DOI: 10.1016/j.epsl.2018.06.003
Scopus记录号: 2-s2.0-85049325953
论文题名: Effect of dehydrogenation on the electrical conductivity of Fe-bearing amphibole: Implications for high conductivity anomalies in subduction zones and continental crust
作者: Hu H. ; Dai L. ; Li H. ; Sun W. ; Li B.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 498 起始页码: 27
结束页码: 37
语种: 英语
英文关键词: continental mid-crust and subduction zones
; dehydrogenation
; electrical conductivity
; Fe-bearing amphibole
; highly conductive anomalies
Scopus关键词: Dehydration
; Electric conductivity
; Infrared spectroscopy
; Activation enthalpies
; Electrical conductivity
; Electrical conductivity measurements
; highly conductive anomalies
; Impedance spectroscopy
; Magnetotelluric measurement
; Multi-anvil apparatus
; Subduction zones
; Dehydrogenation
; amphibole
; continental crust
; dehydration
; electrical conductivity
; hydrous mineral
; iron
; magnetotelluric method
; subduction zone
; Calluna vulgaris
英文摘要: Magnetotelluric measurements reveal the presence of high conductivity anomalies (up to ∼1 S/m) in both the forearc and backarc regions of subduction zones as well as the continental middle–lower crust. Such anomalies are commonly interpreted as a consequence of aqueous fluid released from the dehydration of hydrous minerals. Amphibole is an important constituent of the continental mid-crust and a major hydrous phase in subduction zones, such that its dehydration at high temperature has been suggested to provide a significant source of aqueous fluid. We performed electrical conductivity measurements of a natural Fe-bearing amphibole at 623–1173 K and 0.5–2.0 GPa using a multi-anvil apparatus and an impedance spectroscopy. Our results show that pressure has a very weak effect on conductivity compared with temperature. An abrupt variation of the impedance semicircular arc followed by a remarkable increase of electrical conductivity is observed at temperature of 843±20 K. However, the enhancement in conductivity is not attributed to conductive aqueous fluid but rather to amphibole oxidation–dehydrogenation, as confirmed by infrared spectroscopy and optical microscopy observations. A slight decrease in activation enthalpy from ∼0.80 eV to ∼0.70 eV suggests that the conduction mechanism does not change before and after dehydrogenation, and small polaron conduction (electron holes hopping between Fe2+ and Fe3+) is considered to dominate the conductivity of amphibole over the entire temperature range. Although amphibole dehydrogenation at high temperature cannot serve as a principal source of aqueous fluid, the enhanced electrical conductivity of amphibole after dehydrogenation is sufficient to account for the high conductivity anomalies observed in slab–mantle wedge interfaces and the continental lowermost mid-crust, particularly in local regions with high heat flow. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109749
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Key Laboratory for High-Temperature and High-Pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550002, China; Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794, United States; University of Chinese Academy of Sciences, Beijing, 100039, China
Recommended Citation:
Hu H.,Dai L.,Li H.,et al. Effect of dehydrogenation on the electrical conductivity of Fe-bearing amphibole: Implications for high conductivity anomalies in subduction zones and continental crust[J]. Earth and Planetary Science Letters,2018-01-01,498