中国科学院地球化学研究所朱丹和杜蔚利用来自嫦娥五号玻璃珠的启示，研究了撞击引起的氧化还原条件变化。这一研究成果发表在2024年3月4日出版的国际学术期刊《科学通报》上。

在这项研究中，研究人员根据对嫦娥五号任务中撞击玻璃珠的研究，对撞击事件引起的月壤风化层氧化还原状态的变化提出了一种可能的解。这些玻璃微珠含有铁金属颗粒，从边缘到中心呈现FeO和K₂O(含或不含Na₂O)的浓度梯度。成分分布图显示出类似于误差函数的形状，这表明扩散机制限制机制。数值模拟结果表明，玻璃珠表面的铁金属颗粒是由撞击事件中产生的元素K和(或)Na还原FeO而产生的。

同时，在氧化还原电位梯度的驱动下，铁金属颗粒可能是由于氧扩散而形成的。此外，研究结果表明，撞击过程会强化局部还原条件，与玻璃珠表面的铁金属颗粒共存的硫铁矿颗粒中存在硫化钙颗粒就是最好的证明。这项研究为铁金属球粒形成过程中氧扩散动力学提供了见解，并揭示了撞击事件引发的月球物质氧化还原条件的变化。

据悉，与地球上的物质相比，月球上的物质总体上更具有还原性，但其机制仍有待阐明。

附：原文原文

Title: Redox condition changes caused by impacts: Insights from Chang’e-5 lunar glass beads

Author: anonymous

Issue&Volume: 2024/03/04

Abstract: Lunar materials are overall more reducing compared to their terrestrial counterparts, but the mechanism remains to be elucidated. In this study, we present a possible explanation for the changes in redox state of the lunar regolith caused by impact events, based on our investigations of impact glass beads from the Chang’e-5 mission. These glass beads contain iron metal grains and show concentration gradients of FeO and K₂O (with or without Na₂O) from their rims to centers. The compositional profiles exhibit error-function-like shapes, which indicates a diffusion-limited mechanism. Our numerical modeling results suggest that the iron metal grains on the surface of the glass beads were generated through the reduction of FeO by elemental K and (or) Na produced during the impact event. Meanwhile, the iron metal grains inside the bead may have formed due to oxygen diffusion driven by redox potential gradients. Furthermore, our study suggests that impact processes intensify the local reducing conditions, as evidenced by the presence of calcium sulfide particles within troilite grains that coexist with iron metal grains on the surface of the glass beads. This study provides insights into the oxygen diffusion kinetics during the formation of iron metal spherules and sheds light on the changes in redox conditions of lunar materials caused by impact events.

DOI: 10.1016/j.scib.2024.03.004

Source: https://www.sciencedirect.com/science/article/abs/pii/S2095927324001488