Viscous relaxation of crust of the Sudbury impact structure, Canada

关于地球撞击结构长期变化过程的知识相当稀少，但对于理解不仅是地球上的大陨石撞击过程至关重要。拟议的项目将弥补这一知识差距，对结构进行系统分析，与萨德伯里火成复合体（SIC）的冷却和凝固有关，SIC是加拿大萨德伯里撞击结构的撞击熔融片的遗迹。该项目的目的是阐明这些结构在多大程度上坚持影响引起的，长期地壳松弛静态冷却的SIC和下面的目标岩石。具体而言，矿物织物和花岗岩岩脉的SIC被用来阐明在萨德伯里长期的陨石坑修改的上地壳应变场的演变。矿物组构几何形状的增量变化和绘制的岩脉图案将被比较的应变路径从规模模拟实验解决碰撞陨石坑的粘性地壳松弛。基于现场的结构分析和模拟实验的结果将与原始的表面应变模式进行比较，即，未被侵蚀的撞击结构由于撞击产生的岩性和结构具有极好的暴露、进入和撞击后倾斜，萨德伯里似乎是唯一一个大型的陆地撞击结构，可以进行结构分析，以揭示陆地撞击盆地的长期变化。除了有望为地球上长期的陨石坑改造提供第一个定量结构证据外，这项研究在设计萨德伯里铜镍和铂族元素富集矿床的勘探战略方面也很重要。

Knowledge of long-term modification processes of terrestrial impact structures is rather sparse but paramount for understanding large-meteorite impact processes, not only on Earth. The proposed project will remedy this knowledge gap by conducting a systematic analysis of structures, genetically associated with cooling and solidification of the Sudbury Igneous Complex (SIC), the relic of the impact melt sheet of the Sudbury impact structure, Canada. The objective of the project is to elucidate to what extend these structures adhere to impact-induced, long-term crustal relaxation versus static cooling of the SIC and underlying target rocks. Specifically, mineral fabrics and granitoid dikes of the SIC are used to elucidate the evolution of the upper-crustal strain field during long-term crater modification at Sudbury. The incremental change of mineral fabric geometry and mapped dike patterns will be compared to strain paths obtained from scaled analogue experiments addressing viscous crustal relaxation of impact craters. Results of field-based structural analyses and analogue experiments will be compared to surface strain patterns of pristine, i.e., non-eroded, impact structures on other planets. Owing to the excellent exposure, access and post-impact tilting of impact-generated lithologies and structures, Sudbury appears to be the only large, terrestrial impact structure that allows for a structural analysis aimed at unraveling long-term modification of a terrestrial impact basin. Besides promising to provide the first quantitative structural evidence for long-term crater modification on Earth, the study is also important in terms of designing exploration strategies of Cu-Ni and platinum group element-rich ore deposits at Sudbury.