Abstract:

Thermal histories modeled from apatite fission-track( FT) data are dependent upon the annealing behavior of apatite fission-tracks. It has been confirmed that the rate of fission-track annealing correlates with apatite structure and the annealing rate is faster for fission-tracks with higher angle to crystallographic C axis，so different rates of fission-track annealing will eventually lead to different length distributions. In this study, the apatite fission-track length C axis projection model was used to eliminate the effects of different angles to crystallographic C axis，and then the difference of thermal histories modeled from apatite fission-tracks with the same length and different angle to crystallographic C axis was discussed. This paper has showed that the largest difference of the maximum palaeo-geotemperatures among the modeling history amount，cooling uplift rate and initial uplift time is 430 m is 15℃，and the largest difference in the erosion and 1. 5 ℃/Ma，respectively.  And the result reveals that the largest difference of initial uplift time in each tectonic movement can reach up to 2 Ma. In the actual thermal history simulation，we should pay more attention to the influence of this parameter.  Ideally，the angles of each apatite fission-track to crystallographic C axis should be measured to improve the thermal history precision.

Key words: apatite fission-track, crystallographic orientation, thermal history simulation