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DOI	10.1016/j.epsl.2019.115922
	Temperature-enhanced electrical conductivity anisotropy in partially molten peridotite under shear deformation
	Zhang B.; Yoshino T.
发表日期	2020
ISSN	0012821X
卷号	530
英文摘要	The high conductivity anomalies observed in the oceanic asthenosphere have shown anisotropic signature parallel to the plate motion. Anisotropic alignment of partial melt has been considered to one of probable explanations for the observed anisotropic conductivity structure, but the effect of temperature on the distribution of melt, the composition of melt, and the magnitude of electrical anisotropy for partial molten peridotite is unknown under shear deformation. In this study, the electrical conductivity of partially molten peridotite (KLB-1) under shear deformation was measured at 1 GPa in a DIA type apparatus with a uniaxial deformation facility to provide new constraints on the anisotropic signature in the oceanic asthenosphere. The conductivity measurements were performed simultaneously in two directions of three principal axes: parallel and normal to the shear direction on the shear plane, and perpendicular to the shear plane, by using impedance spectroscopy at temperature ranges of 1483-1548 K. Our results indicate that the total melt fraction, the absolute conductivity values, and the magnitude of electrical anisotropy of partially molten peridotite increase with increasing temperature. Although the Na2O content varies widely at constant temperature in the recovered melt, very small changes of shear-parallel conductivities (σx) before and after shear deformation suggest that the electrical conductivity of partially molten peridotite is mainly controlled by temperature, rather than alkali content in partial melt. Microstructural observations of the recovered samples reveal that the development of conductivity anisotropy was caused by the realignment of melt pockets parallel to the shear direction, which forms two melt-rich regions. Furthermore, we estimate how much melt fraction is partitioned into melt-rich regions by calculating the area ratio of two melt-rich regions to the whole area. Our calculations show that once melt segregation occurs, more than 50% of the total melt fraction will partition into the melt-rich regions, and this proportion will continue to increase with the increase of temperature. This finding suggests that development of electrical anisotropy in partially molten peridotite under shear deformation will increase with increasing temperature, which may provide new constraints on interpretation of high conductivity anomalies observed in the oceanic asthenosphere. © 2019 Elsevier B.V.
关键词	electrical conductivity anisotropy high conductivity anomalies oceanic asthenosphere partial melt peridotite shear deformation
英文关键词	Anisotropy; Electric conductivity; Shear deformation; Sodium compounds; Temperature; Electrical conductivity; High conductivity; oceanic asthenosphere; Partial melt; peridotite; Shear flow; anisotropy; asthenosphere; deformation; electrical conductivity; partial melting; peridotite; shear; 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/203000
作者单位	Institute of Geology and Geophysics, School of Earth Sciences, Zhejiang University, Hangzhou, 310027, China; Key Laboratory for High-Temperature and High-Pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550081, China; Institute for Planetary Materials, Okayama University, Misasa, Tottori-ken 682-0193, Japan
推荐引用方式 GB/T 7714	Zhang B.,Yoshino T.. Temperature-enhanced electrical conductivity anisotropy in partially molten peridotite under shear deformation[J],2020,530.
APA	Zhang B.,&Yoshino T..(2020).Temperature-enhanced electrical conductivity anisotropy in partially molten peridotite under shear deformation.Earth and Planetary Science Letters,530.
MLA	Zhang B.,et al."Temperature-enhanced electrical conductivity anisotropy in partially molten peridotite under shear deformation".Earth and Planetary Science Letters 530(2020).