Precise radiometric age establishes Yarrabubba, Western Australia, as Earth's oldest recognised meteorite impact structure.

ABSTRACT: 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?×?10¹³ to 5.0?×?10¹⁵ kg of H₂O vapour instantaneously into the atmosphere. These results provide new estimates of impact-produced H₂O vapour abundances for models investigating termination of the Paleoproterozoic glaciations, and highlight the possible role of impact cratering in modifying Earth's climate.

SUBMITTER: Erickson TM 

PROVIDER: S-EPMC6974607 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature