Resumen de Apatite fission tracks and (U-Th)/He thermochronology constraints on the development of the Great Escarpment on the southeastern Australian passive margin
C. Persano, Finlay M. Stuart, P. Bishop, T. Dempster
Great escarpments are erosional features that characterise all high elevation passive margins. We have used apatite fission tracks (AFT) and (U-Th)/He thermochronology to constrain the evolution ofthe Great Escarpment on southeastern Australian passive margin since the time o f break-up, occurred at about 90 Ma. Models o f escarpment evolution have been suggested in the past, but they are predominantly qualitative and the debate on how escarpments evolve is still open. We have collected samples from three transects, two perpendicular and one parallel to the coast and here we present our AFT and He age results. We have used a forward model to predict He ages for the different models and compared our results with the predicted He ages. Our results are inconsistent with a downwarping model and they require either a rapid retreat o f the escarpment or a rapid degradation o f the coastal plain and the formation o f the escarpment in its present position no later than about 50 Ma after break-up.
