A Thermodynamic Model of Quartz Solubility in H<SUB>2O-CO₂-NaCl Systems up to 1000 ℃ and 1.5 GPa

详细信息   

• 责任者：Wei Qing(Key Laboratory of the Earth’ s Deep Interior ; Institute of Geology and Geophysics ; Chinese Academy of Sciences ; Beijing 100029 ; China) ; Duan ZhenHao
• 刊名：Acta Petrologica Sinica
• 出版年：2012
• 卷期：28(8)
• 关键词：高温高压实验 ; high temperature-high pressure experiment ; 石英 ; quartz ; 流体 ; fluids ; 溶解度 ; solubility
• 页码：p.2656-2666
• 图表：illus.,4 tables,59 refs.
• 分类号：0600
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

摘要

There are numerous experimental measurements of quartz solubility has been studied over a broad spectrum of aqueous fluid compositions and temperature-pressure range. Here, we proposed an equation, which can calculate the solubility of aqueous silica in H<SUB style="LINE-HEIGHT: 15px; WIDOWS: 2; TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(255,255,255); FONT-VARIANT: normal; FONT-STYLE: normal; TEXT-INDENT: 0px; FONT-FAMILY: ����,verdana; WHITE-SPACE: normal; ORPHANS: 2; LETTER-SPACING: normal; COLOR: rgb(0,0,0); FONT-WEIGHT: normal; WORD-SPACING: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px">2O-CO₂-NaCl fluid mixture at high temperatures and high pressures from 0~1000℃ and 0~1.5GPa, as follows: 
logm_SiO2=A(T)+B(T)·logM_H2O/V_H2O^*+C(t)·logx_H2O

    

Here A(T)、B(T) and C(t) are polynomials of temperatures T(K) and t(℃),x_H2O and V_H2O^* stand for the mole fraction and effective partial molar volume of H₂O in fluid, respectively. The value of V_H2O^* is calculated from the relation V_mix=x_HOV_H2O^*+Σx_sV_s, where V_mix represent the molar volume of the fluid mixture, which is

    

 

    

calculated from the recent model of Mao et al.(2010), x_s and V_s denote the mole fraction and the intrinsic volume of the solute, respectively. Values V_CO2=29.9cm³/mol and V_NaCl=30.8cm³/mol were adopted by this

    

 

    

thermodynamic model. The accuracy of our model is better than previous models, and our model is able to predict the solubility of quartz over a much wider T-P-x_s conditions relevant to the deep crust, so that it could be used to evaluate aqueous silica transport in Barrovian metamorphic belts and subduction zones and so on. In addition, our model is helpful to establish quartz geothermometer, discover the formation mechanics of deposits relevant to the quartz veins. Online calculation of the solubility of quartz is available on: www.geochem-model.org.