Statistical modelling of thermal annealing of fission tracks in zircon

We re-analyse the data of Yamada et al. (1995b) which represent the first substantial published experiments on thermal annealing of fission tracks in zircon, We use an improved approach to the statistical modelling of the relation between track length, temperature and time that has recently been developed for fission tracks in apatite. There are several advantages to our new approach: we distinguish between unannealed and induced tracks; we partition the residual Variance into ''within'' and ''between'' components corresponding to sampling error and extraneous sources of variation; we allow for different numbers of tracks in the experiments; and we use the information even in those cases where no tracks are seen. Our conclusions differ somewhat from those of Yamada et al. (1995b) in that we find that the data are not extensive enough to distinguish clearly between competing models. There is a need for further experiments to be planned and carried out, and we make some recommendations on their design. (C) 1997 Elsevier Science B.V.