Abstract—

The GEOCHEQ_M and GEOCHEQ_Isotope databases and codes were used to simulate the evolution of chemical interactions with time in the closed systems aqueous solution 0.495 М NaCl + 0.0194 M NaHCO₃ + olivine (Fo91) at temperatures of 200 and 320°C and a pressure of 350 bar. The solution to rock mass ratios, selected temperature and pressure, the chemical composition and size of the olivine grains, the chemical composition of the aqueous solution, and the duration of interactions correspond to those in experiments described in (McCollom et al., 2016; McCollom, 2016). The carbon isotope composition of NaHCO₃ was the only one to change. Instead of NaH¹³CO₃ used in the experiment, our simulations were carried out assuming the carbon isotope composition of belemnite from the Peedee Formation, South Carolina, United States. The results of these simulations were compared with the experimental results. As in the experiments, the newly formed mineral assemblage consists of Mg-rich serpentine, brucite, and magnetite, with a minor magnesite amount at 200°С. The calculated rate of olivine serpentinization is close to the experimental one. The calculations yield higher dissolved methane contents than in the experiments. This may be explained by ignoring kinetic constraints of the reaction between dissolved CO₂,aq and hydrogen generated during serpentinization. Fractionation of carbon isotopes was calculated between dissolved inorganic carbon (DIC), newly formed hydrocarbons, and magnesite. The hydrocarbons are significantly enriched in the light isotope with respect to DIC and with respect to magnesite at 200°C.

中文翻译：

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橄榄石蛇纹化的平衡动力学计算。与模型实验的比较

摘要-

GEOCHEQ_M和GEOCHEQ_Isotope数据库和代码用于模拟密闭系统水溶液0.495МNaCl + 0.0194 M NaHCO ₃ +橄榄石（F o91）在200和320°C的温度和200°C的压力下化学相互作用随时间的演变。 350巴 溶液与岩石的质量比，选定的温度和压力，橄榄石颗粒的化学组成和尺寸，水溶液的化学组成以及相互作用的持续时间与（McCollom等，2016; McCollom，2016年）。NaHCO ₃的碳同位素组成是唯一变化的。代替NaH ¹³ CO ₃在实验中，我们假设美国南卡罗来纳州Peedee地层的钙镁铝石的碳同位素组成进行了模拟。将这些模拟的结果与实验结果进行了比较。与实验中一样，新形成的矿物组合由富含Mg的蛇纹石，水镁石和磁铁矿组成，在200°C时有少量菱镁矿。橄榄石蛇纹石化的计算速率接近实验值。计算得出比实验中更高的溶解甲烷含量。可以通过忽略溶解的CO ₂之间反应的动力学约束来解释，蛇形化过程中产生的氢和水。计算了溶解的无机碳（DIC），新形成的碳氢化合物和菱镁矿之间碳同位素的馏分。相对于DIC和相对于菱镁矿，碳氢化合物在200°C时富含轻同位素。