Connecting the surface expression of impact crater‐related lithologies to planetary or regional subsurface compositions requires an understanding of material transport during crater formation. Here, we use imaging spectroscopy of six clast‐rich impact melt rock outcrops within the well‐preserved 23.5‐Ma, 23‐km diameter Haughton impact structure, Canada, to determine melt rock composition and spatial heterogeneity. We compare results from outcrop to outcrop, using clasts, groundmass, and integrated clast‐groundmass compositions as tracers of transport during crater‐fill melt rock formation and cooling. Supporting laboratory imaging spectroscopy analyses of 91 melt‐bearing breccia and clast samples and microscopic X‐ray fluorescence elemental mapping of cut samples paired with spectroscopy of identical surfaces validate outcrop‐scale lithological determinations. Results show different clast‐rich impact melt rock compositions at three sites kilometers apart and an inverse correlation between silica‐rich (sandstone, gneiss, and phyllosilicate‐rich shales) and gypsum‐rich rocks that suggests differences in source depth with location. In the target stratigraphy, gypsum is primarily sourced from ~1‐km depth, while gneiss is from >1.8‐km depth, sandstone from >1.3 km, and shales from ~1.6–1.7 km. Observed heterogeneities likely result from different excavation depths coupled with rapid quenching of the melt due to high content of cool clasts. Results provide quantitative constraints for numerical models of impact structure formation and give new details on melt rock heterogeneity important in interpreting mission data and planning sample return of impactites, particularly for bodies with impacts into sedimentary and volatile‐bearing targets, e.g., Mars and Ceres.

中文翻译：

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加拿大霍顿冲击构造处冲击熔岩的组成非均质性：对行星过程和遥感的影响

将撞击坑相关岩性的表面表达与行星或区域地下成分组合在一起，需要了解火山口形成过程中的物质传输。在这里，我们使用成像光谱学对加拿大保存完好的23.5 Ma，直径23 km的Haughton碰撞结构内的6个富含裂屑的冲击熔岩露头进行了测定，以确定了熔岩成分和空间非均质性。我们比较了露头与露头的结果，使用碎屑，地面质量和整体碎屑-地面质量组合物作为弹坑填充熔岩形成和冷却过程中的示踪剂。支持对91个熔融角砾岩和碎屑样品进行实验室成像光谱分析，以及对切下的样品进行X射线荧光显微成像，并结合相同表面的光谱，验证了露头规模的岩性测定。结果表明，相距3公里的三个地点的富含胶结的冲击熔岩成分不同，并且富含二氧化硅（砂岩，片麻岩和富含页硅酸盐的页岩）和富含石膏的岩石之间呈反比关系，表明烃源深度随位置而异。在目标地层中，石膏主要来自约1公里的深度，而片麻岩则来自> 1.8公里的深度，砂岩来自> 1.3公里，而页岩则来自约1.6-1.7公里。观察到的异质性可能是由于不同的开挖深度以及由于高含量的碎屑导致的熔体快速淬火所致。