Quest for the Australasian impact crater: Failings of the candidate location at the Bolaven Plateau, Southern Laos

1,2Jiří Mizera
Meteoritics & Planetary Science (in Press) Link to Article []
1Nuclear Physics Institute, Czech Academy of Sciences, Řež 130, 250 68 Husinec-Řež, Czech Republic
2Institute of Rock Structure and Mechanics, Czech Academy of Sciences, V Holešovičkách 41, 182 09 Praha 8, Czech Republic
Published by arrangement with John Wiley & Sons

The quest for the parent impact structure for Australasian tektites (AAT) has remained without solution for almost a century. The present paper doubts the plausibility of the recently proposed location of the impact site at the Bolaven volcanic field in Southern Laos by showing problems with most of the presented lines of evidence. The geochemical incompatibility of the AAT composition with a mixture of weathered basalts and Mesozoic sandstones that were proposed as source materials of AAT is demonstrated by a two-component mixing calculation for major element oxides and the Nd-Sr isotopic system. Deficiency of the basaltic component as a source of Ni, Co, Cr, and 10Be in AAT and inconsistency with trends observed for O and Pb isotopes are shown. The size of the putative crater, conclusiveness of a gravity anomaly identification, signs of complete crater burial by postimpact lava flows, and identification of proximal ejecta blanket are doubted. Remarks on the shortcomings of the current consensus location of an impact site for AAT in Indochina are presented.


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