Confined fission-track revelation in apatite: how it works and why it matters

Abstract. We present a new model for the etching and revelation of confined fission tracks in apatite based on variable along-track velocity, vT(x). Insights from step-etching experiments theoretical energy loss rates fragments suggest two end-member structures: constant-core, with central zone constant rate that then falls off toward track tips; linear, which fall linearly midpoint to tips. From these, we construct characterization encompasses all relevant processes, including penetration widening semi-tracks polished grain surface, intersection expansion tracks, analyst selection measure bypass. Both structures are able fit data five sets paired fossil unannealed annealed induced Durango apatite, supporting correctness our approach providing series insights into theory practice fission-track thermochronology. Etching much faster than those spontaneous impacting relative efficiency both length density measurements suggesting high-temperature laboratory annealing may induce transformation cores does not occur at geological conditions partial annealing. The quantifies how variation criteria, summarized as ratio bulk velocity etched tip (vT/vB), likely plays first-order role reproducibility measurements. It also accounts provides an estimate large proportion intersected but measured, it shows biasing is be insufficient basis predicting probability detection different populations. vT(x) optimizing conditions, linking across protocols, discerning information underlying structure tracks.