Asymmetric shock deformation at the Spider impact structure, Western Australia
Asymmetric shock deformation at the Spider impact structure, Western Australia
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西澳大利亚州蜘蛛撞击结构的不对称冲击变形
DOI：
10.1111/maps.13621
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发表时间：
2021
影响因子：
2.2
通讯作者：
P. Bland
中科院分区：
文献类型：
--
作者：
M. A. Cox;A. Cavosie;M. Poelchau;T. Kenkmann;K. Miljković;P. Bland
冲击变形效应的分布以及冲击结构的结构表达可以是不对称的，这取决于目标岩石岩性（例如，层状与均质）、目标岩石的孔隙度和撞击角度。在这里，我们提出了一个详细的研究冲击变形石英和锆石在硅化砂岩从不对称蜘蛛影响结构在澳大利亚。我们利用光学显微镜和电子背散射衍射（EBSD）技术，以确定冲击变形锆石的空间分布，沿着一个downrange横断面横跨中央隆起的结构，与约束的物理分布的冲击效应产生的斜冲击的目标。利用电子背散射衍射技术对该构造内12个含破碎锥的石英岩和角砾岩样品中的453个锆石颗粒进行了原位薄片冲击变形测量。19个锆石颗粒含有{112}孪晶，其中包括一个具有三个孪晶取向的颗粒。从五个样品的石英颗粒沿着横断面也进行了调查，以确定方向的平面变形功能，平面裂缝，羽毛功能，并提供一个基线的数据比较锆石。与石英相反，在所调查的样品中具有{112}孪晶的冲击锆石的分布相对于结构中心似乎是不对称的，从而提供了第一个基于辅助矿物的证据，支持冲击变形作为冲击韧性的函数的不对称分布。我们的研究结果是一个例子，观察到的冲击变形的最高强度不对应的地理中心的结构，并可以作为指导实地研究，旨在记录在其他网站的冲击效应的分布解释，导致斜的影响。
The distribution of shock deformation effects, as well as the structural expression of an impact structure, can be asymmetric, depending on target rock lithologies (e.g., layered versus homogenous), porosity of target rock, and angle of impact. Here, we present a detailed study of shock‐deformed quartz and zircon in silicified sandstones from the asymmetric Spider impact structure in Australia. We utilize optical microscopy and electron backscatter diffraction (EBSD) techniques in order to determine the spatial distribution of shock‐deformed zircon along a downrange transect across the central uplift of the structure, with the goal of constraining the physical distribution of shock effects created by an oblique impact. A total of 453 zircon grains from 12 samples of shatter cone‐bearing quartzite and breccia within the structure were surveyed for shock deformation by EBSD in situ within thin sections. Nineteen zircon grains contain {112} twins, including one grain with three twin orientations. Quartz grains from five samples along the transect were also surveyed using a universal stage in order to determine orientations of planar deformation features, planar fractures, and feather features, and to provide a baseline for comparison of data from zircon. The distribution of shocked zircon with {112} twins within the samples surveyed appears to be asymmetric relative to the center of the structure, in contrast to quartz, thus providing the first accessory mineral‐based evidence that supports an asymmetric distribution of shock deformation as a function of impact obliquity. Our results are an example where the highest intensity of observed shock deformation does not correspond to the geographic center of the structure, and may serve as a guide for field studies aimed at documenting the distribution of shock effects at other sites interpreted to result from oblique impacts.
MEMIN 冲击实验中破碎锥的形成
影响因子：
2.2
作者：
Wilk J.;Kenkmann T.
通讯作者：
Kenkmann T.
影响因子：
2.2
作者：
M. A. Cox;T. Erickson;M. Schmieder;R. Christoffersen;D. Ross;A. Cavosie;P. Bland;D. Kring
通讯作者：
M. A. Cox;T. Erickson;M. Schmieder;R. Christoffersen;D. Ross;A. Cavosie;P. Bland;D. Kring
影响因子：
3.2
作者：
Elbeshausen, Dirk;Wuennemann, Kai;Collins, Gareth S.
通讯作者：
Collins, Gareth S.