Resumen de Constraining the evolution of drainage divides during and after breakup by coupling low temperature thermochrometers at Bathurst (New South Wales)
C. Persano, Finlay M. Stuart, P. Bishop, D. Botor
Apatite fission track thermochronology (AFTT) has revealed that the Australian plateau was not affected by the opening o f the Tasman Sea, occurred at about 90 Ma. However, there are regions in the highlands, such as the Bathurst batholith in NSW, where AFT ages correspond with the time o f break-up. He ages on both side o f the CDD range between 90 and 110 Ma, and they show positive correlation with elevation. We have modelled the AFT data with Monte Trax and used the resulting cooling histories to predict He ages using a forward model based on diffusion o f He in apatite. These data suggest that the Jlanks o f the continental drainage divide experienced different cooling histories at the time o f break-up (about 200m/Ma for the eastern flank and 30m Myr for the western side), but samples now exposed were at about 40°C no later than 80 ± 5 Ma. The rapid denudation o f the eastern flank during time o f break-up can be related to reactivation o f Palaeozoic faults or to the opening o f the Tasman Sea. However the He ages strongly suggest that the CDD has been stable for, at least, the last 80 Ma.
