DOI: 10.1016/j.epsl.2018.04.055
Scopus记录号: 2-s2.0-85046997050
论文题名: Inferring crustal viscosity from seismic velocity: Application to the lower crust of Southern California
作者: Shinevar W.J. ; Behn M.D. ; Hirth G. ; Jagoutz O.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 494 起始页码: 83
结束页码: 91
语种: 英语
英文关键词: composition
; lower crust
; rheology
; Southern California
; stress
; viscosity
Scopus关键词: Chemical analysis
; Elasticity
; Geodynamics
; Lithology
; Mica
; Quartz
; Rheology
; Seismic waves
; Shear waves
; Silicate minerals
; Strain rate
; Stresses
; Velocity
; Viscosity
; Compositional variation
; Crustal composition
; Geophysical observations
; Lower crust
; Orders of magnitude
; Southern California
; Three orders of magnitude
; Total variabilities
; Seismology
; lower crust
; P-wave
; rheology
; S-wave
; seismic data
; seismic velocity
; stress
; viscosity
; wave velocity
; California
; United States
; Calluna vulgaris
英文摘要: We investigate the role of composition on the viscosity of the lower crust through a joint inversion of seismic P-wave (Vp) and S-wave (Vs) velocities. We determine the efficacy of using seismic velocity to constrain viscosity, extending previous research demonstrating robust relationships between seismic velocity and crustal composition, as well as crustal composition and viscosity. First, we calculate equilibrium mineral assemblages and seismic velocities for a global compilation of crustal rocks at relevant pressures and temperatures. Second, we use a rheological mixing model that incorporates single-phase flow laws for major crust-forming minerals to calculate aggregate viscosity from predicted mineral assemblages. We find a robust correlation between crustal viscosity and Vp together with Vs in the α-quartz regime. Using seismic data, geodetic surface strain rates, and heat flow measurements from Southern California, our method predicts that lower crustal viscosity varies regionally by four orders of magnitude, and lower crustal stress varies by three orders of magnitude at 25 km depth. At least half of the total variability in stress can be attributed to composition, implying that regional lithology has a significant effect on lower crustal geodynamics. Finally, we use our method to predict the depth of the brittle–ductile transition and compare this to regional variations of the seismic–aseismic transition. The variations in the seismic–aseismic transition are not explained by the variations in our model rheology inferred from the geophysical observations. Thus, we conclude that fabric development, in conjunction with compositional variations (i.e., quartz and mica content), is required to explain the regional changes in the seismic–aseismic transition. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109855
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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Recommended Citation:
Shinevar W.J.,Behn M.D.,Hirth G.,et al. Inferring crustal viscosity from seismic velocity: Application to the lower crust of Southern California[J]. Earth and Planetary Science Letters,2018-01-01,494