Anhydrite solubility in low-density hydrothermal fluids: Experimental measurements and thermodynamic calculations
Anhydrite solubility in low-density hydrothermal fluids: Experimental measurements and thermodynamic calculations
复制标题
硬石膏在低密度热液中的溶解度：实验测量和热力学计算
DOI：
10.1016/j.chemgeo.2019.06.018
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发表时间：
2019
期刊：
影响因子：
3.9
通讯作者：
W. Seyfried
中科院分区：
文献类型：
--
作者：
Peter P. Scheuermann;B. Tutolo;W. Seyfried
流体-矿物平衡的热力学预测极大地扩展了我们在地质系统中测试质量和传热假设的能力。在许多情况下，热力学模型的成功发展在很大程度上依赖于实验测量。由于缺乏低密度热液流体的实验数据，因此无法在与大洋中脊热液系统相关的最极端温度-压力条件下计算流体-矿物平衡。本研究比较了低密度NaCl-H2O流体（410 °C， 25-32 MPa和450 °C， 363 - 50 MPa）中新获得的硬石膏溶解度测量结果与新的热力学计算结果。为了解决在实验的精确温度-压力条件下缺乏平衡常数的问题，数据从参考条件作为水密度对数的线性函数外推。几个溶解度计算进行了不同的选择的水形态和活度系数模型。实验观察和热力学预测之间总体上很一致，这表明了准确评估低密度流体中流体-矿物平衡的潜力。然而，物种形成的计算并不是唯一的，这突出了水中物种形成和活度系数计算的不确定性，这需要进一步的研究。这项研究代表了增加温度-压力条件的重要的第一步，在这种条件下，流体-矿物平衡的热力学计算是可能的，对理解海底热液系统的质量和传热具有重要意义。
Thermodynamic predictions of fluid-mineral equilibria significantly expand our ability to test hypotheses regarding mass and heat transfer in geological systems. In many cases, successful development of thermodynamic models relies heavily on experimental measurements. A dearth of experimental data in low-density hydrothermal fluids has prevented calculation of fluid-mineral equilibria at the most extreme temperature-pressure conditions associated with mid-ocean ridge hydrothermal systems. This study compares newly attained anhydrite solubility measurements in low-density NaCl-H2O fluids (410 °C, 25–32 MPa and 450 °C, 36.3–50 MPa) with novel thermodynamic calculations. To address the lack of equilibrium constants at the precise temperature-pressure conditions of the experiments, data are extrapolated from reference conditions as a linear function of the logarithm of water density. Several solubility calculations are performed that vary in the choice of aqueous speciation and activity coefficient model. There is overall good agreement between experimental observations and thermodynamic predictions, indicating the potential for accurate assessment of fluid-mineral equilibria in low-density fluids. However, speciation calculations are non-unique, highlighting uncertainties in aqueous speciation and calculation of activity coefficients that will require further examination. This study represents an important first step in increasing the temperature-pressure conditions over which thermodynamic calculations of fluid-mineral equilibria are possible, with important implications for understanding mass and heat transfer in submarine hydrothermal systems.
影响因子：
5
作者：
D. Syverson;D. Syverson;D. Syverson;Peter P. Scheuermann;J. Higgins;N. Pester;W. Seyfried
通讯作者：
D. Syverson;D. Syverson;D. Syverson;Peter P. Scheuermann;J. Higgins;N. Pester;W. Seyfried