| Autor: |
Erickson TM; Jacobs-JETS, Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX, 77058, USA. Timmons.M.Erickson@nasa.gov.; The Institute for Geoscience Research (TIGeR), Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box 1984, Perth, WA, 6845, Australia. Timmons.M.Erickson@nasa.gov.; Center for Lunar Science and Exploration, Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Blvd, Houston, TX, 77058, USA. Timmons.M.Erickson@nasa.gov., Kirkland CL; The Institute for Geoscience Research (TIGeR), Centre for Exploration Targeting-Curtin Node, School of Earth and Planetary Sciences, Curtin University, GPO Box 1984, Perth, WA, 6845, Australia., Timms NE; The Institute for Geoscience Research (TIGeR), Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box 1984, Perth, WA, 6845, Australia., Cavosie AJ; The Institute for Geoscience Research (TIGeR), Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box 1984, Perth, WA, 6845, Australia., Davison TM; Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, London, SW7 2AZ, UK. |
| Abstrakt: |
The ~70 km-diameter Yarrabubba impact structure in Western Australia is regarded as among Earth's oldest, but has hitherto lacked precise age constraints. Here we present U-Pb ages for impact-driven shock-recrystallised accessory minerals. Shock-recrystallised monazite yields a precise impact age of 2229 ± 5 Ma, coeval with shock-reset zircon. This result establishes Yarrabubba as the oldest recognised meteorite impact structure on Earth, extending the terrestrial cratering record back >200 million years. The age of Yarrabubba coincides, within uncertainty, with temporal constraint for the youngest Palaeoproterozoic glacial deposits, the Rietfontein diamictite in South Africa. Numerical impact simulations indicate that a 70 km-diameter crater into a continental glacier could release between 8.7 × 10 13 to 5.0 × 10 15 kg of H 2 O vapour instantaneously into the atmosphere. These results provide new estimates of impact-produced H 2 O vapour abundances for models investigating termination of the Paleoproterozoic glaciations, and highlight the possible role of impact cratering in modifying Earth's climate. |
