Article,
Hydrocode Simulations of Chicxulub crater collapse and peak-ring formation
Icarus, 157 (1): 24--33 (2002)
Abstract
We use hydrocode modeling to investigate dynamic models for the collapse
of the Chicxulub impact crater. Our aim is to integrate the results
from numerical simulations with kinematic models derived from seismic
reflection and wide-angle velocity data to further our understanding
of the formation of large impact craters. In our simulations, we
model the collapse of a 100-km diameter, bowl-shaped cavity formed
in comprehensively fractured crustal material. To facilitate wholesale
collapse, we require that the strength of the target be significantly
weakened. In the present model, we achieve this using acoustic fluidization,
where strong vibrations produced by the expanding shock wave cause
extreme pressure fluctuations in the target. At times and positions
where the overburden pressure is sufficiently counteracted, the frictional
resistance is reduced, enabling the rock debris to flow. Our simulations
produce a collapsed crater that contains most of the features that
we observe in the seismic data at Chicxulub. In particular, we observe
a topographic peak ring, formed as material that is originally part
of the central uplift collapses outward and is thrust over the inwardly
collapsing transient crater rim. This model for peak-ring generation
has not been previously demonstrated by numerical simulations and
predicts that the peak ring is composed of deeply derived material
and that the stratigraphy within the peak ring is overturned. (C)
2002 Elsevier Science (USA).
