刘兵兵^1,2,,
黄晓葛^1,,,
李娴^1,2,
陈祖安¹
1. 中国科学院地质与地球物理研究所, 地球与行星物理院重点实验室, 北京 100029
2. 中国科学院大学, 北京 100049

基金项目: 国家自然科学基金项目（41774096，41574089，41174074）资助


详细信息

作者简介: 刘兵兵, 男, 硕士研究生, 主要从事矿物物理研究.E-mail:liu183409520@126.com

通讯作者: 黄晓葛, 女, 副研, 主要从事岩石物理研究.E-mail:xghuang@mail.iggcas.ac.cn

中图分类号: P315

收稿日期:2018-04-13
修回日期:2018-06-12
上线日期:2019-02-15

The influences of carbonate melt on the electrical conductivity for pyrolite at high temperature and high pressure

LIU BingBing^1,2,,
HUANG XiaoGe^1,,,
LI Xian^1,2,
CHEN ZuAn¹
1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2. University of Chinese Academy of Sciences, Beijing 100049, China


More Information

Corresponding author: HUANG XiaoGe,E-mail:xghuang@mail.iggcas.ac.cn

MSC: P315

--> Received Date: 13 April 2018
Revised Date: 12 June 2018
Available Online: 15 February 2019


摘要
摘要:为了观测含碳酸盐地幔岩部分熔融过程中电导率的变化，厘清碳酸盐熔体在金伯利岩岩浆形成过程中所起的作用，并探讨Slave克拉通中部Lac de Gras地区约80~120 km深处的高导成因，我们利用DS 3600 t六面顶压机和Solartron 1260阻抗/增益-相位分析仪在1.0~3.0 GPa、673~1873 K温压条件下分别测量了含碳酸钠（Na₂CO₃）、碳酸钙（CaCO₃）和大洋中脊玄武岩（MORB）的地幔岩样品的电导率.实验结果表明，地幔岩样品的电导率主要受到温度和组分的影响，而压力对其影响较小.在温度低于1023 K时，含Na₂CO₃地幔岩样品的电导率明显高于含同比重CaCO₃和MORB的；温度达到1023 K时，含Na₂CO₃地幔岩样品开始熔融；但在之后的200 K温度区间内，该部分熔融样品的电导率随温度的增加几乎不发生变化.这一现象或许揭示：地幔深部的碳酸质岩浆在快速上升过程中会同化吸收岩石圈地幔中的斜方辉石（Opx），进而形成金伯利岩岩浆，期间岩浆的电导率几乎不发生变化.含CaCO₃和MORB的地幔岩样品分别在1723 K和1423 K开始熔融，其部分熔融样品的电导率随温度的增加而快速增加.依据前人的研究结果和我们的实验结果，我们认为可以用含碳酸盐的部分熔融样品来解释Slave克拉通中部Lac de Gras地区约80~120 km深处的异常高导现象，并推测熔体中碳酸盐的熔体比例小于2 wt.%.
关键词: 电导率/
碳酸盐熔体/
地幔岩/
金伯利岩岩浆

Abstract:In order to obtain the electrical conductivity of partially molten pyrolite with carbonate and make clear the causes of formation of kimberlite magma and high conductivity zone at depth of about 80~120 km of Lac de Gras area in Central Slave Craton, we measured the electrical conductivity on pyrolite with carbonate melt at pressure of 1.0~3.0 GPa, temperature of 673~1873 K and frequency ranges of 10^-1~10⁶ Hz using Solartron-1260 impedance/Gain-Phase analyzer with DS 3600 t multi-anvil apparatus. The experimental results show that electrical conductivity of partial melting samples is mainly affected by temperature and compositions. The electrical conductivities of samples containing Na₂CO₃ are significantly higher than those of other samples containing CaCO₃ and MORB below 1023 K. The electrical conductivities of partially molten Na₂CO₃-bearing pyrolite hardly increase when increasing temperature at 1073~1273 K. It reveals that carbonated silicate melt has constant electrical conductivity during the formation of kimberlite magma. According to previous experimental data, the high conductivity phenomenon in Lac de Gras area in Central Slave Craton at about 80~120 km may be explained by partially molten pyrolite containing carbonated silicate melt. It is speculated that less than 2 wt.% carbonate melts occur in the kimberlite magma.
Key words:Electrical conductivity/
Carbonate melt/
Pyrolite/
Kimberlite magma



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