气候变化领域集成服务门户(CCPortal): Dislocation interactions during low-temperature plasticity of olivine and their impact on the evolution of lithospheric strength

CCPortal

DOI	10.1016/j.epsl.2020.116349
	Dislocation interactions during low-temperature plasticity of olivine and their impact on the evolution of lithospheric strength
	Wallis D.; Hansen L.N.; Kumamoto K.M.; Thom C.A.; Plümper O.; Ohl M.; Durham W.B.; Goldsby D.L.; Armstrong D.E.J.; Meyers C.D.; Goddard R.M.; Warren J.M.; Breithaupt T.; Drury M.R.; Wilkinson A.J.
发表日期	2020
ISSN	0012821X
卷号	543
英文摘要	The strength of the lithosphere is typically modelled based on constitutive equations for steady-state flow. However, strain hardening may cause significant evolution of strength in the colder load-bearing portion of the lithosphere. Recent rheological data from low-temperature deformation experiments on olivine suggest that strain hardening occurs due to the presence of temperature-independent back stresses generated by long-range elastic interactions among dislocations. These interpretations provided the basis for a flow law that incorporates hardening by the development of back stress. Here, we test this dislocation-interaction hypothesis by examining the microstructures of olivine samples deformed plastically at room temperature either in a deformation-DIA apparatus at differential stresses of ≤4.3GPa or in a nanoindenter at applied contact stresses of ≥10.2GPa. High-angular resolution electron backscatter diffraction maps reveal the presence of geometrically necessary dislocations with densities commonly above 1014m−2 and intragranular heterogeneities in residual stress on the order of 1 GPa in both sets of samples. Scanning transmission electron micrographs reveal straight dislocations aligned in slip bands and interacting with dislocations of other types that act as obstacles. The resulting accumulations of dislocations in their slip planes, and associated stress heterogeneities, are consistent with strain hardening resulting from long-range back-stresses acting among dislocations and thereby support the form of the flow law for low-temperature plasticity. Based on these observations, we predict that back stresses among dislocations will impart significant mechanical anisotropy to deformed lithosphere by enhancing or reducing the effective stress. Therefore, strain history, with associated microstructural and micromechanical evolution, is an important consideration for models of lithospheric strength. The microstructural observations also provide new criteria for identifying the operation of back-stress induced strain hardening in natural samples and therefore provide a means to test the applicability of the flow law for low-temperature plasticity. © 2020 The Author(s)
关键词	high-angular resolution electron backscatter diffraction (HR-EBSD)low-temperature plasticity microstructure olivine residual stress strain hardening
英文关键词	Constitutive equations; Deformation; Equations of state; Olivine; Plasticity; Strain hardening; Temperature; Electron back scatter diffraction; Geometrically necessary dislocations; High angular resolutions; Low temperature deformations; Low-temperature plasticity; Micro-structural observations; Temperature independents; Transmission electron micrograph; Stresses; backscatter; deformation; lithospheric structure; long range transport; low temperature; steady-state equilibrium; structural geology; temperature effect
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202953
作者单位	Department of Earth Sciences, Utrecht University, Utrecht, 3584 CB, Netherlands; Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, United Kingdom; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, United States; Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104, United States; Department of Materials, University of Oxford, Oxford, OX1 3PH, United Kingdom; Department of Earth Science, University of Minnesota-Twin Cities, Minneapolis, MN 55455, United States; Department of Earth Sciences, University of Delaware, Newark, DE 19716, United States
推荐引用方式 GB/T 7714	Wallis D.,Hansen L.N.,Kumamoto K.M.,et al. Dislocation interactions during low-temperature plasticity of olivine and their impact on the evolution of lithospheric strength[J],2020,543.
APA	Wallis D..,Hansen L.N..,Kumamoto K.M..,Thom C.A..,Plümper O..,...&Wilkinson A.J..(2020).Dislocation interactions during low-temperature plasticity of olivine and their impact on the evolution of lithospheric strength.Earth and Planetary Science Letters,543.
MLA	Wallis D.,et al."Dislocation interactions during low-temperature plasticity of olivine and their impact on the evolution of lithospheric strength".Earth and Planetary Science Letters 543(2020).