Choi Jinhyuk, Husband Rachel J, Hwang Huijeong, Kim Taehyun, Bang Yoonah, Yun Seohee, Lee Jeongmin, Sim Heehyeon, Kim Sangsoo, Nam Daewoong, Chae Boknam, Liermann Hanns-Peter, Lee Yongjae
Department of Earth System Sciences, Yonsei University, Seoul 03722, Republic of Korea.
Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, Hamburg 22607, Germany.
Sci Adv. 2023 Dec 15;9(50):eadi6096. doi: 10.1126/sciadv.adi6096.
Giant impact-driven redox processes in the atmosphere and magma ocean played crucial roles in the evolution of Earth. However, because of the absence of rock records from that time, understanding these processes has proven challenging. Here, we present experimental results that simulate the giant impact-driven reactions between iron and volatiles (HO and CO) using x-ray free electron laser (XFEL) as fast heat pump and structural probe. Under XFEL pump, iron is oxidized to wüstite (FeO), while volatiles are reduced to H and CO. Furthermore, iron oxidation proceeds into formation of hydrides (γ-FeH) and siderite (FeCO), implying redox boundary near 300-km depth. Through quantitative analysis on reaction products, we estimate the volatile and FeO budgets in bulk silicate Earth, supporting the Theia hypothesis. Our findings shed light on the fast and short-lived process that led to reduced atmosphere, required for the emergence of prebiotic organic molecules in the early Earth.
大气和岩浆海洋中由巨大撞击驱动的氧化还原过程在地球演化中起着至关重要的作用。然而，由于缺乏那个时期的岩石记录，事实证明理解这些过程具有挑战性。在这里，我们展示了实验结果，该实验使用X射线自由电子激光（XFEL）作为快速热泵和结构探针，模拟了由巨大撞击驱动的铁与挥发性物质（HO和CO）之间的反应。在XFEL泵浦下，铁被氧化成方铁矿（FeO），而挥发性物质被还原成H和CO。此外，铁的氧化过程会形成氢化物（γ-FeH）和菱铁矿（FeCO），这意味着在300公里深度附近存在氧化还原边界。通过对反应产物的定量分析，我们估算了整体硅酸盐地球中的挥发性物质和FeO储量，支持了忒伊亚假说。我们的发现揭示了导致早期地球大气还原的快速且短暂的过程，这是早期地球益生元有机分子出现所必需的。
