Western Australia

Carnarvon Basin

The Carnarvon Basin contains the Nyang and Onslow Projects (Figure 1) located in the northern part of the Carnarvon Basin.  The basin is some 650km long and up to 250km wide, extending north-south along the coast of Western Australia between Geraldton in the south and Exmouth Gulf in the north.

The Carnarvon Basin contains a Palaeozoic succession below a relatively thin cover of Cretaceous and Tertiary sediments. The basement that underlies the basin consists of granites, gneisses and schists of Proterozoic age. These granites are enriched in leachable uranium. Over time, uranium has been leached from these granites and dissolved in groundwater that eventually flows into the Cretaceous and Tertiary strata flanking the eastern margin of the Basin. Chemical conditions affecting this groundwater can change as the groundwater moves from oxidized to reducing environments, resulting in the deposition of uranium mineralisation. The main host for the uranium mineralisation in this district are palaeochannels developed within the Cretaceous Birdrong Sandstone. The Birdrong thickens to the west where it becomes a major artesian aquifer and, in offshore areas of the Carnarvon Basin, the main host for petroleum and natural gas.

Figure 1. Location Plan for Carnarvon Basin Projects