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Complex crater formation: Insights from combining observations of shock pressure distribution with numerical models at the West Clearwater Lake impact structure

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Title: Complex crater formation: Insights from combining observations of shock pressure distribution with numerical models at the West Clearwater Lake impact structure
Authors: Rae, A
Collins, GS
Grieve, RAF
Osinki, GR
Morgan, JV
Item Type: Journal Article
Abstract: Large impact structures have complex morphologies, with zones of structural uplift that can be expressed topographically as central peaks and/or peak rings internal to the crater rim. The formation of these structures requires transient strength reduction in the target material and one of the proposed mechanisms to explain this behavior is acoustic fluidization. Here, samples of shock-metamorphosed quartz-bearing lithologies at the West Clearwater Lake impact structure, Canada, are used to estimate the maximum recorded shock pressures in three dimensions across the crater. These measurements demonstrate that the currently-observed distribution of shock metamorphism is strongly controlled by the formation of the structural uplift. The distribution of peak shock pressures, together with apparent crater morphology and geological observations, is compared with numerical impact simulations to constrain parameters used in the block-model implementation of acoustic fluidization. The numerical simulations produce craters that are consistent with morphological and geological observations. The results show that the regeneration of acoustic energy must be an important feature of acoustic fluidization in crater collapse, and should be included in future implementations. Based on the comparison between observational data and impact simulations we conclude that the West Clearwater Lake structure had an original rim (final crater) diameter of 35–40 km and has since experienced up to ~2 km of differential erosion.
Issue Date: 6-Feb-2017
Date of Acceptance: 11-Dec-2016
URI: http://hdl.handle.net/10044/1/43147
DOI: https://dx.doi.org/10.1111/maps.12825
ISSN: 1086-9379
Publisher: Wiley
Start Page: 1330
End Page: 1350
Journal / Book Title: Meteoritics & Planetary Science
Volume: 52
Issue: 7
Copyright Statement: © 2017 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals, Inc. on behalf of The Meteoritical Society 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.
Sponsor/Funder: The Leverhulme Trust
Science and Technology Facilities Council (STFC)
Funder's Grant Number: F07058AQ
Keywords: Geochemistry & Geophysics
0201 Astronomical And Space Sciences
0402 Geochemistry
0403 Geology
Publication Status: Published
Appears in Collections:Earth Science and Engineering
Faculty of Engineering