Beryllium-10 in Australasian tektites: constraints on the location of the source crater

By using accelerator mass spectrometry we have measured the Be-10 concentrations of 86 Australasian tektites. Corrected to the time of tektite production similar to0.8 My ago, the Be-10 concentrations (10(6) atom/g) range from 59 for a layered tektite from Huai Sai, Thailand, to 280 for an australite from New South Wales, Australia. The average value is 143 +/- 50. When tektites are sorted by country, their average measured Be-10, concentrations increase slowly with increasing distance from Southeast Asia, the probable location of the tektite producing event, from 59 +/- 9 for 6 layered tektites from Laos to 136 +/- 20 for 20 splash-form tektites from Australia. The lowest Be-10 concentrations for tektites fall on or within a contour centered off the shore of Vietnam, south of the Gulf of Tonkin (107degreesE; 17degreesN), but also encompassing two other locations in the area of northeastern Thailand previously proposed for the site of a single tektite-producing impact. The Be-10 concentrations of layered tektites show only a weak anticorrelation (R similar to -0.3) with the numbers of relief crystalline inclusions.