The effect of chemical composition and oxygen fugacity on the electrical conductivity of dry and hydrous garnet at high temperatures and pressures

	The effect of chemical composition and oxygen fugacity on the electrical conductivity of dry and hydrous garnet at high temperatures and pressures
	Lidong Dai; Heping Li; Haiying Hu; Shuangming Shan; Jianjun Jiang; Keshi Hui
	2012
发表期刊	Contributions to Mineralogy and Petrology
卷号	163 期号:4 页码:689-700
摘要	The in situ electrical conductivity of hydrous garnet samples (Py(20)Alm(76)Grs(4)-Py(73)Alm(14)Grs(13)) was determined at pressures of 1.0-4.0 GPa and temperatures of 873-1273 K in the YJ-3000t apparatus using a Solartron-1260 impedance/gain-phase analyzer for various chemical compositions and oxygen fugacities. The oxygen fugacity was controlled by five solid-state oxygen buffers (Fe2O3 + Fe3O4, Ni + NiO, Fe + Fe3O4, Fe + FeO, and Mo + MoO2). Experimental results indicate that within a frequency range from 10(-2) to 10(6) Hz, electrical conductivity is strongly dependent on signal frequency. Electrical conductivity shows an Arrhenius increase with temperature. At 2.0 GPa, the electrical conductivity of anhydrous garnet single crystals with various chemical compositions (Py(20)Alm(76)Grs(4), Py(30)Alm(67)Grs(3), Py(56)Alm(43)Grs(1), and Py(73)Alm(14)Grs(13)) decreases with increasing pyrope component (Py). With increasing oxygen fugacity, the electrical conductivity of dry Py(73)Alm(14)Grs(13) garnet single crystal shows an increase, whereas that of a hydrous sample with 465 ppm water shows a decrease, both following a power law (exponents of 0.061 and -0.071, respectively). With increasing pressure, the electrical conductivity of this hydrous garnet increases, along with the pre-exponential factors, and the activation energy and activation volume of hydrous samples are 0.7731 +/- 0.0041 eV and -1.4 +/- 0.15 cm(3)/mol, respectively. The results show that small hopping polarons (Fe-Mg(center dot)) and protons (H-center dot) are the dominant conduction mechanisms for dry and wet garnet single crystals, respectively. Based on these results and the effective medium theory, we established the electrical conductivity of an eclogite model with different mineral contents at high temperatures and high pressures, thereby providing constraints on the inversion of field magnetotelluric sounding results in future studies.
关键词	Oxygen Fugacity Chemical Composition Electrical Conductivity Garnet High Temperature And High Pressure
学科领域	地球深部物质与流体作用地球化学
收录类别	SCI
语种	英语
文献类型	期刊论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/4861
专题	地球内部物质高温高压实验室_地球内部物质高温高压实验室_期刊论文
推荐引用方式 GB/T 7714	Lidong Dai,Heping Li,Haiying Hu,et al. The effect of chemical composition and oxygen fugacity on the electrical conductivity of dry and hydrous garnet at high temperatures and pressures[J]. Contributions to Mineralogy and Petrology,2012,163(4):689-700.
APA	Lidong Dai,Heping Li,Haiying Hu,Shuangming Shan,Jianjun Jiang,&Keshi Hui.(2012).The effect of chemical composition and oxygen fugacity on the electrical conductivity of dry and hydrous garnet at high temperatures and pressures.Contributions to Mineralogy and Petrology,163(4),689-700.
MLA	Lidong Dai,et al."The effect of chemical composition and oxygen fugacity on the electrical conductivity of dry and hydrous garnet at high temperatures and pressures".Contributions to Mineralogy and Petrology 163.4(2012):689-700.

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