近日，中国科学院地质与地球物理研究所林杨挺教授及其课题组的最新研究，对嫦娥五号月壤中保存的铁陨石碎片进行了首次分类。这一研究成果发表在2023年12月19日出版的国际学术期刊《科学通报》上。

该课题组首次报道了嫦娥五号月球土壤中发现的铁陨石碎片，该碎片主要由马氏体(由镍纹石淬火而成)、铁纹石和陨铁镍石组成，并含有少量镍黄铁矿。陨石碎片富含镍和磷，贫硫，根据其矿物化学和成分组成，可归类为IID族，这是一种罕见的起源于外太阳系的碳质铁陨石。

这些陨石碎片只经历了有限的部分熔融，随后迅速冷却，研究表明铁陨石的完整残余物在撞击多孔的月球风化层时得到了有效的保存。另一种说法是，它是由一颗类似IID族的铁陨石产生的亚毫米级别的金属颗粒低速撞击的遗迹。研究观测表明，通过系统分析从月球土壤中分离出的大量金属颗粒，来获得撞击月球的陨石类型分布是可行的，这为揭示太阳系的动态演化提供了线索。

据介绍，月球土壤保存了大量撞击月球的陨石碎片，为研究数十亿年来各种类型抛射物的分布提供了一个独特的机会。

附：英文原文

Title: First classification of iron meteorite fragment preserved in Chang’e-5 lunar soils

Author: Xiaoying Liu, Lixin Gu, Heng-Ci Tian, Jing Li, Xu Tang, Sen Hu, Yangting Lin

Issue&Volume: 2023/12/19

Abstract: Lunar soil preserves numerous fragments of meteorites impacting on the Moon, providing a unique opportunity to investigate the distribution of the types of projectiles over billions of years. Here we report the first discovery of an iron meteorite fragment from the Chang’e-5 lunar soil, which consists mainly of martensite (quenched from taenite), kamacite, and schreibersite, with a trace of pentlandite. The meteorite fragment is Ni- and P-rich, S-poor, and based on its mineral chemistry and bulk composition, can be classified into the IID-group, a rare and carbonaceous group of iron meteorite originating in the outer Solar System. This meteorite fragment experienced only limited partial melting followed by fast cooling, suggestive of efficient preservation of intact remnants of iron meteorites impacting on the porous lunar regolith. Alternatively, it is a relic of a low-velocity impact of submillimeter-sized metal grains originated from an IID-like iron meteorite. Our observations demonstrate that it is feasible to achieve the type distribution of meteorites impacting on the Moon via systematically analyzing a large number of metal grains separated from lunar soils, thus shedding light on the dynamic evolution of the Solar System.

DOI: 10.1016/j.scib.2023.12.032

Source: https://www.sciencedirect.com/science/article/abs/pii/S2095927323008939