气候变化领域集成服务门户(CCPortal): The Northern Terminus of Cascadia Subduction

CCPortal

DOI	10.1029/2019JB018453
	The Northern Terminus of Cascadia Subduction
	Savard G.; Bostock M.G.; Hutchinson J.; Kao H.; Christensen N.I.; Peacock S.M.
发表日期	2020
ISSN	21699313
卷号	125 期号:6
英文摘要	The Juan de Fuca (JDF) plate system is pivoting and breaking apart as a result of resistance to subduction. At the northern end, the Explorer (EXP) plate moves independently of the JDF plate along the Nootka Fault Zone (NFZ), which forms an unstable triple junction with the JDF ridge and the Sovanco Fracture Zone. We trace the subsurface extension of the NFZ using tomography by combining results from a new nearshore study with a previous ocean-bottom study and other geophysical constraints. Cross sections from the offshore NFZ through central Vancouver Island suggest a strong fold in the subducting lithosphere (∼40°). Near the deformation front, the NFZ is defined by microseismicity that extends into oceanic mantle with low VP/VS (<1.7) values. This anomaly extends to the NE below the continental shelf with a more northerly trajectory than common NFZ depictions through the seismicity concentration off Nootka Island. Tremor locations and receiver functions indicate that this more northerly trajectory persists across Vancouver Island. We propose a revised tectonic evolution for the NFZ that leads to (i) an EXP microplate confined to shallow depths below the convergent margin and which underthrusts North America no farther landward than Brooks Peninsula and (ii) a northern edge of Cascadia subduction that cuts between Brooks Peninsula and Nootka Island. The plate fold offshore Nootka Island and abundant seismicity there and at Brooks Peninsula are ascribed to stress concentrations on either side of the NFZ associated with deformation at the edges of more competent JDF, EXP, and North American plates. ©2020. American Geophysical Union and Her Majesty the Queen in Right of Canada. Reproduced with the permission of Natural Resources Canada.
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187823
作者单位	Department of Earth, Ocean & Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada; Now at Department of Geoscience, University of Calgary, Calgary, Canada; School of Earth & Ocean Sciences, University of Victoria, Victoria, BC, Canada; Pacific Geoscience Center, Geological Survey of Canada, Ottawa, ON, Canada
推荐引用方式 GB/T 7714	Savard G.,Bostock M.G.,Hutchinson J.,et al. The Northern Terminus of Cascadia Subduction[J],2020,125(6).
APA	Savard G.,Bostock M.G.,Hutchinson J.,Kao H.,Christensen N.I.,&Peacock S.M..(2020).The Northern Terminus of Cascadia Subduction.Journal of Geophysical Research: Solid Earth,125(6).
MLA	Savard G.,et al."The Northern Terminus of Cascadia Subduction".Journal of Geophysical Research: Solid Earth 125.6(2020).