Understanding the Origin and Evolution of Jenolan Caves: The Next Steps

Abstract

The dating of cave and surficial sediments by Osborne et al. (2006) indicated that some sections of Jenolan Caves, particularly the large chambers, formed in the Early Carboniferous before deposition of sediments dated at 340 Ma. The dating also identified younger mass-flow sediments, dated at 303Ma and secondary fine illite, dated at 258 Ma and 240 Ma indicating burial of the caves under the Sydney Basin. These dates meant that a new chronology for cave development at Jenolan is required to supersede that of Osborne (1996b). Construction of this chronology raises new questions: Did the paragenetic conduits form before deposition or after stripping of the Sydney Basin? Caymanites (marine carbonate turbidite palaeokarst) appear to be older than 340 Ma, but does this make palaeogeographic sense? The Early Carboniferous dates give us a beginning for the history of the present caves at Jenolan, but much of the story is missing. Many obvious features in the caves have not been studied. Present knowledge of the developmental history, palaeokarst and sediment stratigraphy, morphology and mineralogy of tourist caves at Jenolan Caves is insufficient to support sound conservation, management, development and interpretation. The next step in understanding Jenolan Caves is a structured program of dating, geological, mineralogical and geomorphic studies.