Dauphiné twinning as evidence for an impact origin of preferred orientation in quartzite: An example from Vredefort, South Africa

Research Article| April 01, 2005 Dauphiné twinning as evidence for an impact origin of preferred orientation in quartzite: An example from Vredefort, South Africa H.-R. Wenk; H.-R. Wenk 1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar I. Lonardelli; I. Lonardelli 1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar S.C. Vogel; S.C. Vogel 2Lujan Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA Search for other works by this author on: GSW Google Scholar J. Tullis J. Tullis 3Department of Geological Sciences, Brown University, Providence, Rhode Island 02912, USA Search for other works by this author on: GSW Google Scholar Author and Article Information H.-R. Wenk 1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA I. Lonardelli 1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA S.C. Vogel 2Lujan Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA J. Tullis 3Department of Geological Sciences, Brown University, Providence, Rhode Island 02912, USA Publisher: Geological Society of America Received: 07 Sep 2004 Revision Received: 24 Nov 2004 Accepted: 29 Nov 2004 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2005) 33 (4): 273–276. https://doi.org/10.1130/G21163.1 Article history Received: 07 Sep 2004 Revision Received: 24 Nov 2004 Accepted: 29 Nov 2004 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation H.-R. Wenk, I. Lonardelli, S.C. Vogel, J. Tullis; Dauphiné twinning as evidence for an impact origin of preferred orientation in quartzite: An example from Vredefort, South Africa. Geology 2005;; 33 (4): 273–276. doi: https://doi.org/10.1130/G21163.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Large meteorite impacts cause great changes to geologic features on Earth, ranging from cratering and ejecta blankets to phase transformations in minerals. In this report we describe the effect of a shock wave on the crystallographic orientation of quartz crystals in quartzite from the Vredefort impact site in South Africa. Preferred orientation of bulk quartzite samples was measured by time-of-flight neutron diffraction. With a random distribution of c-axes, a weak but distinct difference between the orientation distribution of positive and negative rhombs was observed, as illustrated with pole figures and inverse pole figures. Results for the natural Vredefort sample are compared with deformation experiments in which the reorientation occurs as a result of mechanical Dauphiné twinning under stress. We conclude that stresses during the impact produced twinning and that the direction of the compressive shock wave can be inferred from the preferred orientation pattern. Specifically, positive rhombs become aligned perpendicular to the direction of compressive stress. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.