Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Ehrenberg, S. N. Articles by Svånå, T. A. Search for Related Content GeoRef GeoRef Citation

Use of Spectral Gamma-Ray Signature to Interpret Stratigraphic Surfaces in Carbonate Strata: An Example from the Finnmark Carbonate Platform (Carboniferous-Permian), Barents Sea

¹ Statoil, N-4035 Stavanger, Norway; sne{at}statoil.com
² Statoil, Postboks 40, N-9401 Harstad, Norway; tasv{at}statoil.com

Steve Ehrenberg has a Ph.D. from University of California-Los Angeles. He joined Statoil in 1985, where he does technical service projects in clastic and carbonate petrology. In between there is time for the occasional scientific article.Tore Svana received his Candidatus Scientiarium degree in geology (sedimentology) at the University of Oslo in 1984. He began his professional career as well site/operations geologist, first at Norsk Hydro and thereafter at Statoil. He has worked mainly on Barents Sea exploration, with particular emphasis on Upper Paleozoic carbonates. He has also been involved in the evaluation of Mideast opportunities, was the leader for Statoil's former carbonate research program, and has co-authored several publications.

Spectral gamma-ray (GR) profiles were examined in well 7128/6-1, the stratigraphic reference section of the entirely subsurface Finnmark carbonate platform. Detailed bulk-chemical profiling of selected GR peaks shows that potassium (K) and thorium (Th) are mutually correlated and are a direct index of siliciclastic (aluminosilicate) content, whereas uranium (U) is uncorrelated with K, Th, and all other chemical components measured. Uranium tends to be enriched in thin shale and argillaceous carbonate layers within otherwise carbonate-dominated intervals. Uranium is thus associated with aluminosilicate minerals and is not particularly concentrated in dolomite. Two types of GR peaks are observed. Potassium-thorium-dominated peaks are suggested to indicate relatively major transgressions during which aluminosilicate detritus was derived from sources interior to the Fennoscandian shield. Uranium-dominated peaks correspond with relatively minor transgressions within intervals of cyclic shallow-water carbonate deposits. Uranium-enriched aluminosilicate detritus is suggested to be the product of extended subaerial exposure of the platform, during which U was concentrated by groundwater movement. These results can be useful as a basis for applying spectral GR signature as a tool for stratigraphic interpretation in uncored or incipiently understood carbonate sections.

This article has been cited by other articles:

				S. N. Ehrenberg, T. A. Svana, and P. K. Swart Uranium depletion across the Permian-Triassic boundary in Middle East carbonates: Signature of oceanic anoxia AAPG Bulletin, June 1, 2008; 92(6): 691 - 707. [Abstract] [Full Text] [PDF]

				Factors controlling porosity in Upper Carboniferous-Lower Permian carbonate strata of the Barents Sea AAPG Bulletin, December 1, 2004; 88(12): 1653 - 1676.

				Cement Geochemistry of Photozoan Carbonate Strata (Upper Carboniferous-Lower Permian), Finnmark Carbonate Platform, Barents Sea Journal of Sedimentary Research, January 1, 2002; 72(1): 95 - 115.