中国科学院地球化学研究所Xie Xiande小组近日取得一项新成果。他们报道了SuizhouL6冲击球粒陨石中金属铜的赋存状态及铜的重分布。相关论文于2024年5月21日发表于国际顶尖学术期刊《地球化学学报》杂志上。

据介绍，铜具有很强的亲铁性，但在陨石中发现的条件下，其行为与亲铁元素相似。Suizhou陨石是一颗高激波L6球粒陨石。该陨石中铜的主要载体是陨硫铁和镍纹石，冲击后的热事件被认为是元素铜从原始相迁移并形成金属颗粒的主要原因。Suizhou陨石含有几条极薄的震熔脉。

研究人员通过光学显微镜检查、电子探针分析和高分辨率x射线元素强度图探究了该陨石中金属铜的赋存状态和行为。结果表明，Suizhou球粒陨石中金属铜含量丰富。金属铜晶粒邻近小陨硫铁颗粒在FeNi金属内部最常见，在FeNi金属—陨硫铁界面出现是第二常见的情况。金属铜颗粒出现在FeNi/陨硫铁和硅酸盐的界面上是相当罕见的。

在Suizhou撞击脉中未观察到金属铜颗粒，相反，元素形态的铜通过撞击变质作用转化为FeNi金属+陨硫铁共生。在FeNi金属＋陨硫铁共生体中发现了四种不同的Cu赋存状态：四种赋存状态的FeNi＋FeS共生体中Cu的含量相当接近，研究估计这种可能低于1 wt%。

附：英文原文

Title: The occurrence of metallic copper and redistribution of copper in the shocked Suizhou L6 chondrite

Author: Xie, Xiande, Gu, Xiangping, Yang, Yiping

Issue&Volume: 2024-05-21

Abstract: Copper possesses very strong chacophile properties, but under the conditions found in meteorites, its behavior is like that of siderophile elements. The Suizhou meteorite is a highly shocked L6 chondrite. Troilite and taenite are considered the main primary carrier of copper in this meteorite, and the post-shock thermal episode is considered the main reason that elemental Cu migrates from its original host phase and forms metallic grains. The Suizhou meteorite contains a few very thin shock melt veins. The occurrence and behavior of metallic copper in this meteorite were studied by optical microscopic examination, electron microprobe analyses, and high-resolution X-ray elemental intensity mapping. Our results show that metallic copper is abundant in the Suizhou chondritic rock. Metallic copper grains adjacent to small troilite grains inside FeNi metal are the most common occurrence, and those at the FeNi metal–troilite interface are the second most common case. The metallic copper grains occurring at the interface of FeNi metal/troililte and silicate are rather rare. Metallic copper grains are not observed within the Suizhou shock veins, Instead, Cu in elemental form is transferred through shock metamorphism into FeNi metal+troilite intergrowths. Four different occurrence types of Cu in the FeNi metal+troilite intergrowths have been identified: the concentrations of Cu in the FeNi+FeS intergrowths for four occurrence types are rather close, we estimate it might be lower than 1 wt%.

DOI: 10.1007/s11631-024-00703-4

Source: https://link.springer.com/article/10.1007/s11631-024-00703-4