Thermal-metamorphic signature of an impact event in the Vredefort dome, South Africa

Research Article| September 01, 1998 Thermal-metamorphic signature of an impact event in the Vredefort dome, South Africa Roger L. Gibson; Roger L. Gibson 1Department of Geology, University of the Witwatersrand, WITS, Johannesburg 2050, South Africa Search for other works by this author on: GSW Google Scholar W. Uwe Reimold; W. Uwe Reimold 1Department of Geology, University of the Witwatersrand, WITS, Johannesburg 2050, South Africa Search for other works by this author on: GSW Google Scholar Gary Stevens Gary Stevens 2Economic Geology Research Unit, University of the Witwatersrand, WITS, Johannesburg 2050, South Africa Search for other works by this author on: GSW Google Scholar Author and Article Information Roger L. Gibson 1Department of Geology, University of the Witwatersrand, WITS, Johannesburg 2050, South Africa W. Uwe Reimold 1Department of Geology, University of the Witwatersrand, WITS, Johannesburg 2050, South Africa Gary Stevens 2Economic Geology Research Unit, University of the Witwatersrand, WITS, Johannesburg 2050, South Africa Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1998) 26 (9): 787–790. https://doi.org/10.1130/0091-7613(1998)026<0787:TMSOAI>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Roger L. Gibson, W. Uwe Reimold, Gary Stevens; Thermal-metamorphic signature of an impact event in the Vredefort dome, South Africa. Geology 1998;; 26 (9): 787–790. doi: https://doi.org/10.1130/0091-7613(1998)026<0787:TMSOAI>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 Pseudotachylitic breccias and shock deformation features related to the 2.02 Ga formation of the Vredefort dome by meteorite impact were overprinted by a static metamorphic event, the intensity of which decreased from granulite-facies (T ≥700 °C) in the center of the dome to greenschist-facies (T ≤400 °C) around its margins. Geobarometric estimates of 0.2–0.3 GPa for the metamorphic parageneses indicate some 8–11 km of erosion since the impact event. The strong lateral thermal gradient implied by these P-T results is attributed to the combined effects of differential uplift of mid-crustal rocks heated along a pre-impact geotherm and increased shock heating of the target crust toward the center of the impact structure. We suggest that the exceptionally high grade of metamorphism in the center of the dome may, in part, reflect an elevated regional geothermal gradient of ∼25 °C/km in the target crust due to lingering thermal effects related to the 2.05–2.06 Ga Bushveld magmatic event. 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.