Dating the shock wave and thermal imprint of the giant Vredefort impact, South Africa

Abstract

Research Article| January 01, 1997 Dating the shock wave and thermal imprint of the giant Vredefort impact, South Africa D. E. Moser D. E. Moser 1Jack Satterly Geochronology Laboratory, Royal Ontario Museum, Toronto M5S 2C6, Canada Search for other works by this author on: GSW Google Scholar Geology (1997) 25 (1): 7–10. https://doi.org/10.1130/0091-7613(1997)025<0007:DTSWAT>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation D. E. Moser; Dating the shock wave and thermal imprint of the giant Vredefort impact, South Africa. Geology 1997;; 25 (1): 7–10. doi: https://doi.org/10.1130/0091-7613(1997)025<0007:DTSWAT>2.3.CO;2 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 U-Pb geochronology of single grains of zircon and monazite has been used to date an episode of intense postimpact metamorphism in the core of the deeply eroded Vredefort impact structure of South Africa. Results from two basement units exposed in the uplifted central region indicate that the impact and a later pyroxene hornfels metamorphic event were penecontemporaneous at 2020 ± 3 Ma. Discovery of a synimpact to postimpact dike of norite that intruded at 2019 ± 2 Ma is the first recognition of mafic igneous activity related to impact. The dike is either derived from a Sudbury-type impact melt layer (since eroded) or is the product of decompression melting of Kaapvaal mantle in response to the ablation of >15 km of crust at the center of the crater. The combined heating effects of the shock wave and impact-triggered magmas are thought to have created the 300 km2 thermal imprint of the asteroid collision with Kaapvaal craton, and account for the nearly coeval timing relationship between core metamorphism and shock revealed by this study. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.