DOI: 10.1016/j.epsl.2020.116160
论文题名: Variable dynamic styles of primordial heterogeneity preservation in the Earth's lower mantle
作者: Gülcher A.J.P. ; Gebhardt D.J. ; Ballmer M.D. ; Tackley P.J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 536 语种: 英语
中文关键词: compositional heterogeneity
; Earth structure
; mantle composition
; mantle dynamics
; primitive material
; primordial domains
英文关键词: Dynamics
; Geochemistry
; Geophysics
; Long Term Evolution (LTE)
; Mass transfer
; Mixing
; Planets
; Silica
; Structural geology
; Topography
; Compositional heterogeneity
; Earth structures
; Mantle composition
; Mantle dynamics
; Primordial domains
; Earth (planet)
; heterogeneity
; lower mantle
; mantle source
; mantle structure
; numerical model
; structural geology
; tectonic evolution
; tectonic setting
; two-dimensional modeling
英文摘要: The evolution of the system Earth is critically influenced by the long-term dynamics, composition and structure of the mantle. While cosmochemical and geochemical constraints indicate that the lower mantle hosts an ancient primordial reservoir that may be enriched in SiO2 with respect to the upper mantle, geophysical observations and models point to efficient mass transfer and convective mixing across the entire mantle. Recent hypotheses of primordial-material preservation in a convecting mantle involve delayed mixing of intrinsically dense and/or intrinsically strong heterogeneity. Yet, the effects of composition-dependent rheology and density upon heterogeneity preservation and the dynamics of mantle mixing remain poorly understood. Here, we present two-dimensional numerical models in spherical geometry, investigating the preservation styles of primordial material as a function of its physical properties (i.e., viscosity and density contrasts). We establish multiple regimes of primordial-material preservation that can occur in terrestrial planets. These include (1) efficient mixing, (2) double-layered convection with or without topography, and (3) variable styles of partial heterogeneity preservation (e.g., as diffuse domains, piles or viscous blobs in the lower mantle). Some of these regimes are here characterised for the first time, and all regimes are put into context with each other as a function of model parameters. The viscous-blobs and diffuse-domains regimes can reconcile the preservation of primordial domains in a convecting mantle, potentially resolving the discrepancy between geochemical and geophysical constraints for planet Earth. Several, if not all, regimes characterised here may be relevant to understand the long-term evolution of terrestrial planets in general. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165002
Appears in Collections: 气候变化与战略
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作者单位: Institute of Geophysics, Department of Earth Sciences, ETH Zürich, Zürich, Switzerland; Department of Earth Sciences, University College London, London, United Kingdom; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
Recommended Citation:
Gülcher A.J.P.,Gebhardt D.J.,Ballmer M.D.,et al. Variable dynamic styles of primordial heterogeneity preservation in the Earth's lower mantle[J]. Earth and Planetary Science Letters,2020-01-01,536