Proposed structures for poorly characterized phases in C2M carbonaceous chondrite meteorites
Proposed structures for poorly characterized phases in C2M carbonaceous chondrite meteorites
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C2M 碳质球粒陨石中特征较差的相的拟议结构
作者：
I. Mackinnon;M. Zolensky
最近使用分析电子显微镜和高分辨率透射电子显微镜（HRTEM）对陨石基质进行的研究提供了关于特征不明显相（PCP）的结构和化学的数据1。我们在此提出，作为主要基质品种的~ 10 Å PCP，其结构相当于富铁的tochilinite [6Fe0.9S 5(Fe, Mg) (OH)2]，由连贯的间层状镁铁石和水闪石片组成。此外，我们提出，先前被描述为sbb型混合层结构的~ 17 Å PCP是蛇纹岩和毒力石层的相称共生。在毒力石和蛇纹石-毒力石结构类型中都可能存在广泛的阳离子取代。我们认为，在碳质球粒陨石中观察到的各种形式的PCP是蛇纹石、蛇纹石、蛇纹石-蛇纹石和/或变晶石型矿物的共生产物。
Recent investigations of meteorite matrices using analytical electron microscopy and high-resolution transmission electron microscopy (HRTEM) have provided data on the structure and chemistry of poorly characterized phases (PCP)1. We suggest here that ∼10 Å PCP, a dominant matrix variety, has a structure equivalent to iron-rich tochilinite [6Fe0.9S 5(Fe, Mg) (OH)2] which consists of coherently interstratified mackinawite and brucite sheets2. In addition, we propose that ∼17 Å PCP, previously described as an SBB-type mixed-layer structure3, is a commensurate intergrowth of serpentine and tochilinite layers. A wide range of cation substitutions is possible within both tochilinite and serpentine–tochilinite structural types. We suggest that various forms of PCP observed in carbonaceous chondrites4,5are intergrowths of tochilinite, serpentine, serpentine–tochilinite and/or valleriite-type minerals6.