The Age of Earth’s Most Enigmatic Asteroid Impact Identified

Three small ‘australites’, tektites found in Australia. These and other tektites of the large Australasian strewn field were produced during an impact event roughly 788 thousand years ago. Despite its geologically young age, the source crater of the tektites is still unknown. Samples and image: Martin Schmieder, LPI.

Three small “australites” (tektites found in Australia). These and other tektites of the large Australasian strewn field were produced during an impact event roughly 788 thousand years ago. Despite its geologically young age, the source crater of the tektites is still unknown. Samples and image: Martin Schmieder, LPI.

The origin of the Australasian tektites, droplets and lumps of melted Earth rock, is arguably among the most enigmatic geologic event of the Earth’s last million years. They were produced by an asteroid impact strong enough to melt the target rock and scatter the melt droplets across large parts of Southeast Asia, Australia, the Pacific Ocean, the Indian Ocean, and Antarctica. Yet, despite its geologically young age, the source crater of the Australasian tektites still awaits its discovery. A new argon isotopic study led by Fred Jourdan at Curtin University in Perth, Australia reports a very precise age for the tektite-producing impact event – at 788,000 ± 3,000 years ago. The glass analyses, moreover, suggest the airborne impact melt was quite hot, reaching temperatures between 2,350 and 4,000 °C. Knowing the age of this impact event will help in finding the source crater for these Australasian tektites.

Source: Jourdan, F., Nomade, S., Wingate, M.T., Eroglu, E. and Deino, A., Ultraprecise age and formation temperature of the Australasian tektites constrained by 40Ar/39Ar analyses. Meteoritics & Planetary Science (in press).

 

 

 

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