DOI: 10.1016/j.epsl.2020.116142
论文题名: Investigating ultra-low velocity zones in the southern hemisphere using an Antarctic dataset
作者: Hansen S.E. ; Carson S.E. ; Garnero E.J. ; Rost S. ; Yu S.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 536 语种: 英语
中文关键词: ScP
; southern hemisphere
; ultra-low velocity zones
英文关键词: Seismology
; Structural geology
; Uncertainty analysis
; Velocity
; Core-mantle boundary
; Mantle convection
; Model uncertainties
; Seismic coverage
; Shear velocities
; Southern Hemisphere
; Synthetic seismogram
; Ultralow velocity zone
; Shear flow
; core-mantle boundary
; data set
; lower mantle
; mantle convection
; seismic data
; seismic reflection
; seismic velocity
; seismicity
; seismogram
; Southern Hemisphere
; Antarctica
; New Zealand
; Southern Ocean
; Transantarctic Mountains
; Weddell Sea
英文摘要: Given limited seismic coverage of the lowermost mantle, less than one-fifth of the core-mantle boundary (CMB) has been surveyed for the presence of ultra-low velocity zones (ULVZs). Investigations that sample the CMB with new geometries are therefore important to further our understanding of ULVZ origins and their potential connection to other deep Earth processes. Using core-reflected ScP waves recorded by the recently deployed Transantarctic Mountains Northern Network in Antarctica, the current study aims to expand ULVZ investigations in the southern hemisphere. Our dataset samples the CMB in the vicinity of New Zealand, providing coverage between an area to the northeast, where ULVZ structure has been previously identified, and another region to the south, where prior evidence for a ULVZ was inconclusive. This area is of particular interest because the data sample across the boundary of the Pacific Large Low Shear Velocity Province (LLSVP). The Weddell Sea region near Antarctica is also well sampled, providing new information on a region that has not been previously studied. A correlative scheme between a large database of 1-D synthetic seismograms and the observed ScP data demonstrates that ULVZs are required in both study regions. Modeling uncertainties limit our ability to definitively define ULVZ characteristics but also likely indicate more complex 3-D structure. Given that ULVZs are detected within, along the edge of, and far from the Pacific LLSVP, our results support the hypothesis that ULVZs are compositionally distinct from the surrounding mantle and are not solely related to partial melt. ULVZs may be ubiquitous along the CMB; however, they may be thinner in many regions than can be resolved by current methods. Mantle convection currents may sweep the ULVZs into thicker piles in some areas, pushing these anomalies toward the boundaries of LLSVPs. © 2020 The Author(s) Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165008
Appears in Collections: 气候变化与战略
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作者单位: Department of Geological Sciences, The University of Alabama, United States; School of Earth and Space Exploration, Arizona State University, United States; School of Earth and Environment, University of Leeds, Ireland
Recommended Citation:
Hansen S.E.,Carson S.E.,Garnero E.J.,et al. Investigating ultra-low velocity zones in the southern hemisphere using an Antarctic dataset[J]. Earth and Planetary Science Letters,2020-01-01,536