Viscous relaxation of crust of the Sudbury impact structure, Canada

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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.