Fabric analysis of Allende matrix using EBSD
Fabric analysis of Allende matrix using EBSD
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DOI：
10.1111/j.1945-5100.2006.tb00499.x
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发表时间：
2006-07
影响因子：
2.2
通讯作者：
L. E. Watt;P. Bland;D. Prior;S. Russell
中科院分区：
文献类型：
--
作者：
L. E. Watt;P. Bland;D. Prior;S. Russell
摘要：原始陨石中的间隙基质材料的结构分析为小行星的形成和演化提供了一个新的窗口。电子背散射衍射（EBSD）首次使这些细颗粒材料中的结构得以详细可视化。我们的数据显示，阿连德，一个CV 3球粒陨石，具有一个均匀的，平面的，短轴排列组构，这是普遍存在于广泛的规模，可能是变形缩短有关的影响或重力压实的结果。这种基质组构与更大、更刚性的组分（如深色夹杂物（DI）和富钙铝夹杂物（CAIs））之间的干扰导致了局部取向和强化基质组构的发展。此外，DI具有与更宽的基质织物相适应的织物。这些结果表明，DI是在变形缩短事件之前，负责这些织物的原位，从而提供了一个论点，反对黑暗的夹杂物是来自小行星的另一个石化部分的碎片（Kojima和Tomeoka 1996年; Fruland等人1978年）。此外，DI和阿连德基质均具有高度多孔性（<25%）（科里根等人，1997）。在冲击诱导角砾岩化过程中，不施加织物，并将其纳入高度多孔的基质中，而不显著压实这些材料，是不可能的。我们倾向于一个模型，涉及阿连德DI，CAI和矩阵吸积在一起，并经历相同的变形事件。
Abstract— Fabric analysis of the interstitial matrix material in primitive meteorites offers a novel window on asteroid formation and evolution. Electron backscatter diffraction (EBSD) has allowed fabrics in these fine‐grained materials to be visualized in detail for the first time. Our data reveal that Allende, a CV3 chondrite, possesses a uniform, planar, short‐axis alignment fabric that is pervasive on a broad scale and is probably the result of deformational shortening related to impact or gravitational compaction. Interference between this matrix fabric and the larger, more rigid components, such as dark inclusions (DIs) and calcium‐aluminium‐rich inclusions (CAIs), has lead to the development of locally oriented and intensified matrix fabrics. In addition, DIs possess fabrics that are conformable with the broader matrix fabric. These results suggest that DIs were in situ prior to the deformational shortening event responsible for these fabrics, thus providing an argument against dark inclusions being fragments from another lithified part of the asteroid (Kojima and Tomeoka 1996; Fruland et al. 1978). Moreover, both DIs and Allende matrix are highly porous (˜25%) (Corrigan et al. 1997). Mobilizing a highly porous DI during impact‐induced brecciation without imposing a fabric and incorporating it into a highly porous matrix without significantly compacting these materials is improbable. We favor a model that involves Allende DIs, CAIs, and matrix accreting together and experiencing the same deformation events.