This study reconstructs the pre-impact orientation of impact-generated µm-sized microstructures. The approach is illustrated using a sample from the basement dolerites of the Lockne impact structure, Sweden. Under the polarised light microscope, the microstructure appears as alternating augite-plagioclase wedges. The top-view of the microstructure is presented in the polished thin-section using light and scanning electron microscopy, while, the side-view is observed in focused-ionbeam trenches in a field emission scanning electron microscope. The top- and side view of the wedges are projected on a stereo net, which allows the determination of their 3D orientation. The wedges are thus found to have a dip of 08° towards 280°. The stereo net projections are then used to reconstruct the orientation of pre-impact boundary between augite-plagioclase, which had a dip of 15° towards 237°. This approach of combining light and electron microscopy with FIB trenching and projecting the data on a stereo net can be especially useful for reconstructing the pre-deformed state of impact-induced or tectonic µm-sized microstructures, which cannot be adequately analysed using a light microscope.

中文翻译：

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使用光学和电子显微镜对冲击微结构进行立体重建

本研究重建了冲击产生的微米级微结构的冲击前取向。使用瑞典洛克恩撞击结构的基底玄武岩样品说明了该方法。在偏光显微镜下，微观结构表现为交替的辉石-斜长石楔形。使用光学和扫描电子显微镜在抛光薄片中呈现微观结构的顶视图，而在场发射扫描电子显微镜中在聚焦离子束沟槽中观察侧视图。楔子的顶视图和侧视图被投影到立体网络上，从而可以确定它们的 3D 方向。因此发现楔形物具有朝向 280° 的 08° 倾角。然后使用立体网络投影来重建辉石-斜长石之间碰撞前边界的方向，向 237° 倾斜了 15°。这种将光学和电子显微镜与 FIB 挖沟相结合并将数据投影到立体网络上的方法对于重建冲击诱导或构造微米级微结构的预变形状态特别有用，这些微结构无法使用光学显微镜进行充分分析.