Tektite production as a standard process in large terrestrial impact craters

Tektites are terrestrial macroscopic silica-rich glasses generated by meteoritic impacts. We propose here an up-to-date review of the characteristics of tektites considering the three newly documented strewn fields. Diagnostic criteria that make sense in terms of a common genetic process emerge from these characteristics and enable their discrimination from other types of impact-glass strewn fields. The seven strewn fields that qualify include the four classic ones (Australasian, Central European, Ivory Coast and North American) plus ananguite, belizite and geraisite strewn fields. Their age spans the 0.8 to 35 Ma range. In addition, the urengoite case is considered to be a strong candidate for a tektite strewn field despite the low number of finds. If one also considers the uruguaite putative candidate strewn field and the three microtektite-only strewn fields, the age span extends to the Cretaceous–Paleogene (K–Pg) layer. The number of known impact craters with diameters >10 km and well-defined ages younger than 66 Ma is fifteen. In addition, six impact events, for which no craters have yet been found, may have produced strewn fields during the 0–66 Ma interval. Therefore, 57% of large impact events in the 0–66 Ma period may have produced tektites or microtektites. Restricting the count to only the seven proven tektite strewn fields, the proportion is 39%. This figure drops to zero for known craters older than 66 Ma. On the other hand, of the large known or presumed craters, 100% of those younger than 3 Ma and 88% of those younger than 30 Ma have generated tektites. Therefore, considering the increasing probability of tektite strewn fields to be erased through time, we conclude that tektite production is likely the rule rather than the exception in large terrestrial impact craters.