Three-dimensional petrography of metal phases in equilibrated L chondrites—Effects of shock loading and dynamic compaction
Three-dimensional petrography of metal phases in equilibrated L chondrites—Effects of shock loading and dynamic compaction
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平衡 L 球粒陨石中金属相的三维岩相学——冲击载荷和动力压实的影响
DOI：
10.1016/j.epsl.2008.08.024
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发表时间：
2008
影响因子：
5.3
通讯作者：
D. Ebel
中科院分区：
文献类型：
--
作者：
J. Friedrich;D. P. Wignarajah;S. Chaudhary;M. Rivers;C. Nehru;D. Ebel
为了研究碰撞在小行星演化中的作用，通过其球粒陨石后代，我们用同步X射线显微断层扫描技术对一组日益受到冲击的L球粒陨石中的金属颗粒进行了定量的三维(3D)研究。我们的数据可以对球粒陨石中Fe(Ni)金属相的尺寸-数量分布和集体形态进行严格的量化。在我们XMT测量的分辨率(8.4-17.9μm/体素)下，金属颗粒的数量随着岩相学识别的冲击载荷程度的增加而增加，这表明Fe-Ni金属在这个尺度或更低的尺度上聚集在一起。结果表明，冲击压实和冲击加载程度越大，金属颗粒择优取向的集合度越高。L球粒陨石中的延性金属颗粒在峰值冲击压力<；5 Gpa时开始表现出片理，这种压力足以致密和硬化松散结合的球粒陨石物质，我们的结果为作用于L母体的多代撞击事件提供了证据。
To examine the role of impacts in the evolution of asteroids as seen through their chondritic offspring, we have performed a quantitative three dimensional (3D) study of metal grains in a suite of increasingly shocked L chondrites with synchrotron X-ray microtomography (XMT). Our data allow rigorous quantification of size-number distributions and collective morphology of Fe(Ni) metal phases in chondritic meteorites. At the resolution of our XMT measurements (8.4–17.9 μm/voxel), the number of metal particles increase with higher degrees of petrographically identified shock loading, indicating a coalescing of Fe–Ni metal at or below this scale. Our results demonstrate that collective degrees of metal grain preferred orientation increase with greater degrees of impact-related compaction and shock loading. Ductile metal grains in L chondrites begin to show foliation at peak shock pressures <5 GPa, pressures great enough to compact and indurate loosely bound chondritic material, and our results constitute evidence for multiple generations of impact events acting on the L parent body or bodies.