Numerical Modeling of the Largest Terrestrial Meteorite Craters

Abstract

Multi-ring impact basins have been found on the surfaces of almost all planetary bodies in the Solar system with solid crusts. The details of their formation mechanism are still unclear. We present results of our numerical modeling of the formation of the largest known terrestrial impact craters. The geological and geophysical data on these structures accumulated over many decades are used to place constraints on the parameters of available numerical models with a dual purpose: (i) to choose parameters in available mechanical models for the crustal response of planetary bodies to a large impact and (ii) to use numerical modeling to refine the possible range of original diameters and the morphology of partially eroded terrestrial craters. We present numerical modeling results for the Vredefort, Sudbury, Chicxulub, and Popigai impact craters and compare these results with available geological and geophysical information.

The formation of peak rings in large impact craters

“…Fig. 1) are consistent with the dynamic collapse model in that they reproduce this mode of peak-ring formation as well as other crater features such as the observed mantle uplift and terrace zone (16)(17)(18)(19)(20). For the simulation in Figure 1 we used well and geophysical data to construct the pre-impact target, which is comprised of a 33-km thick crust with ~3-km of sedimentary rocks above basement (21).…”

Chicxulub and the Exploration of Large Peak-Ring Impact Craters through Scientific Drilling

“…5) favors a dynamic collapse model for an over-heightened central uplift (Morgan et al, 2016), which is consistent with observations at other terrestrial craters (Grieve et al, 1981) and with an earlier set of numerical models of the Chicxulubforming event (Collins et al, 2002;Ivanov, 2005;Collins et al, 2008). It is also similar to the processes inferred from geologic mapping and numerical modeling of the Schrödinger peak-ring on the Moon .…”

Volume 364: Chicxulub: Drilling the K-Pg Impact Crater

“…The recovered core will be used to test the working hypotheses that peak rings are formed from (1) overturned and uplifted basement rocks, (2) megabreccias, or (3) some other material. If the peak ring is formed from uplifted rocks, as predicted by several independent numerical simulations of crater formation ( Figure F5) (Collins et al, 2002;Ivanov, 2005;Senft and Stewart, 2009), then we can estimate their depth of origin (upper crust or deeper) using metamorphic grade, thermochronology, and possibly remanent magnetism. The orientation of impact-induced discontinuities, which may include breccia zones, brittle shear faults, and melt-filled fractures, will be used to infer the strain geometry (i.e., the orientation) and potentially also the magnitude of the three principal strain axes during peak-ring formation and thus constrain the kinematics of peak-ring Figure F6 (continued).…”

“…Modified from ; from Nature Geoscience. formed during the collapse of a deep bowl-shaped "transient cavity" formed during the initial stages of cratering ( Figure F5) (Morgan et al, 2000;Collins et al, 2002;Ivanov, 2005;Senft and Stewart, 2009). During this collapse, structural uplift of the crater floor produces a central uplift, which is overheightened and unstable under gravity.…”