Long‐Term Landscape Evolution of the Northparkes Region of the Lachlan Fold Belt, Australia: Constraints from Fission Track and Paleomagnetic Data: A Discussion

Abstract

O’Sullivan et al. (2000) provide some interesting arguments regarding the landscape evolution of the Northparkes region in Australia. Their model is impressive and illustrates that unraveling the evolution of a landscape can be a complex business. Their figure 8 provides a good summary of their model and its implications for landscape evolution. The Carboniferous age for weathering is based on paleomagnetically dated saprolite in which the hematite occurs as fine crystals dispersed throughout it. They postulate this weathering profile has been covered by no less than up to 6 km of sediments between the Carboniferous and present including ≈3.5 km between late Carboniferous and mid-Permian and between 1.4 and 2.5 km during the midTriassic to early Tertiary. None of these sediments currently exist in the local region from which the data were accumulated by O’Sullivan et al. (2000), but examples used by them from the broader region are clastic sediments, many of which contain significant coal and other organic compounds. Perhaps the most appropriate model to use in reconstructing the “missing” sediments over the Northparkes mine is the Great Artesian Basin and the Cooper Basin underlying it, both being composed of Permian to mid-Cretaceous sedimentary sequence, probably similar to those that are now