气候变化领域集成服务门户(CCPortal): Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures

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DOI	10.1029/2020JB021325
	Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures
	Hansen L.N.; Wallis D.; Breithaupt T.; Thom C.A.; Kempton I.
发表日期	2021
ISSN	21699313
卷号	126 期号:5
英文摘要	Transient creep occurs during geodynamic processes that impose stress changes on rocks at high temperatures. The transient is manifested as evolution in the viscosity of the rocks until steady-state flow is achieved. Although several phenomenological models of transient creep in rocks have been proposed, the dominant microphysical processes that control such behavior remain poorly constrained. To identify the intragranular processes that contribute to transient creep of olivine, we performed stress-reduction tests on single crystals of olivine at temperatures of 1,250°C–1,300°C. In these experiments, samples undergo time-dependent reverse strain after the stress reduction. The magnitude of reverse strain is ∼10−3 and increases with increasing magnitude of the stress reduction. High-angular resolution electron backscatter diffraction analyses of deformed material reveal lattice curvature and heterogeneous stresses associated with the dominant slip system. The mechanical and microstructural data are consistent with transient creep of the single crystals arising from accumulation and release of backstresses among dislocations. These results allow the dislocation-glide component of creep at high temperatures to be isolated, and we use these data to calibrate a flow law for olivine to describe the glide component of creep over a wide temperature range. We argue that this flow law can be used to estimate both transient creep and steady-state viscosities of olivine, with the transient evolution controlled by the evolution of the backstress. This model is able to predict variability in the style of transient (normal vs. inverse) and the load-relaxation response observed in previous work. © 2021. American Geophysical Union. All Rights Reserved.
英文关键词	Backstress; dislocation creep; dislocation interactions; mantle viscosity; olivine; stress-reduction tests; transient creep
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187171
作者单位	Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, United States; Department of Earth Sciences, Utrecht University, Utrecht, Netherlands; Now at Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom; Department of Earth Sciences, University of Oxford, Oxford, United Kingdom
推荐引用方式 GB/T 7714	Hansen L.N.,Wallis D.,Breithaupt T.,et al. Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures[J],2021,126(5).
APA	Hansen L.N.,Wallis D.,Breithaupt T.,Thom C.A.,&Kempton I..(2021).Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures.Journal of Geophysical Research: Solid Earth,126(5).
MLA	Hansen L.N.,et al."Dislocation Creep of Olivine: Backstress Evolution Controls Transient Creep at High Temperatures".Journal of Geophysical Research: Solid Earth 126.5(2021).