Winchcombe: An example of rapid terrestrial alteration of a CM chondrite
Winchcombe: An example of rapid terrestrial alteration of a CM chondrite
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Winchcombe：CM 球粒陨石快速陆地蚀变的一个例子
DOI：
10.1111/maps.13949
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发表时间：
2023
影响因子：
2.2
通讯作者：
Jenkins L
中科院分区：
文献类型：
--
作者：
Jenkins L
温奇科姆是一块CM球粒陨石，于2021年2月28日在英国坠落。它的快速检索具有很好的特点。在温奇科姆的两个抛光切片中，观察到了陆地相。在2021年3月6日从野外回收的样品中发现了方解石和硫酸钙，2021年3月2日从车道上回收的样品几个月后在样品上观察到了岩盐。用扫描电子显微镜、拉曼光谱和透射电子显微镜对这些陆相进行了表征。方解石矿脉横切熔融地壳，因此其形成时间较晚。方解石可能是在潮湿的环境(羊场)中沉淀下来的，陨石在那里放置了6 天，然后才被取回。硫酸盐赋存于样品的边缘，经鉴定为三种矿物：石膏、镁铝榴石和硬石膏。考虑到硫酸盐只存在于样品的边缘，包括熔融地壳的顶部，它们是在温奇科姆坠落后形成的。硫酸盐沉淀归因于潮湿的坠落环境，可能是由于硫化物产生的硫化氢与陨石中的方解石反应所致。盐岩只在抛光部分的表面上以自面体晶体的形式出现，并且只出现在相对富含钠的区域。它很可能是抛光的石片与实验室潮湿的空气经过几个月的相互作用而产生的。硫酸盐、熔融结壳方解石和盐岩都是温奇科姆进入地球大气层的日期，并展示了陨石坠落的速度可以被陆地改变。
Winchcombe is a CM chondrite that fell in England on February 28, 2021. Its rapid retrieval was well characterized. Within two polished sections of Winchcombe, terrestrial phases were observed. Calcite and calcium sulfates were found in a sample recovered from a field on March 6, 2021, and halite was observed on a sample months after its recovery from a driveway on March 2, 2021. These terrestrial phases were characterized by scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. Calcite veins crosscut the fusion crust and therefore postdate it. The calcite likely precipitated in the damp environment (sheep field) where the meteorite lay for six days prior to its retrieval. The sulfates occur on the edges of the sample and were identified as three minerals: gypsum, bassanite, and anhydrite. Given that the sulfates occur only on the sample's edges, including on top of the fusion crust, they formed after Winchcombe fell. Sulfate precipitation is attributed to the damp fall environment, likely resulted from sulfide‐derived H2S reacting with calcite within the meteorite. Halite occurs as euhedral crystals only on the surface of a polished section and exclusively in areas relatively enriched in sodium. It was likely produced by the interaction of the polished rock slice with the humid laboratory air over a period of months. The sulfates, fusion crust calcite, and halite all post‐date Winchcombe's entry into the Earth's atmosphere and showcase how rapidly meteorite falls can be terrestrially altered.