; Kirkemo, Knut; Mork, Atle; Nilsson, Inger; Olaussen, Snorre; Steel, Ron J.; Stemmerik, Lars
Author Affiliations:Primary:
Norsk Hydro, Oslo, Norway
Other:
Norsk Chevron, Norway
Norsk Hydro Forskningssenter, Norway
Statoil, Norway
SINTEF Petroleum Research, Norway
University of Wyoming, United States
GEUS, Denmark
Volume Title:Norsk Geologisk Tidsskrift
Source:Norsk Geologisk Tidsskrift, 81(3), p.195-234. Publisher: Tapir Academic Press, Oslo, Norway. ISSN: 0029-196X. ISBN: 82-519-1726-3
Publication Date:2001
Note:In English. 98 refs.; illus., incl. sects., strat. cols., 1 table, geol. sketch maps
Summary:The small island of Bjornoya ("Bear Island"), situated in the Barents Sea almost midway between northern Norway and Spitsbergen, displays a Precambrian to Triassic succession in a continuous series of spectacular cliff exposures. These exposures provide a key not only to the evolution of the Stappen High (on which Bjornoya rests) but also to the development of analogous structures along the major lineaments that subsequently contributed to the formation of both the Norwegian-Greenland Sea and the Arctic Ocean. Precambrian to Ordovician dolomites, limestones, quartzites and shales from the basement on which the Upper Palaeozoic succession of Bjornoya was deposited. In latest Devonian and early Carboniferous times the area subsided asymmetrically, probably in response to NE-SW extension; a southwestwards downtilted half-graben developed over the present-day island, with the basinal axis dipping gently NNW. Some 600 m of sandstones, coals and shales are preserved in two upward coarsening sequences. These represent the repeated progradations of sandy fan systems over floodplains with lakes and northward meandering river channels. Mid-Carboniferous (Serpukhovian) uplift was followed by renewed rifting and the same western hinterland again shed debris over its faulted eastern margins. A shift from humid to a semi-arid climate is reflected by the predominantly red colouration of the resultant 200 m thick succession of conglomerates, sandstones and shales, with caliche horizons. Penecontemporaneous regional sea level rise resulted in the gradual replacement of the alluvial floodbasin deposits by shallow marine siliciclastics and carbonates of shoreline, tidal flat and shallow shelf origin. Continued transgression through the Moscovian, perhaps also with decreasing subsidence rates and only intermittent tectonism, is indicated by the gradual change to a marine carbonate-dominated succession, with cherty biomicrites reflecting the establishment of an open carbonate shelf over the entire area. A marked rejuvenation of tectonic activity in the late Moscovian established a different depositional mosaic-faulting affected exposures on the present island along N-S to NE-SW lineaments, with differential subsidence down to the west. This produced erosion of earlier deposits over the eastern part of Bjornoya and deposition of conglomerates, sandstones, shales and dolomites in alluvial gully, coastal and shallow shelf environments to the west. A 200 m thick succession is preserved in western areas and eroded remnants are also preserved as outliers elsewhere on the island. Conglomerate clasts indicate derivation by successive stripping and redeposition of mid-Carboniferous to uppermost Devonian and then basement strata. By the latest Carboniferous the region had again stabilized and platform carbonate deposition resumed, with the development of paleoaplysinid carbonate build-ups. Early Permian flexuring, uplift and peneplanation followed, probably with some transpressive movements. The highly condensed mid to Upper Permian marine succession of mixed siliciclastics and carbonates oversteps all older strata.
Sections:Petrology
Subsections:General
Subjects:Basement; Basins; Carbonate platforms; Carboniferous; Clastic rocks; Climate change; Continental shelf; Correlation; Lithostratigraphy; Mesozoic; Paleoclimatology; Paleozoic; Permian; Red beds; Sea-level changes; Sedimentary rocks; Stratigraphic units; Tectonics; Transgression; Triassic; Arctic Ocean; Barents Sea; Bear Island; Stappen High
Coordinates:N750000 N750000 E0190000 E0190000
Abstract Numbers:02M/3372
Record ID:2004059920
Copyright Information:GeoRef, Copyright 2020 American Geosciences Institute.
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