Australasian impact crater buried under the Bolaven volcanic field, Southern Laos

1Kerry Sieh,1Jason Herrin,2Brian Jicha, 1Dayana Schonwalder Angel,1James D. P. Moore, 1Paramesh Banerjee,3Weerachat Wiwegwin, 4Vanpheng Sihavong,2Brad Singer,3Tawachai Chualaowanich,5Punya Charusiri
Proceedings of the National Academy of Sciences of the United States of America (PNAS)(In Press) Link to Article [DOI:https://doi.org/10.1073/pnas.1904368116]
1Earth Observatory of Singapore, Nanyang Technological University, 639798 Singapore;
2Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706;
3Department of Mineral Resources, Ministry of Natural Resources and Environment, Ratchatewi, 10400 Bangkok, Thailand;
4Department of Geology and Mines, Ministry of Energy and Mines, Vientiane, Lao People’s Democratic Republic;
5Department of Geology, Chulalongkorn University, Khet Pathumwan, 10330 Bangkok, Thailand

The crater and proximal effects of the largest known young meteorite impact on Earth have eluded discovery for nearly a century. We present 4 lines of evidence that the 0.79-Ma impact crater of the Australasian tektites lies buried beneath lavas of a long-lived, 910-km3 volcanic field in Southern Laos: 1) Tektite geochemistry implies the presence of young, weathered basalts at the site at the time of the impact. 2) Geologic mapping and 40Ar-39Ar dates confirm that both pre- and postimpact basaltic lavas exist at the proposed impact site and that postimpact basalts wholly cover it. 3) A gravity anomaly there may also reflect the presence of a buried ∼17 × 13-km crater. 4) The nature of an outcrop of thick, crudely layered, bouldery sandstone and mudstone breccia 10–20 km from the center of the impact and fractured quartz grains within its boulder clasts support its being part of the proximal ejecta blanket.

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