Deep electrical structure of the northern Cascadia (British Columbia, Canada) subduction zone: Implications for the distribution of fluids

Abstract

Research Article| January 01, 2006 Deep electrical structure of the northern Cascadia (British Columbia, Canada) subduction zone: Implications for the distribution of fluids Wolfgang Soyer; Wolfgang Soyer 1 Institute of Geophysical Research, University of Alberta, Edmonton, Alberta T6G 2J1, Canada Search for other works by this author on: GSW Google Scholar Martyn Unsworth Martyn Unsworth 1 Institute of Geophysical Research, University of Alberta, Edmonton, Alberta T6G 2J1, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Wolfgang Soyer 1 Institute of Geophysical Research, University of Alberta, Edmonton, Alberta T6G 2J1, Canada Martyn Unsworth 1 Institute of Geophysical Research, University of Alberta, Edmonton, Alberta T6G 2J1, Canada Publisher: Geological Society of America Received: 11 Jun 2005 Revision Received: 04 Sep 2005 Accepted: 18 Sep 2005 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2006) 34 (1): 53–56. https://doi.org/10.1130/G21951.1 Article history Received: 11 Jun 2005 Revision Received: 04 Sep 2005 Accepted: 18 Sep 2005 First Online: 09 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 Wolfgang Soyer, Martyn Unsworth; Deep electrical structure of the northern Cascadia (British Columbia, Canada) subduction zone: Implications for the distribution of fluids. Geology 2006;; 34 (1): 53–56. doi: https://doi.org/10.1130/G21951.1 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 SocietyGeology Search Advanced Search Abstract Long-period magnetotelluric data have been used to image the deep electrical structure of the Cascadia subduction zone in British Columbia, Canada. Zones of elevated electrical conductivity were found in both the forearc and backarc regions and are interpreted as a consequence of the fluid release from subducting slab. A shallow zone of high conductivity beneath Vancouver Island is likely due to fluids that are trapped above the subducting plate. East of this structure is a conductive (∼0.03 S/m) forearc mantle wedge that also exhibits low seismic velocities and may be serpentinized. A free fluid phase is required to account for this enhanced conductivity. Elevated conductivities are observed in the upper mantle throughout the backarc (∼0.01 S/m) and strongly support the hypothesis of a shallow, convecting asthenosphere. This enhanced upper mantle conductivity can be explained by either hydrogen ion diffusion in olivine minerals, or by a few percent partial melting (<4%). You do not have access to this content, please speak to your institutional administrator if you feel you should have access.