High-precision argon dating was used to analyze tektites and bentonites derived from a bolide impact associated with the mass extinction event at the boundary of the Cretaceous and Paleogene periods.
Time Scales of Critical Events Around the Cretaceous-Paleogene Boundary, Renne PR. et al, Science, 8 Feb 2013, pp. 684-687
Time Scales of Critical Events Around the Cretaceous-Paleogene Boundary, Renne PR. et al, Science, 8 Feb 2013, pp. 684-687