气候变化领域集成服务门户(CCPortal): Vp/Vs Ratio of Incoming Sediments Off Cascadia Subduction Zone From Analysis of Controlled-Source Multicomponent OBS Records

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DOI	10.1029/2019JB019239
	Vp/Vs Ratio of Incoming Sediments Off Cascadia Subduction Zone From Analysis of Controlled-Source Multicomponent OBS Records
	Zhu J.; Canales J.P.; Han S.; Carbotte S.M.; Arnulf A.; Nedimović M.R.
发表日期	2020
ISSN	21699313
卷号	125 期号:6
英文摘要	P-to-S-converted waves observed in controlled-source multicomponent ocean bottom seismometer (OBS) records were used to derive the Vp/Vs structure of Cascadia Basin sediments. We used P-to-S waves converted at the basement to derive an empirical function describing the average Vp/Vs of Cascadia sediments as a function of sediment thickness. We derived one-dimensional interval Vp/Vs functions from semblance velocity analysis of S-converted intrasediment and basement reflections, which we used to define an empirical Vp/Vs versus burial depth compaction trend. We find that seaward from the Cascadia deformation front, Vp/Vs structure offshore northern Oregon and Washington shows little variability along strike, while the structure of incoming sediments offshore central Oregon is more heterogeneous and includes intermediate-to-deep sediment layers of anomalously elevated Vp/Vs. These zones with elevated Vp/Vs are likely due to elevated pore fluid pressures, although layers of high sand content intercalated within a more clayey sedimentary sequence, and/or a higher content of coarser-grained clay minerals relative to finer-grained smectite could be contributing factors. We find that the proto-décollement offshore central Oregon develops within the incoming sediments at a low-permeability boundary that traps fluids in a stratigraphic level where fluid overpressure exceeds 50% of the differential pressure between the hydrostatic pressure and the lithostatic pressure. Incoming sediments with the highest estimated fluid overpressures occur offshore central Oregon where deformation of the accretionary prism is seaward vergent. Conversely, landward vergence offshore northern Oregon and Washington correlates with more moderate pore pressures and laterally homogeneous Vp/Vs functions of Cascadia Basin sediments. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Cascadia; Juan de Fuca plate; ocean bottom seismometer; sediments; Vp/Vs
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/187809
作者单位	Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, United States; Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, United States; Department of Earth Sciences, Dalhousie University, Halifax, NS, Canada
推荐引用方式 GB/T 7714	Zhu J.,Canales J.P.,Han S.,et al. Vp/Vs Ratio of Incoming Sediments Off Cascadia Subduction Zone From Analysis of Controlled-Source Multicomponent OBS Records[J],2020,125(6).
APA	Zhu J.,Canales J.P.,Han S.,Carbotte S.M.,Arnulf A.,&Nedimović M.R..(2020).Vp/Vs Ratio of Incoming Sediments Off Cascadia Subduction Zone From Analysis of Controlled-Source Multicomponent OBS Records.Journal of Geophysical Research: Solid Earth,125(6).
MLA	Zhu J.,et al."Vp/Vs Ratio of Incoming Sediments Off Cascadia Subduction Zone From Analysis of Controlled-Source Multicomponent OBS Records".Journal of Geophysical Research: Solid Earth 125.6(2020).