DOI: 10.1016/j.epsl.2018.04.056
Scopus记录号: 2-s2.0-85046870274
论文题名: Constraints on the presence of post-perovskite in Earth's lowermost mantle from tomographic-geodynamic model comparisons
作者: Koelemeijer P. ; Schuberth B.S.A. ; Davies D.R. ; Deuss A. ; Ritsema J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 494 起始页码: 226
结束页码: 238
语种: 英语
英文关键词: composition of the mantle
; geodynamic modelling
; mineral physics
; seismic tomography
; tomographic filtering
Scopus关键词: Acoustic wave velocity
; Geodynamics
; Perovskite
; Seismic waves
; Seismology
; Shear waves
; Table lookup
; Wave propagation
; Chemical heterogeneities
; Composition of the mantles
; Compressional wave velocity
; Lower mantle tomographies
; Mineral physics
; Seismic tomography
; Seismic velocity structure
; Tomographic
; Shear flow
英文摘要: Lower mantle tomography models consistently feature an increase in the ratio of shear-wave velocity (VS) to compressional-wave velocity (VP) variations and a negative correlation between shear-wave and bulk-sound velocity (VC) variations. These seismic characteristics, also observed in the recent SP12RTS model, have been interpreted to be indicative of large-scale chemical variations. Other explanations, such as the lower mantle post-perovskite (pPv) phase, which would not require chemical heterogeneity, have been explored less. Constraining the origin of these seismic features is important, as geodynamic simulations predict a fundamentally different style of mantle convection under both scenarios. Here, we investigate to what extent the presence of pPv explains the observed high VS/VP ratios and negative VS–VC correlation globally. We compare the statistical properties of SP12RTS with the statistics of synthetic tomography models, derived from both thermal and thermochemical models of 3-D global mantle convection. We convert the temperature fields of these models into seismic velocity structures using mineral physics lookup tables with and without pPv. We account for the limited tomographic resolution of SP12RTS using its resolution operator for both VS and VP structures. This allows for direct comparisons of the resulting velocity ratios and correlations. Although the tomographic filtering significantly affects the synthetic tomography images, we demonstrate that the effect of pPv remains evident in the ratios and correlations of seismic velocities. We find that lateral variations in the presence of pPv have a dominant influence on the VS/VP ratio and VS–VC correlation, which are thus unsuitable measures to constrain the presence of large-scale chemical variations in the lowermost mantle. To explain the decrease in the VS/VP ratio of SP12RTS close to the CMB, our results favour a pPv-bearing CMB region, which has implications for the stability field of pPv in the Earth's mantle. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109838
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: University College Oxford, Department of Earth Sciences, University of Oxford, Oxford, United Kingdom; Institute of Geophysics, Department of Earth Sciences, ETH Zürich, Zurich, Switzerland; Geophysics Section, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany; The Research School of Earth Sciences, Australian National University, Canberra, Australia; Department of Earth Sciences, Utrecht University, Utrecht, Netherlands; Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, United States
Recommended Citation:
Koelemeijer P.,Schuberth B.S.A.,Davies D.R.,et al. Constraints on the presence of post-perovskite in Earth's lowermost mantle from tomographic-geodynamic model comparisons[J]. Earth and Planetary Science Letters,2018-01-01,494