Microstructural dynamics of central uplifts: Reidite offset by zircon twins at the Woodleigh impact structure, Australia

Impact cratering is a dynamic process that is violent and fast. Quantifying processes that accommodate deformation at different scales during central uplift formation in complex impact structures is therefore a challenging task. The ability to correlate mineral deformation at the microscale with mac...

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Main Authors: Cox, Morgan, Cavosie, Aaron, Bland, Phil, Mijkovic, Katarina, Wingate, M.
Format: Journal Article
Published: Geological Society of America 2018
Online Access:http://hdl.handle.net/20.500.11937/72738
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author Cox, Morgan
Cavosie, Aaron
Bland, Phil
Mijkovic, Katarina
Wingate, M.
author_facet Cox, Morgan
Cavosie, Aaron
Bland, Phil
Mijkovic, Katarina
Wingate, M.
author_sort Cox, Morgan
building Curtin Institutional Repository
collection Online Access
description Impact cratering is a dynamic process that is violent and fast. Quantifying processes that accommodate deformation at different scales during central uplift formation in complex impact structures is therefore a challenging task. The ability to correlate mineral deformation at the microscale with macroscale processes provides a critical link in helping to constrain extreme crustal behavior during meteorite impact. Here we describe the first high-pressure-phase–calibrated chronology of shock progression in zircon from a central uplift. We report both shock twins and reidite, the high-pressure ZrSiO4 polymorph, in zircon from shocked granitic gneiss drilled from the center of the >60-km-diameter Woodleigh impact structure in Western Australia. The key observation is that in zircon grains that contain reidite, which forms at >30 GPa during the crater compression stage, the reidite domains are systematically offset by later-formed shock deformation twins (∼20 GPa) along extensional planar microstructures. The {112} twins are interpreted to record crustal extension and uplift caused by the rarefaction wave during crater excavation. These results provide the first physical evidence that relates the formation sequence of both a high-pressure phase and a diagnostic shock microstructure in zircon to different cratering stages with unique stress regimes that are predicted by theoretical and numerical models. These microstructural observations thus provide new insight into central uplift formation, one of the least-understood processes during complex impact crater formation, which can produce many kilometers of vertically uplifted bedrock in seconds.
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spelling curtin-20.500.11937-727382019-02-27T00:51:12Z Microstructural dynamics of central uplifts: Reidite offset by zircon twins at the Woodleigh impact structure, Australia Cox, Morgan Cavosie, Aaron Bland, Phil Mijkovic, Katarina Wingate, M. Impact cratering is a dynamic process that is violent and fast. Quantifying processes that accommodate deformation at different scales during central uplift formation in complex impact structures is therefore a challenging task. The ability to correlate mineral deformation at the microscale with macroscale processes provides a critical link in helping to constrain extreme crustal behavior during meteorite impact. Here we describe the first high-pressure-phase–calibrated chronology of shock progression in zircon from a central uplift. We report both shock twins and reidite, the high-pressure ZrSiO4 polymorph, in zircon from shocked granitic gneiss drilled from the center of the >60-km-diameter Woodleigh impact structure in Western Australia. The key observation is that in zircon grains that contain reidite, which forms at >30 GPa during the crater compression stage, the reidite domains are systematically offset by later-formed shock deformation twins (∼20 GPa) along extensional planar microstructures. The {112} twins are interpreted to record crustal extension and uplift caused by the rarefaction wave during crater excavation. These results provide the first physical evidence that relates the formation sequence of both a high-pressure phase and a diagnostic shock microstructure in zircon to different cratering stages with unique stress regimes that are predicted by theoretical and numerical models. These microstructural observations thus provide new insight into central uplift formation, one of the least-understood processes during complex impact crater formation, which can produce many kilometers of vertically uplifted bedrock in seconds. 2018 Journal Article http://hdl.handle.net/20.500.11937/72738 10.1130/G45127.1 Geological Society of America restricted
spellingShingle Cox, Morgan
Cavosie, Aaron
Bland, Phil
Mijkovic, Katarina
Wingate, M.
Microstructural dynamics of central uplifts: Reidite offset by zircon twins at the Woodleigh impact structure, Australia
title Microstructural dynamics of central uplifts: Reidite offset by zircon twins at the Woodleigh impact structure, Australia
title_full Microstructural dynamics of central uplifts: Reidite offset by zircon twins at the Woodleigh impact structure, Australia
title_fullStr Microstructural dynamics of central uplifts: Reidite offset by zircon twins at the Woodleigh impact structure, Australia
title_full_unstemmed Microstructural dynamics of central uplifts: Reidite offset by zircon twins at the Woodleigh impact structure, Australia
title_short Microstructural dynamics of central uplifts: Reidite offset by zircon twins at the Woodleigh impact structure, Australia
title_sort microstructural dynamics of central uplifts: reidite offset by zircon twins at the woodleigh impact structure, australia
url http://hdl.handle.net/20.500.11937/72738