Tectonic setting and basin evolution of the Bangemall Supergroup in the northwestern Capricorn Orogen

The Mesoproterozoic Bangemall Supergroup is the youngest depositional element within the Capricorn Orogen and comprises ∼4 to 10 km of fine-grained siliciclastic and carbonate sedimentary rocks. This succession is intruded by two generations of dolerite sills with ages of 1465 and 1070 Ma. Field studies and geochronological data support a two-fold subdivision of the Bangemall Supergroup into the c. 1620–1465 Ma Edmund Group, and the c. 1400–1070 Ma Collier Group. The principal syndepositional structural elements are parallel to the trend of major structures in the underlying Ashburton Fold Belt and Gascoyne Complex. These structures include the Talga Fault, the faulted southwestern limb of the Wanna Syncline, the Lyons River Fault, and the northwest-trending fault system that bounds the Mangaroon and Ti Tree Synclines. The Bangemall Supergroup can be divided into six depositional packages defined by basal unconformities or major marine flooding surfaces. Packages 1–4 make up the Edmund Basin and consist of carbonate and siliciclastic shelf to basinal facies that are strongly controlled by synsedimentary movement along northwest-trending basement faults. Source areas for the siliciclastic rocks were to the northwest, northeast and southeast. During deposition of Packages 5 and 6, which form the Collier Basin, the influence of the basement faults was less marked and the basin was filled with deltaic to deep-marine siliciclastic facies that were derived from the northwest and southeast. The Bangemall Supergroup has been frequently compared with Proterozoic successions in northern Australia, but these successions are either too old or imprecisely dated to make meaningful correlations. In addition, the West and North Australian Cratons may not have been joined until the assembly of Rodinia in the late Mesoproterozoic.