Speleogenesis in aeolian calcarenite: A case study in western Victoria

Most studies of karst landscapes and their processes have been concerned with consolidated, often well-jointed limestones. There are particular problems involved in the study of karst procesess in softer, less-compact limestones such as chalk, coral reefs, and aeolian calcarenite. Previous studies in aeolian calcarenite indicated these problems and a scheme was developed of speleogenesis in aeolian calcarenite. A study of karst processes in aeolian calcarenite at Bats Ridge in western Victoria has developed this scheme further. The karst features and processes at Bats Ridge are an integral part of the landscape of a mid-Pleistocene calcarenite dune system. The resolution of problems of the rapid subaerial speleogenesis in the area is achieved by the synthesis of the known karst features of the ridge and the geology and geomorphology of the area. Karst development on this aeolianite ridge depends on lithological conditions as well as the availability of aggressive water capable of solution. The diagenesis of the calcarenite is occurring now and must have been occurring by the mid-Pleistocene. This simultaneous lithification of the carbonate dunes into aeolian calcarenite rock and the development of solutional karst features in the dunes is the characteristic feature of the speleogenesis in this area. It is the formation of a hardened kankar layer (cap rock) in the dunes of sufficient compressive and tensile strength to support cavities, which is the result of these interrelated factors, that has strongly determined the formation of the karst features.