DOI: 10.1016/j.epsl.2019.115922
论文题名: Temperature-enhanced electrical conductivity anisotropy in partially molten peridotite under shear deformation
作者: Zhang B. ; Yoshino T.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 530 语种: 英语
中文关键词: 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165378
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
Zhang B.,Yoshino T.. Temperature-enhanced electrical conductivity anisotropy in partially molten peridotite under shear deformation[J]. Earth and Planetary Science Letters,2020-01-01,530