The formation of peak rings in large impact craters
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Large impacts provide a mechanism for resurfacing planets through mixing near-surface rocks with deeper material. Central peaks are formed from the dynamic uplift of rocks during crater formation. As crater size increases, central peaks transition to peak rings. Without samples, debate surrounds the mechanics of peak-ring formation and their depth of origin. Chicxulub is the only known impact structure on Earth with an unequivocal peak ring, but it is buried and only accessible through drilling. Expedition 364 sampled the Chicxulub peak ring, which we found was formed from uplifted, fractured, shocked, felsic basement rocks. The peak-ring rocks are cross-cut by dikes and shear zones and have an unusually low density and seismic velocity. Large impacts therefore generate vertical fluxes and increase porosity in planetary crust.
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Miljkovic, Katarina; Lemelin, M.; Lucey, P. (2017)Numerical modeling of the peak-ring basin formation showed that the peak-ring forms from the material that is part of the central uplift outwardly thrust over the inwardly collapsing transient crater rim. Simulations of ...
Neumann, G.; Zuber, M.; Wieczorek, M.; Head, J.; Baker, D.; Solomon, S.; Smith, D.; Lemoine, F.; Mazarico, E.; Sabaka, T.; Goossens, S.; Melosh, H.; Phillips, R.; Asmar, S.; Konopliv, A.; Williams, J.; Sori, M.; Soderblom, J.; Miljkovic, Katarina; Andrews-Hanna, J.; Nimmo, F.; Kiefer, W. (2015)Observations from the Gravity Recovery and Interior Laboratory (GRAIL) mission indicate a marked change in the gravitational signature of lunar impact structures at the morphological transition, with increasing diameter, ...
Kring, D.; Claeys, P.; Gulick, S.; Morgan, J.; Collins, G.; Bralower, T.; Chenot, E.; Christeson, G.; Cockell, C.; Coolen, Marco; Ferrière, L.; Gebhardt, C.; Goto, K.; Jones, H.; Lofi, J.; Lowery, C.; Mellett, C.; Ocampo-Torres, R.; Perez-Cruz, L.; Pickersgill, A.; Poelchau, M.; Rae, A.; Rasmussen, C.; Rebolledo-Vieyra, M.; Riller, U.; Sato, H.; Smit, J.; Tikoo, S.; Tomioka, N.; Urrutia-Fucugauchi, J.; Whalen, M.; Wittmann, A.; Xiao, L.; Yamaguchi, K.; Zylberman, W. (2017)Copyright 2017, The Geological Society of America. The Chicxulub crater is the only wellpreserved peak-ring crater on Earth and linked, famously, to the K-T or K-Pg mass extinction event. For the first time, geologists ...