SOLUBILITY OF ROCK IN STEAM ATMOSPHERES OF PLANETS
SOLUBILITY OF ROCK IN STEAM ATMOSPHERES OF PLANETS
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DOI：
10.3847/0004-637x/824/2/103
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发表时间：
2016-02
期刊：
影响因子：
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通讯作者：
B. Fegley;N. Jacobson;K. B. Williams;J. Plane;L. Schaefer;K. Lodders
中科院分区：
文献类型：
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作者：
B. Fegley;N. Jacobson;K. B. Williams;J. Plane;L. Schaefer;K. Lodders
大量的实验研究表明，所有主要的造岩元素（如Si、Mg、Fe、Ca、Al、Na、K）都或多或少地溶解于蒸汽中。我们利用这些结果计算了含岩石元素气体在与硅酸盐岩浆海洋平衡的蒸汽大气中的化学平衡丰度。岩石元素作为挥发性氢氧化物气体(如Si(OH)4、Mg(OH)2、Fe(OH)2、Ni(OH)2、Al（OH)3、Ca(OH)2、NaOH、KOH）进入蒸汽大气，并通过与HF和HCl反应成为挥发性卤化物气体（如NaCl、KCl、CaFOH、CaClOH、FAl(OH)2），其数量远远超过了在早期地球和热岩石系外行星蒸汽大气中高温下在无挥发固体或熔融岩石上的蒸气压所预期的数量。我们通过定义气体/岩浆分布系数定量计算了部分汽化程度，并表明地球的亚太阳Si/Mg比值可能是由于原始蒸汽大气的损失。我们得出的结论是，正在或已经经历蒸汽气氛逃逸的热岩系外行星可能会经历部分汽化和Si， Mg, Fe, Ni, Al, Ca， Na和k的损失，这种损失可以改变它们的体积组成，密度，热平衡和内部结构。
Extensive experimental studies show that all major rock-forming elements (e.g., Si, Mg, Fe, Ca, Al, Na, K) dissolve in steam to a greater or lesser extent. We use these results to compute chemical equilibrium abundances of rocky-element-bearing gases in steam atmospheres equilibrated with silicate magma oceans. Rocky elements partition into steam atmospheres as volatile hydroxide gases (e.g., Si(OH)4, Mg(OH)2, Fe(OH)2, Ni(OH)2, Al(OH)3, Ca(OH)2, NaOH, KOH) and via reaction with HF and HCl as volatile halide gases (e.g., NaCl, KCl, CaFOH, CaClOH, FAl(OH)2) in much larger amounts than expected from their vapor pressures over volatile-free solid or molten rock at high temperatures expected for steam atmospheres on the early Earth and hot rocky exoplanets. We quantitatively compute the extent of fractional vaporization by defining gas/magma distribution coefficients and show that Earth's subsolar Si/Mg ratio may be due to loss of a primordial steam atmosphere. We conclude that hot rocky exoplanets that are undergoing or have undergone escape of steam-bearing atmospheres may experience fractional vaporization and loss of Si, Mg, Fe, Ni, Al, Ca, Na, and K. This loss can modify their bulk composition, density, heat balance, and interior structure.