DOI: 10.1016/j.epsl.2021.116783
论文题名: Crustal attenuation beneath western North America: Implications for slab subduction, terrane accretion and arc magmatism of the Cascades
作者: Chen Y. ; Gu Y.J. ; Mohammed F. ; Wang J. ; Sacchi M.D. ; Wang R. ; Nguyen B.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 560 语种: 英语
中文关键词: Cascadia subduction zone
; continental crust
; Lg-wave attenuation tomography
; Siletzia terrane
; western North America
英文关键词: Geology
; Mathematical models
; Attenuation characteristics
; Crustal attenuation
; Heterogeneous structures
; Seismic attenuation
; Seismic velocities
; Snake river plains
; Spatial correlations
; Structural boundary
; Seismology
; continental crust
; data set
; seismic tomography
; seismic velocity
; seismic wave
; slab
; subduction zone
; wave attenuation
; Cascadia Subduction Zone
; North America
; Pacific Ocean
; Cascadia
英文摘要: The western margin of the North American continent is a composite of diverse crustal domains featuring ancestral cratons, the Cordilleran terranes and the subducting Cascadia slab. Their existence and spatial extent have been largely inferred from seismic imaging, which is highly sensitive to variations in both crustal seismic velocity and attenuation structures. In this study, we improve upon existing, yet relatively limited, knowledge of crustal attenuation by developing a new Lg-wave attenuation (Q0) model. Benefiting from a comprehensive data set from dense seismic networks in Canada and the United States, our model reveals a clear transition from the low-attenuation (Q0>450) Canadian Shield to the highly-attenuated (Q0<150) crust near the Cascade arc. In the former region, the low-attenuation structures agree well with the distribution of thick, high-velocity crust in the Cordilleran foreland, suggesting dominant effects of elastic properties such as scattering and geometry of the crustal waveguide on the attenuation characteristics of stable cratons. On the other hand, we observe strong crustal attenuations in magmatically active areas including the Cascade arc and the Yellowstone-Snake River Plain volcanic province. The excellent spatial correlation between the high-attenuation Cascades and the surface projection of the subducting slabs further suggests a possible role of slab dehydration in increasing the fluid content of the overlying continental crust and modifying seismic attenuation. The sharp termination of the highly-attenuated crust forms a structural boundary in the Cascade back-arc that likely marks the eastern subsurface limit of the Siletzia terrane. The close spatial affinity of this boundary to the isotopic ratio lineament of 87Sr/86Sr = 0.706, which is the suggested ancestral continental margin, highlights the distinctive crustal types and/or heterogeneous structures between young accreted terranes and ancient cratons. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165432
Appears in Collections: 气候变化与战略
There are no files associated with this item.
作者单位: Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province, School of Earth Sciences, Zhejiang University, Hangzhou, 310027, China; Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada; Department of Earth & Planetary Sciences, University of New Mexico, Albuquerque, NM, United States
Recommended Citation:
Chen Y.,Gu Y.J.,Mohammed F.,et al. Crustal attenuation beneath western North America: Implications for slab subduction, terrane accretion and arc magmatism of the Cascades[J]. Earth and Planetary Science Letters,2021-01-01,560