High-resolution seismic and resistivity profiling of a buried Quaternary subglacial valley: Northern Alberta, Canada

Research Article| November 01, 2009 High-resolution seismic and resistivity profiling of a buried Quaternary subglacial valley: Northern Alberta, Canada Jawwad Ahmad; Jawwad Ahmad 1Institute for Geophysical Research, Department of Physics, Mailstop #615, University of Alberta, Edmonton, Alberta T6G 2G7, Canada Search for other works by this author on: GSW Google Scholar Douglas R. Schmitt; Douglas R. Schmitt † 1Institute for Geophysical Research, Department of Physics, Mailstop #615, University of Alberta, Edmonton, Alberta T6G 2G7, Canada †E-mail: doug@phys.ualberta.ca or doug.schmitt@gmail.com Search for other works by this author on: GSW Google Scholar C. Dean Rokosh; C. Dean Rokosh 1Institute for Geophysical Research, Department of Physics, Mailstop #615, University of Alberta, Edmonton, Alberta T6G 2G7, Canada 2Alberta Geological Survey, 4th Floor, Twin Atria Building, 4999-98 Ave. NW, Edmonton, Alberta T6B 2X3, Canada Search for other works by this author on: GSW Google Scholar John G. Pawlowicz John G. Pawlowicz 2Alberta Geological Survey, 4th Floor, Twin Atria Building, 4999-98 Ave. NW, Edmonton, Alberta T6B 2X3, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Jawwad Ahmad 1Institute for Geophysical Research, Department of Physics, Mailstop #615, University of Alberta, Edmonton, Alberta T6G 2G7, Canada Douglas R. Schmitt † 1Institute for Geophysical Research, Department of Physics, Mailstop #615, University of Alberta, Edmonton, Alberta T6G 2G7, Canada C. Dean Rokosh 1Institute for Geophysical Research, Department of Physics, Mailstop #615, University of Alberta, Edmonton, Alberta T6G 2G7, Canada 2Alberta Geological Survey, 4th Floor, Twin Atria Building, 4999-98 Ave. NW, Edmonton, Alberta T6B 2X3, Canada John G. Pawlowicz 2Alberta Geological Survey, 4th Floor, Twin Atria Building, 4999-98 Ave. NW, Edmonton, Alberta T6B 2X3, Canada †E-mail: doug@phys.ualberta.ca or doug.schmitt@gmail.com Publisher: Geological Society of America Received: 05 Aug 2007 Revision Received: 22 Jan 2009 Accepted: 24 Feb 2009 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2009 Geological Society of America GSA Bulletin (2009) 121 (11-12): 1570–1583. https://doi.org/10.1130/B26305.1 Article history Received: 05 Aug 2007 Revision Received: 22 Jan 2009 Accepted: 24 Feb 2009 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jawwad Ahmad, Douglas R. Schmitt, C. Dean Rokosh, John G. Pawlowicz; High-resolution seismic and resistivity profiling of a buried Quaternary subglacial valley: Northern Alberta, Canada. GSA Bulletin 2009;; 121 (11-12): 1570–1583. doi: https://doi.org/10.1130/B26305.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract High-resolution seismic and resistivity profiles were acquired to assist in the delineation of a buried Quaternary subglacial valley, the existence of which was first discovered by drilling. One aspect of this valley is the glacial sediments that host substantial methane at shallow depths (~50 m or less). Geophysical well logs indicate that the glacial sediments in this area generally have lower compressional wave speeds VP <1800 m/s and greater electrical resistivity r >10 Ω·m than adjacent undisturbed Cretaceous-age rocks, which have VP >2200 m/s and r <10 Ω·m, respectively. Seismic-refraction velocities, seismic-reflection architecture, and electrical resistivity tomography images all indicate a deep (>300 m) valley. The reflection profile reveals a complex series of events consistent with heterogeneous deposition. One major reflection dips eastward across the valley. The reflection character changes abruptly on either side of this event, with dipping clinoform reflections beneath and nearly horizontal reflections above. These may be related to changes in deposition processes beneath a retreating ice sheet, as has been suggested by earlier workers. The buried valley's basal reflections are complex and possibly reflect glaciotectonic deformation or block plucking. The near-surface methane gas is within, but at the edge of, the valley. The methane gas–saturated zone displays anomalously high resistivities both in the well logs and in resistivity tomography. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.