Electrical conductivity and dissociation of fluids in crust and mantle

测量了H_2 O-NaCl体系中流体的电导率，电导率为1GPa和600 ℃。这些数据是该系统中可用电导率数据的压力范围的两倍多。开发了一个简单的数值模型，可以预测整个地壳和浅上地幔中含盐流体的电导率。俯冲带弧前区域电导率升高的原因是，不超过1%的盐水形成了连续的薄膜或网络。目前的扩展提案要求提供资金，将NaCl-H2O、KCl-H2O、HCl-H2O和NaOH-H2O系统的电导率测量扩展到3 GPa和1000 ℃。这些数据将提供坚定的约束溶解物种的解离常数和上地幔流体的pH值，并允许测试各种预测的热力学模型。此外，这些数据将允许模拟复杂流体的导电性，这将允许区分热液系统和火山下方的岩浆房，从而有助于火山风险评估。

The electrical conductivity of fluids in the system H2O-NaCl has been measured to 1 GPa and 600 ˚C. These data more than double the pressure range of available conductivity data in this system. A simple numerical model was developed that allows predicting the conductivity of saline fluids in the entire crust and the shallow upper mantle. The elevated conductivity in the forearc region of subduction zones can be explained by not more than 1 % of a saline fluid forming a continuous film or network. The present extension proposal request funding for extending the conductivity measurements in the systems NaCl-H2O, KCl-H2O, HCl-H2O, and NaOH-H2O to 3 GPa and 1000 ˚C. These data would provide firm constraints on dissociation constants of dissolved species and of the pH of fluids in the upper mantle and would allow testing various predictions by thermodynamic models. Moreover, the data would allow modeling the conductivity of complex fluids, which would allow distinguishing hydrothermal systems from magma chambers below volcanoes and therefore aid in volcanic risk assessment.