Earth’s oldest recognized meteorite impact structure

Precise radiometric age establishes Yarrabubba, Western Australia, as Earth’s oldest recognised meteorite impact structure (Research work by Erickson et al.)

Composite aeromagnetic anomaly map of the Yarrabubba impact structure within the Yilgarn Craton, Western Australia, showing the locations of key outcrops and samples used in this study. The image combines the total magnetic intensity (TMI, cool to warm colours) with the second vertical derivative of the total magnetic intensity (2VD, grayscale) data. The demagnetized anomaly centred on the outcrops of the Barlangi granophyre is considered to be the eroded remnant of the central uplift domain, which forms the basis of the crater diameter of 70 km. Prominent, narrow linear anomalies that cross-cut the demagnetized zone with broadly east-west orientations are mafic dykes that post-date the impact structure.  

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. The ~70 km-diameter Yarrabubba impact structure in Western Australia has previously been regarded as among Earth’s oldest meteorite craters but has hitherto lacked absolute age constraints. Here, the authors determine a precise impact age of 2229 ± 5 Ma, which extends the terrestrial cratering record back in time by > 200 million years and establishes Yarrabubba as the oldest recognised meteorite impact structure on Earth.

Original article: Precise radiometric age establishes Yarrabubba, Western Australia, as Earth’s oldest

recognised meteorite impact structure. DOI:  10.1038/s41467-019-13985-7. To read the article click here.