Subsea ice-bearing permafrost on the U.S. Beaufort Margin : 1. Minimum seaward extent defined from multichannel seismic reflection data

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Brothers, Laura L., Herman, Bruce M., Hart, Patrick E., Ruppel, Carolyn D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley & Sons 2016
• Subjects: Subsea permafrost; Gas hydrates; Multichannel seismic data; Arctic Ocean; Arctic; Beaufort Shelf; Ice; Methane hydrate; permafrost
• Online Access: https://hdl.handle.net/1912/8744

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): 4354–4365, doi:10.1002/2016GC006584. Subsea ice-bearing permafrost (IBPF) and associated gas hydrate in the Arctic have been subject to a warming climate and saline intrusion since the last transgression at the end of the Pleistocene. The consequent degradation of IBPF is potentially associated with significant degassing of dissociating gas hydrate deposits. Previous studies interpreted the distribution of subsea permafrost on the U.S. Beaufort continental shelf based on geographically sparse data sets and modeling of expected thermal history. The most cited work projects subsea permafrost to the shelf edge (∼100 m isobath). This study uses a compilation of stacking velocity analyses from ∼100,000 line-km of industry-collected multichannel seismic reflection data acquired over 57,000 km2 of the U.S. Beaufort shelf to delineate continuous subsea IBPF. Gridded average velocities of the uppermost 750 ms two-way travel time range from 1475 to 3110 m s−1. The monotonic, cross-shore pattern in velocity distribution suggests that the seaward extent of continuous IBPF is within 37 km of the modern shoreline at water depths < 25 m. These interpretations corroborate recent Beaufort seismic refraction studies and provide the best, margin-scale evidence that continuous subsea IBPF does not currently extend to the northern limits of the continental shelf. DOE NETL/NRC Methane Hydrate Fellowship Grant Number: DE-FC26-05NT42248; USGS–DOE Interagency Agreements Grant Number: DE-FE000291 and 0023495 2017-05-04