The Queen Charlotte-Fairweather Fault Zone - The Knife-Edged Pacific-North American Plate Boundary
Abstract
Recent investigations of the Queen Charlotte-Fairweather (QC-FW) Fault zone using multibeam echosounder bathymetric and 3.5-kHz sub-bottom profile data show that the fault zone is primarily represented by a single linear structure with small, localized pull-apart basins suggestive of transtension. Water column acoustical data imaged gas plumes concentrated along the fault zone with plume columns extending as much as 700 m above the crest of mud volcanoes. Piston cores indicate that the fault zone cuts hard-packed dense sands that have been dated as Pleistocene in age. The newly discovered fluids associated with the southern half of the fault zone and volcanic edifices with oceanic and continental plate petrologic affinities suggest that the QC-FW is a leaky transform system. Two independent investigations, one in the north part and one in the central part of the fault zone, using two different types of piercing points, found that the slip rate along at least a 200 km length was consistent at between 40-55 mm/yr. since about 14 ka, equivalent to the relative plate motion between the Pacific and North American plates in the NE Pacific region. We surmise that the QC-FW is accommodating most, if not all, of relative motion along a single primary strand without any detectable partitioning of motion onto other faults. This right-lateral strike-slip fault zone is expressed on the seafloor as a very straight feature that probably represents nearly pure strike-slip motion.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMOS12B..08G
- Keywords:
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- 4306 Multihazards;
- NATURAL HAZARDSDE: 4313 Extreme events;
- NATURAL HAZARDSDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8110 Continental tectonics: general;
- TECTONOPHYSICS