气候变化领域集成服务门户(CCPortal): Subcretionary tectonics: Linking variability in the expression of subduction along the Cascadia forearc

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DOI	10.1016/j.epsl.2020.116724
	Subcretionary tectonics: Linking variability in the expression of subduction along the Cascadia forearc
	Delph J.R.; Thomas A.M.; Levander A.
发表日期	2021
ISSN	0012821X
卷号	556
英文摘要	A number of seismic and other geophysical phenomena exhibit significant lateral heterogeneity along the strike of the Cascadia forearc. Both the overriding and downgoing plate have been invoked to play the dominant role in controlling along-strike correlations between seismogenic behavior, potential field measurements, morphological/tectonic characteristics, and seismic structure; however, significant feedbacks likely exist between the two. In this study, we apply a 3D velocity correction to receiver function data and interpret the resulting discontinuity model alongside a recently published shear-wave velocity model to understand the possible causative relationships between correlative along-strike variations. Our discontinuity model indicates that the forearc crust thickens as it approaches the mantle wedge corner before progressively thinning toward the magmatic arc, likely due to the basal accretion of material from the downgoing plate to the overriding plate. In the northern and southern portions of the forearc, this “subcreted” material is characterized by thick (∼10 km) anomalously low shear-wave velocity zones. The thickness, high internal reflectivity, and low Bouguer gravity signatures associated with the low velocity zones likely indicate that this subcreted material is composed of dominantly (meta)sedimentary material that has been emplaced through successive subcretion events over geologic timescales. Furthermore, the anomalously low velocities and spatial correlation with high non-volcanic tremor (NVT) density and short slow slip recurrence intervals indicate that these regions are fluid-rich. While first-order variations in the fluids that control NVT and slow slip likely result from differences in the permeability of the downgoing slab as inferred from its stress state and the distribution of intraslab seismicity, these subcreted packages likely represent thick, vertically-impermeable regions in the lower crust that further accentuate this correlation. Variability in the amount of subcretion explains patterns of exhumation and uplift along the Cascadia margin and the resulting forearc topography over geologic timescales, and is likely controlled by some combination plate interface geometry/rheology and overriding plate architecture. © 2020 Elsevier B.V.
关键词	forearc structure orogenesis seismic imaging subduction underplating
英文关键词	Acoustic wave velocity; Percolation (fluids); Plates (structural components); Seismology; Shear waves; Topography; Wave propagation; Discontinuity model; Geophysical phenomena; Internal reflectivity; Lateral heterogeneity; Non-volcanic tremors; Recurrence intervals; Shear wave velocity models; Spatial correlations; Shear flow; discontinuity; forearc basin; orogeny; plate tectonics; S-wave; seismic velocity; subduction; underplating; Cascadia
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203067
作者单位	Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, 550 Stadium Mall Dr., West Lafayette, IN 47907, United States; Department of Earth Sciences, University of Oregon, 100 Cascade Hall, Eugene, OR 97403, United States; Department of Earth, Environmental and Planetary Sciences, Rice University, 6100 Main St., Houston, TX 77005, United States
推荐引用方式 GB/T 7714	Delph J.R.,Thomas A.M.,Levander A.. Subcretionary tectonics: Linking variability in the expression of subduction along the Cascadia forearc[J],2021,556.
APA	Delph J.R.,Thomas A.M.,&Levander A..(2021).Subcretionary tectonics: Linking variability in the expression of subduction along the Cascadia forearc.Earth and Planetary Science Letters,556.
MLA	Delph J.R.,et al."Subcretionary tectonics: Linking variability in the expression of subduction along the Cascadia forearc".Earth and Planetary Science Letters 556(2021).