800,000 years ago, the impact of a large asteroid in Indochina projected a large quantity of drop-shaped or teardrop-shaped fragments of glassy rocks, known as tektites, resulting from the continental surface fusion throughout Southeast Asia and as far as Antarctica. A particular type of tektite called "Muong Nong" (named after the locality situated in the East of Savannakhet in Laos) provides new indications on the preservation of very high-pressure polymorph of silica called "coesite".
Published in Nature Scientific reports and based on the study of samples collected near Muong Nong in the 1990s by an American team and in February 2019 by a Franco-Laotian team, the study reveals the missing answer to explain the preservation of coesite in these glasses, even though the temperature conditions recorded theoretically predicted its disappearance.
The article, entitled « 3D tomographic analysis reveals how coesite is preserved in Muong Nong-type tektites » is now available online.
Mission participants, funded by the A*MIDEX foundation and supported by IRD Laos, are Pierre Rochette (professor at Aix-Marseille University) and Southone Singsoupho (professor at the University of Laos in Vientiane).