About This Item
- Full TextFull Text(subscription required)
- Pay-Per-View PurchasePay-Per-View
Purchase Options Explain
Share This Item
The AAPG/Datapages Combined Publications Database
AAPG Bulletin
Abstract
(Begin page 295)
AAPG Bulletin, V.
Use of spectral gamma-ray signature to interpret stratigraphic surfaces in
carbonate strata: An example from the Finnmark carbonate platform (Carboniferous-Permian),
Barents Sea
S. N. Ehrenberg,1 T. A.
Svånå2
1Statoil, N-4035 Stavanger, Norway; email: [email protected]
2Statoil, Postboks 40, N-9401 Harstad, Norway; email: [email protected]
AUTHORS
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 Svånå 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.
ACKNOWLEDGMENTS
Helpful suggestions on the manuscript were contributed by L. Stemmerik, E. G. Purdy, and AAPG referees J. H. Doveton, S. C. Ruppel, and T. Elliott.
ABSTRACT
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.
(Begin page 296)
Pay-Per-View Purchase Options
The article is available through a document delivery service. Explain these Purchase Options.
Watermarked PDF Document: $14 | |
Open PDF Document: $24 |
AAPG Member?
Please login with your Member username and password.
Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].