Flood deposits penecontemporaneous with ∼0.8 Ma tektite fall in NE Thailand: impact-induced environmental effects?

Abstract

Although a crater is not yet identified, the Australasian tektite strewn field provides evidence that a major impact cratering event took place in the Southeast Asian region at ∼0.8 Ma, just prior to the Brunhes/Matuyama geomagnetic polarity reversal. Paleomagnetic evidence including reversed polarity in mud lens closely associated with in situ tektites suggests that tektite-bearing flood deposits near Ban Ta Chang and Chum Phuang in northeast Thailand are penecontemporaneous with the impact event. The deposits include abundant organic debris, including whole tree trunks and mammal bones, that preserved due to reducing conditions, which are also responsible for the presence of abundant iron sulphides. Sedimentological observations suggest a series of major flood events that are out of character with the modern meandering river system to which they are related. The deposits are consistent with the effects of regional deforestation, increased run off and erosion, and other environmental disruptions expected in the aftermath of a major impact event. © 2004 Elsevier B.V. All rights reserved.