Subsea ice-bearing permafrost on the U.S. Beaufort Margin : 2. Borehole constraints
Ruppel, Carolyn D.
Herman, Bruce M.
Brothers, Laura L.
Hart, Patrick E.
MetadataShow full item record
Borehole logging data from legacy wells directly constrain the contemporary distribution of subsea permafrost in the sedimentary section at discrete locations on the U.S. Beaufort Margin and complement recent regional analyses of exploration seismic data to delineate the permafrost's offshore extent. Most usable borehole data were acquired on a ∼500 km stretch of the margin and within 30 km of the contemporary coastline from north of Lake Teshekpuk to nearly the U.S.-Canada border. Relying primarily on deep resistivity logs that should be largely unaffected by drilling fluids and hole conditions, the analysis reveals the persistence of several hundred vertical meters of ice-bonded permafrost in nearshore wells near Prudhoe Bay and Foggy Island Bay, with less permafrost detected to the east and west. Permafrost is inferred beneath many barrier islands and in some nearshore and lagoonal (back-barrier) wells. The analysis of borehole logs confirms the offshore pattern of ice-bearing subsea permafrost distribution determined based on regional seismic analyses and reveals that ice content generally diminishes with distance from the coastline. Lacking better well distribution, it is not possible to determine the absolute seaward extent of ice-bearing permafrost, nor the distribution of permafrost beneath the present-day continental shelf at the end of the Pleistocene. However, the recovery of gas hydrate from an outer shelf well (Belcher) and previous delineation of a log signature possibly indicating gas hydrate in an inner shelf well (Hammerhead 2) imply that permafrost may once have extended across much of the shelf offshore Camden Bay.
Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 17 (2016): 4333–4353, doi:10.1002/2016GC006582.
Showing items related by title, author, creator and subject.
Progress report on the development of the seafloor borehole array seismic system (phase II) : July 14, 1992 to January 31, 1996 Stephen, Ralph A.; Peal, Kenneth R.; Bolmer, S. Thompson; Gould, Matthew R.; Koelsch, Donald E.; Orcutt, John A.; Vernon, Frank L.; Offield, G.; Willoughby, David F.; Hollinshead, C. B.; Spiess, Fred N.; Hildebrand, John; Zimmerman, R.; Austin, G. (Woods Hole Oceanographic Institution, 1996-06)The Seafloor Borehole Array Seismic System (SEABASS) was originally developed to record autonomously on the seafloor the signals received on a four-sonde three-component borehole geophone array in the VLF band (2-50Hz)(Stephen ...
An effective medium inversion algorithm for gas hydrate quantification and its application to laboratory and borehole measurements of gas hydrate-bearing sediments Chand, Shyam; Minshull, Tim A.; Priest, Jeff A.; Best, Angus I.; Clayton, Christopher R. I.; Waite, William F. (Blackwell Publishing, 2006-07-04)The presence of gas hydrate in marine sediments alters their physical properties. In some circumstances, gas hydrate may cement sediment grains together and dramatically increase the seismic P- and S-wave velocities of the ...
Stephen, Ralph A.; Swift, Stephen A.; Bolmer, S. Thompson (Woods Hole Oceanographic Institution, 1987-03)This report describes a preliminary analysis of borehole seismic data to determine VLF/Sub-bottom Seismic Noise in the Atlantic and the preliminary results of finite difference modelling for a Cape Fear environment. Noise ...