美国加州大学Young, Edward D.的研究组认为原始H₂大气塑造了地球。这一研究成果发表在2023年4月12日出版的国际学术期刊《自然》上。

研究团队使用热力学自洽模型表明，地球的水、地核密度和整体氧化态都可以来源于其前身行星胚胎中，富含氢的原始大气和底层岩浆海洋之间的平衡。水是由类似顽辉石球粒陨石的干原料产生的，因为来自岩浆海洋的氧气与氢气反应。来自大气的氢进入岩浆海洋，最终到达处于平衡状态的金属核心导致金属密度不足，与地球相当。

硅酸盐岩石从类似于太阳的氧逸度氧化成类似地球的氧逸度，硅、氢和氧在核心与铁形成合金。因此，与氢气大气和金属硅酸盐平衡的反应为地球化学的基本特征提供了一个简单的解释，这与银河系中岩石行星的形成是一致的。

据了解，地球存在水，内在氧化态和金属核心密度是地球的基本化学特性。对系外行星的研究，为阐明这些化学特征的来源提供了有用的背景。行星形成和演化模型表明，岩石系外行星通常形成富含氢的外壳，这些外壳随着时间的推移而消失。这些发现表明，地球也可能由富含氢的原始大气形成的。

附：英文原文

Title: Earth shaped by primordial H₂ atmospheres

Author: Young, Edward D., Shahar, Anat, Schlichting, Hilke E.

Issue&Volume: 2023-04-12

Abstract: Earth’s water, intrinsic oxidation state and metal core density are fundamental chemical features of our planet. Studies of exoplanets provide a useful context for elucidating the source of these chemical traits. Planet formation and evolution models demonstrate that rocky exoplanets commonly formed with hydrogen-rich envelopes that were lost over time. These findings suggest that Earth may also have formed from bodies with hydrogen-rich primary atmospheres. Here we use a self-consistent thermodynamic model to show that Earth’s water, core density and overall oxidation state can all be sourced to equilibrium between hydrogen-rich primary atmospheres and underlying magma oceans in its progenitor planetary embryos. Water is produced from dry starting materials resembling enstatite chondrites as oxygen from magma oceans reacts with hydrogen. Hydrogen derived from the atmosphere enters the magma ocean and eventually the metal core at equilibrium, causing metal density deficits matching that of Earth. Oxidation of the silicate rocks from solar-like to Earth-like oxygen fugacities also ensues as silicon, along with hydrogen and oxygen, alloys with iron in the cores. Reaction with hydrogen atmospheres and metal–silicate equilibrium thus provides a simple explanation for fundamental features of Earth’s geochemistry that is consistent with rocky planet formation across the Galaxy.

DOI: 10.1038/s41586-023-05823-0

Source: https://www.nature.com/articles/s41586-023-05823-0