40Ar/39Ar laser probe dating of the Central European tektite-producing impact event

A new 40Ar/39Ar data set is presented for tektites from the Central European strewn field (moldavites). This is the only strewn field that is entirely situated in a continental environment, and still characterised by scattered ages (14-15.3 Ma). The main objectives of the study were to define more precisely the moldavite formation age and provide a good calibration for a glass standard proposed for fission-track dating. The laser total fusion ages obtained on chips from seven individual specimens from the Southern Bohemian and Moravian subfields are restricted to a narrow interval of time, with an average of 14.34 ± 0.08 Ma relative to the 27.95 ± 0.09 Ma of the Fish Canyon Tuff biotite. This result gives a more precise age not only for the tektite field but also for its producing impact. If the genetic link between the moldavites and the Nördlinger Ries impact crater is maintained, then this new age has to be considered a reliable estimate for the Ries crater also. This new value places the formation of Central European tektites within the Lower Serravallian, in the latest geologic timescales. Evidence of their impact products, such as glass spherules or shocked minerals, can therefore be sought in sedimentary marine formations in a more precisely defined age interval.