New fission-track age determinations on impact glasses

Four samples from Libyan Desert glass, one sample from Muong-Nong-type tektite, labelled Guang-Dong, and one sample from Czech Moldavite were analysed using the fission-track dating method. The Moldavite was unaffected by partial thermal track annealing, whereas the ages of Libyan Desert glass and Guang-Dong tektite appear to have been thermally lowered. Fission-track ages of the latter impact glasses were corrected using the plateau method. Apparent ages of Libyan Desert glass (between 26.0 +/- 1.8 Ma and 29.0 +/- 1.8 Ma) and Guang-Dong tektite (0.61 +/- 0.05 Ma), as well as plateau ages (weighted mean: 28.5 +/- 0.8 Ma for Libyan Desert glass and 0.77 +/- 0.08 Ma for Guang-Dong) resulted in close agreement with previous determinations published in the late 1970s by Storzer and Wagner (1977). The age of the Moldavite (15.2 +/- 0.08 Ma) also resulted in agreement with previous fission track and K-Ar determinations.