Low frequency electrical response of polycrystalline olivine compacts: Grain boundary transport
Low frequency electrical response of polycrystalline olivine compacts: Grain boundary transport
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DOI：
10.1029/gl017i011p01985
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发表时间：
1990-10
影响因子：
5.2
通讯作者：
J. Tyburczy;J. Roberts
中科院分区：
文献类型：
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作者：
J. Tyburczy;J. Roberts
在频率范围104至10−4 Hz、温度800至1400°C、浮氏体-磁铁矿缓冲层的fO 2下，测定了圣卡洛斯橄榄石（晶粒尺寸75-180 μm）烧结多晶压块的复电阻抗。复平面图（Im Z与Re Z）显示晶粒内部和晶界电导率的单独影响。晶粒内部输运控制了102 Hz以上的响应，而晶界输运在102 Hz和10−2 Hz之间占主导地位。压坯的整体响应建模与等效电路，其中并联RC电路元件表示粮食内部和粮食响应的串联作用。体DC电导率低于单独的晶粒内部或晶粒边界电导率。利用晶粒-晶粒边界系统较低的体电导率反演大地电磁剖面，得出的上地幔温度估计值比基于单晶值的估计值高30至50°C。
The complex electrical impedance of sintered, polycrystalline compacts of San Carlos olivine (grain size 75–180 μm) has been determined over the frequency range 104 to 10−4 Hz, at temperatures between 800 and 1400°C, at the fO2 of the wustite-magnetite buffer. Complex plane plots (Im Z vs. Re Z) show separate effects of grain interior and grain boundary conductivity. Grain interior transport controls the response above ∼102 Hz, whereas grain boundary transport dominates between ∼102 and 10−2 Hz. Overall response of the compacts is modeled with an equivalent circuit in which parallel RC circuit elements representing grain interior and grain responses act in series. Bulk DC conductivity is lower than either grain interior or grain boundary conductivity alone. Inversion of magnetotelluric profiles that employ lower bulk conductivities of the grain interior-grain boundary system yield upper mantle temperature estimates 30 to 50°C higher than those based on single crystal values.