| Titre | Focused fluid flow and methane venting along the Queen Charlotte fault, offshore Alaska (USA) and British Columbia (Canada) |
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| Auteur | 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  Accès ouvert |
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| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200624 |
| Éditeur | Geological Society of America |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1130/GES02269.1 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Province | Colombie-Britannique |
| Région | Alaska |
| Lat/Long OENS | -139.2500 -128.0000 59.1667 50.5833 |
| Sujets | carbonates; méthane; volcans; Faille de Queen Charlotte ; géochimie; Sciences et technologie |
| Illustrations | cartes de localisation; tableaux; diagrammes; profils de réflexion sismique; représentations graphiques combinées |
| Diffusé | 2020 11 02 |
| Résumé | (disponible en anglais seulement)
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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