The Magnitude of Exhumation in the Kidson Sub-basin, Western Australia, using Thermal and Compaction Techniques

Abstract

The Kidson Sub-basin which forms the largest tectonic province of the Canning Basin has a high potential for Uranium, sediment-hosted base metals, conventional and unconventional hydrocarbons. The basin has undergone major tectonic events since its formation in the Early Ordovician involving several inversion episodes resulting in extensive exhumation in the basin. The magnitude, timing and distribution of exhumation associated with these inversion episodes are poorly studied due to sparse data in the area. In this study, we integrate recently acquired seismic data with existing well data, combining for the first time thermal and compaction techniques to constrain the magnitude and distribution of exhumation associated with these major inversion episodes. Our results indicate that 300 to 500 m of exhumation occurred during the middle Silurian to Early Devonian inversion episode or Prices Creek Compression, 500 to 750 m of exhumation occurred during the middle Carboniferous inversion episode or Meda Transpression and 800 to 1200 m of exhumation occurred during the Late Triassic to Early Jurassic inversion episode or Fitzroy Transpression. Data from apatite fission-track analysis put temporal constraints on the timing of this exhumation and indicate that cooling from maximum post-depositional temperatures within the Kidson Sub-basin occurred in the Late Triassic to Early Jurassic. This imply that a paleothermal maximum was reached within the Kidson Sub-basin during the Early Triassic extension episode, prior to the Fitzroy Transpression. During this period, we also detect that the sediments were affected by a slight increase in basal heat flow associated with the rifting event. Results illustrate that during each of these inversion events, higher amounts of exhumation affected the Kidson Sub-basin than previously thought. The results from this study also demonstrate two dominant factors controlling the spatial and temporal distribution of exhumation in the Kidson Sub-basin. We suggest that the spatial distribution of exhumation in the sub-basin during each inversion episode was dominantly controlled by variation in rheology (strength) of inherited basement units, whilst the temporal distribution of exhumation was dominantly controlled by variation in the magnitude of compressive stress.