Abstract:

While there is a well-established general theory for the mechanism of excavation of hypogene caves in artesian basins, the same cannot be said for hypogene caves in deformed strata. A few active thermal caves, several dormant hypogene caves and many extinct hypogene caves and extinct hypogene sections of complex multiprocess caves are developed in impounded karsts along the whole length of the Tasman Fold Belt System in eastern Australia. The active caves are related to warm springs with temperatures (20°-28°C) only a few degrees above the annual average (17°C) and are often cooler than the external summer temperature. The origins of these waters have not been investigated, but most active, dormant, extinct and suspect ancient hypogene caves occur in close proximity to faults, frequently to large regional faults. If and how water from these faults is transmitted to the propagation planes in the caves is not known. While hypogene speleothems occur in the active and dormant caves, these are absent from the older suspect hypogene caves, some of which have probably been thermally dormant for hundreds of millions of years. The older caves are characterized by cave pattern, the presence of hypogene speleogens and poor relationship with surrounding hydrology. Two processes that are signi?cant in the development of the older complex caves are integration, which leads to formerly separate cavities joining to form larger caves and renovation, which smoothes cave walls, obliterating boxwork, etching and lithologically selective solution.