Impact‐Induced Porosity and Microfracturing at the Chicxulub Impact Structure
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2019-07-26
Submitted Date
2019-01-21
Subject Terms
cratering
porosity
Chicxulub
fractures
porosity
Chicxulub
fractures
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Abstract
Abstract: Porosity and its distribution in impact craters has an important effect on the petrophysical properties of impactites: seismic wave speeds and reflectivity, rock permeability, strength, and density. These properties are important for the identification of potential craters and the understanding of the process and consequences of cratering. The Chicxulub impact structure, recently drilled by the joint International Ocean Discovery Program and International Continental scientific Drilling Program Expedition 364, provides a unique opportunity to compare direct observations of impactites with geophysical observations and models. Here, we combine small‐scale petrographic and petrophysical measurements with larger‐scale geophysical measurements and numerical simulations of the Chicxulub impact structure. Our aim is to assess the cause of unusually high porosities within the Chicxulub peak ring and the capability of numerical impact simulations to predict the gravity signature and the distribution and texture of porosity within craters. We show that high porosities within the Chicxulub peak ring are primarily caused by shock‐induced microfracturing. These fractures have preferred orientations, which can be predicted by considering the orientations of principal stresses during shock, and subsequent deformation during peak ring formation. Our results demonstrate that numerical impact simulations, implementing the Dynamic Collapse Model of peak ring formation, can accurately predict the distribution and orientation of impact‐induced microfractures in large craters, which plays an important role in the geophysical signature of impact structures.
Citation
Rae, A. S. P., Collins, G. S., Morgan, J. V., Salge, T., Christeson, G. L., Leung, J., et al. (2019). Impact-induced porosity and microfracturing at the Chicxulub impact structure. Journal of Geophysical Research: Planets, 124, 1960–1978. https://doi.org/10.1029/2019JE005929
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Copyright ©2019. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. The linked article is the published version of the article.
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ISSN
2169-9097
EISSN
2169-9100