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

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 Be-10 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.

Automated summary

This paper questions the plausibility of the recently proposed impact site for Australasian tektites in the Bolaven volcanic field in Southern Laos by demonstrating problems with the presented evidence. It shows the geochemical incompatibility of the tektite composition with the proposed source materials and raises doubts about the size of the putative crater and signs of postimpact lava flows. It also remarks on the shortcomings of the current consensus location in Indochina for the impact site of Australasian tektites.