Viscous relaxation of crust of the Sudbury impact structure, Canada
Final Report Abstract
Based chiefly on structural field evidence from the Sudbury impact structure, Canada, the mechanism of long-term crustal relaxation was addressed by examining mineral fabrics, slip on post-cratering faults, impact melt rock dikes and sulphide veins in target rocks underlying the Sudbury Igneous Complex, Canada. Collectively, the results point to formation of these structures on time scales of tens of thousands of years and kinematically associated with longterm crater modification consistent with relaxation of crust below the impact structure. Significant progress was also achieved in terms of better understanding the chemical evolution and emplacement of Cu-Ni-PGE-rich sulphides in crater floor fractures, known as Offset Dikes at Sudbury. Complemented by a geochemical and geophysical analysis of equivalent impact melt rock dikes of the Vredefort impact structure, South Africa, crustal relaxation occurred kinematically as a direct consequence of dynamic collapse of a transient cavity, however at significantly lower strain rates than occurring during cratering. The results of the project challenge a long-standing paradigm in impact tectonics, in which deformation of target rock is exclusively caused by impact and cratering, both operating on time scales of seconds and minutes, respectively.
Publications
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2018. 3-D kinematic restoration of the eastern Sudbury Igneous Complex, Canada, and its importance for Cu-Ni-PGE sulphide exploration. Ore Geology Review 101, 199-210
Clark, Martin D. & Riller, Ulrich
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2019. Genetic relationship between post-cratering dynamics and footwall deposit formation at Sudbury, Ontario, Canada: importance for sulfide ore exploration. Economic Geology 114, 599-611
Wüstemann, Torben; Göllner, Paul; Lightfoot, Peter C. & Riller, Ulrich
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2019. Thermo-mechanical interaction of a large impact melt sheet with adjacent target rock, Sudbury impact structure, Canada. Meteoritics and Planetary Science 54, 1228-1245
Göllner, Paul L.; Wüstemann, Torben; Bendschneider, Lisa; Reimers, Sebastian; Clark, Martin D.; Gibson, Lisa; Lightfoot, Peter C. & Riller, Ulrich
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2020. Modeling the geochemical evolution of impact melts in terrestrial impact basins: Vredefort Granophyre Dikes and Sudbury Offset Dikes. Meteoritics & Planetary Science 55, 2320-2337
Huber, Matthew S.; Kovaleva, Elizaveta & Riller, Ulrich
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2021. Data on the geology and structure of the Copper Cliff embayment and offset dyke, Sudbury Igneous Complex, Canada. Data in Brief 35, 106957
Mathieu, Lucie; Riller, Ulrich; Gibson, Lisa & Lightfoot, Peter
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2021. Structural controls on the localization of the mineralized Copper Cliff embayment and the Copper Cliff offset dyke, Sudbury Igneous Complex, Canada. Ore Geology Reviews 133, 104071
Mathieu, Lucie; Riller, Ulrich; Gibson, Lisa & Lightfoot, Peter
