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SUMMARY:The formation of large impact craters - Gareth Collins\, Imperial 
 College London
DTSTART:20190211T130000Z
DTEND:20190211T140000Z
UID:TALK119293@talks.cam.ac.uk
CONTACT:Prof. Jerome Neufeld
DESCRIPTION:Hypervelocity impacts of large asteroids and comets play a maj
 or role in planetary evolution. For example\, the ~200-km Chicxulub impact
  structure on Earth is widely attributed as the sole or major cause of the
  mass extinction event that wiped out  ~75% of genera\, including non-avia
 n dinosaurs\, at the end of the Cretaceous 66 Ma. Numerical modelling prov
 ides the only means of simulating such large and devastating events\, but 
 such models require testing against geophysical and geological constraints
 . Here I describe recent 2D and 3D numerical simulations of the Chicxulub 
 impact and compare simulation outcomes to geophysical data and the results
  of IODP Expedition 364: a joint drilling expedition in summer 2016 by the
  International Ocean Discovery Program (IODP) and International Continenta
 l Scientific Drilling Program (ICDP). The drill core sampled the Chicxulub
  peak ring\, an enigmatic ring of mountains within the central crater basi
 n\, and shows that the peak ring was formed from uplifted\, fractured\, sh
 ocked\, felsic basement rocks. The peak-ring rocks are cross-cut by dikes 
 and shear zones and have an unusually low density and seismic velocity. Th
 e models and observations support the idea that the Chicxulub peak ring wa
 s formed by the spectacular outward collapse of an overheightened central 
 uplift and provide insight into the impact energy and trajectory\, as well
  as important crustal deformation\, fracturing and pore space creation. 
LOCATION:MR5\, Centre for Mathematical Sciences
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