水对上地幔电性结构的影响  

Effect of Water on the Upper Mantle Electrical Structure

作　　者：张云霞[1] 胡祥云[1] 高锐[2] 王海燕[2] 万芬[1] 余毅[1] 李建慧[1] 蔡建超[1] 

机构地区：[1]中国地质大学电磁探测与深部资源研究中心,武汉430074 [2]中国地质科学院地质研究所岩石圈研究中心,北京100037

出　　处：《地质科技情报》2014年第3期51-56,共6页Geological Science and Technology Information

基　　金：国家深部探测专项(Sinoprobe-02-01);国家重点基础研究发展计划项目(2013CB733200);国家自然科学基金项目(41274077)

摘　　要：上地幔可以存储大量的水，水能够极大地增强地幔矿物的电导率。在实验室高温高压条件下获得了含水和不含水矿物电导率不同的结论，有必要广泛开展含水矿物电导率实验研究。基于最新实验结果，充分考虑上地幔热力学条件，矿物体积随深度变化和矿物间水分配情况，对2个研究小组上地幔4种主要矿物实验室电导率结果采用平均方法建立随水含量变化的上地幔电导率-深度曲线，并与实测地球物理模型进行了对比。研究表明，水能够极大地影响上地幔的电性结构，推测上地幔平均水质量分数为0．01％，位于地球化学方法推断的上地幔水质量分数范围（50×10^-6～200×10^-6）。海洋上地幔软流圈高电导率异常很可能是碳酸盐熔体、硅酸盐熔体及水共同作用的结果。The upper mantle can store large amounts of water that can greatly enhance the electrical conductivity of hydrous minerals. Given the different conclusions on the electrical conductivity of minerals un- der dry and hydrous conditions, an extensive experimental study on the conductivity of hydrous minerals is required. Based on the latest experimental data on the four main minerals in the upper mantle from the two research groups, laboratory-based conductivity-depth profiles were constructed as a function of water con tent after taking full account of the thermodynamic conditions, mineral volume changes, and hydrogen partitioning. A comparison of our conductivity-depth profiles with geophysical observations indicates that water can greatly influence the electrical structure of the upper mantle, the average water content in the upper mantle is 0.01%, which corresponds to a range of water content inferred from geochemical studies. The conductivity anomalies in the asthenosphere likely represent silicate melt, carbonate melt, and hydrated peridotite.

关 键 词：电导率 水 上地幔 电性结构 部分熔融 

分 类 号：P574.19[天文地球—矿物学]