Geological history of the Waukarie Creek canyon complex, southern Flinders Ranges, South Australia

Abstract

Many regional disconformities or 'sequence boundaries' have now been identified throughout the late Proterozoic Wilpena sediments of the Adelaide Geosyncline, South Australia. The most prominent of these appears near the base of the Wonoka Formation and has been related to the formation of incised valleys or 'canyons'. Early interpretations of these canyons suggested they were of submarine origin, cut and filled in a deepwater environment. However, more recent work has focused on a subaerial model whereby the incisions were cut fluvially. Work was carried out on the Waukarie Creek Canyon Complex in the Southern Flinders Ranges. Observations gained from field mapping tend to favour a subaerial origin for canyon development. Some localities were found that provide evidence that there was some tectonic activity, expressed by deformation of sediments, prior to the formation of the Wonoka canyons. Palaeocurrents from flute casts and current ripples show that numerous reversals were found throughout the canyon, substantiating a tectonic influence on the formation of the canyons. This activity may be approximately coeval with the Beardmore Orogeny of Antarctica. The compressional Cambro-Ordovician Delamerian Orogeny subsequently deformed the sedimentary prism in a complex array of north-south trending tight folds and reverse faults.