Hypogene Caves of the Tasmanic Karsts of Eastern Mainland Australia

Abstract

The Tasmanic karsts of eastern Australia extend from the south-eastern tip of Tasmania to the far north of Queensland. The mainland section incorporating the eastern parts of Victoria, New South Wales and Queensland contains more than one hundred and twenty bodies of cavernous Palaeozoic limestone, most of which form impounded karsts. Many of these karst areas are small, difficult to access, contain a small number of caves and have received little attention from cavers and even less attention from scientists. Some 21 karst areas stand out for their number of caves and their diversity of underground features. Almost all of the Tasmanic caves in mainland Australia show a high degree of structural guidance and are developed in massive high-purity limestone. Solution dolines are rare or absent in the surrounding karst. Some caves appear to have been formed entirely by a single hypogenic event while others have been modified by several hypogenic events (multiphase caves). In other caves, hypogene forms have been overprinted by later epiphreatic, paragenetic, fluvial and breakdown events (multiphase/multiprocess caves). Where there are active rivers in the caves, the rivers are often much smaller than the cavities they flow through, take complex paths through the rock and are captured into pre-existing cavities. The evidence for a hypogene origin of these caves is largely morphological, but is supported by circumstantial evidence such as intersection of palaeokarst, proximity to regional faults and tenuous relationships with the surrounding geomorphology and hydrology.

This chapter is dedicated to the memory of the recently deceased Ken Grimes (1944–2016) a pioneer and major contributor to the geological study of Australian caves.