Publication Date
12-1-2020
Document Type
Article
Publication Title
Geosphere
Volume
16
Issue
6
DOI
10.1130/GES02269.1
First Page
1336
Last Page
1357
Abstract
Fluid seepage along obliquely deforming plate boundaries can be an important indicator of crustal permeability and influence on fault-zone mechanics and hydrocarbon migration. The ~850-km-long Queen Charlotte fault (QCF) is the dominant structure along the right-lateral transform boundary that separates the Pacific and North American tectonic plates offshore southeastern Alaska (USA) and western British Columbia (Canada). Indications for fluid seepage along the QCF margin include gas bubbles originating from the seafloor and imaged in the water column, chemosynthetic communities, precipitates of authigenic carbonates, mud volcanoes, and changes in the acoustic character of seismic reflection data. Cold seeps sampled in this study preferentially occur along the crests of ridgelines associated with uplift and folding and between submarine canyons that incise the continental slope strata. With carbonate stable carbon isotope (8”C) values ranging from -46%o to -3%, there is evidence of both microbial and thermal degradation of organic matter of continental-margin sediments along the QCF. Both active and dormant venting on ridge crests indicate that the development of anticlines is a key feature along the QCF that facilitates both trapping and focused fluid flow. Geochemical analyses of methane-derived authigenic carbonates are evidence of fluid seepage along the QCF since the Last Glacial Maximum. These cold seeps sustain vibrant chemosynthetic communities such as clams and bacterial mats, providing further evidence of venting of reduced chemical fluids such as methane and sulfide along the QCF.
Funding Sponsor
U.S. Geological Survey
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Department
Moss Landing Marine Laboratories
Recommended Citation
Nancy G. Prouty, Daniel S. Brothers, Jared W. Kluesner, J. Vaughn Barrie, Brian D. Andrews, Rachel M. Lauer, H. Gary Greene, James E. Conrad, Thomas D. Lorenson, Michael D. Law, Diana Sahy, Kim Conway, Mary L. McGann, and Peter Dartnell. "Focused fluid flow and methane venting along the Queen Charlotte fault, offshore Alaska (USA) and British Columbia (Canada)" Geosphere (2020): 1336-1357. https://doi.org/10.1130/GES02269.1
Comments
This is the Version of Record and can also be read online here.