Can in situ measurements of mantle electrical conductivity be used to infer properties of partial melts
Can in situ measurements of mantle electrical conductivity be used to infer properties of partial melts
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地幔电导率的原位测量能否用于推断部分熔体的性质
DOI：
10.1029/2002jb001899
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发表时间：
2003
影响因子：
--
通讯作者：
M. Ducea
中科院分区：
文献类型：
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作者：
Stephen K. Park;M. Ducea
[1]大地电磁测量和岩石学分析的晚第四纪橄榄岩捕虏体从南部山脉内华达州的体积电导率的限制允许评估模型通常用于将电导率的物理和化学状态的上地幔。在这些模型中，两个导电熔体（玄武岩和硫化物）嵌入在电阻矩阵。硫化物量（0.06-0.4%）和体积电导率（0.03-0.1 S/m）的限制对熔体之间的互连程度产生了约束。由于硫化物熔体的导电性很强，即使是一小部分连接良好的熔体也会导致体积电导率大于0.1 S/m。类似地，完全断开的熔体导致体积电导率远小于0.03 S/m。唯一的模型，匹配的体积电导率和硫化物边界由一小部分（<1%）互连的玄武岩熔体与不连续的硫化物相。在实验室实验中观察到这样的纹理与大得多的硫化物熔体分数，但还没有报告为小熔体分数。Hashin-Shtrikman模型的变体和由级联Hashin-Shtrikman计算组成的混合模型成功地匹配了大地电磁和岩石学约束。通过适当模拟熔体连通性的模型，我们认为电导率可用于推断地幔中的原位熔体性质。
[1] Constraints on bulk conductivity from magnetotelluric measurements and petrological analyses of late Quaternary peridotite xenoliths from the southern Sierra Nevada allow evaluation of models commonly used to relate electrical conductivity to the physical and chemical state of the upper mantle. In these models, two conductive melts (basalt and sulfide) are embedded in a resistive matrix. Bounds on the amount of sulfide (0.06–0.4%) and the bulk conductivity (0.03–0.1 S/m) place constraints on the degree of interconnection between the melts. Because the sulfide melt is very conductive, even a small fraction of well-connected melt results in a bulk conductivity larger than 0.1 S/m. Similarly, completely disconnected melts result in bulk conductivities much less than 0.03 S/m. The only models which matched both the bulk conductivity and sulfide bounds consisted of a small fraction (<1%) interconnected basalt melt with a discontinuous sulfide phase. Such a texture is observed in laboratory experiments with much larger sulfide melt fractions, but has not been reported for small melt fractions. A variant of the Hashin-Shtrikman model and a hybrid model consisting of cascaded Hashin-Shtrikman calculations were successful in matching the magnetotelluric and petrologic constraints. With a model that appropriately simulates the melt interconnectivity, we suggest that electrical conductivity may be used to infer in situ melt properties in the mantle.