| Title | Focused fluid flow and methane venting along the Queen Charlotte fault, offshore Alaska (USA) and British Columbia (Canada) |
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| Author | Prouty, N G; Brothers, D S; Kluesner, J W; Barrie, J V ; Andrews, B D; Lauer, R M; Greene, H G; Conrad, J E; Lorenson, T D; Law, M D; Sahy, D; Conway, K; McGann, M L; Dartnell, P |
| Source | Geosphere vol. 16, issue 6, 2020 p. 1336-1357, https://doi.org/10.1130/GES02269.1  Open Access |
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| Year | 2020 |
| Alt Series | Natural Resources Canada, Contribution Series 20200624 |
| Publisher | Geological Society of America |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | British Columbia |
| Area | Alaska; United States of America; Canada |
| Lat/Long WENS | -139.2500 -128.0000 59.1667 50.5833 |
| Subjects | geochemistry; Science and Technology; carbonates; methane; volcanoes; Queen Charlotte fault |
| Illustrations | location maps; tables; diagrams; seismic reflection profiles; cross-plots |
| Released | 2020 11 02 |
| 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. |
| GEOSCAN ID | 327892 |
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