Abstract:

Among the ca. 14,000 registered caves of Austria few have been attributed to hypogene speleogenesis. This paper provides an overview of hypogene caves in Austria. A few dozen examples are known around the Vienna Basin. Some of these caves, such as Eisensteinhöhle and Nasser Schacht, display a thermally anomalous microclimate and are associated with thermal springs. Other caves are inactive, but their morphology and deposits are suggestive of a hypogene origin. Preliminary morphologic observations suggest sulfuric speleogenesis for Stephanshöhle near Bad Deutsch Altenburg. In the Northern Calcareous Alps, which host the majority of caves of Austria, only very few have previously been identi?ed as hypogene (e.g., Märchenhöhle, Wasserhöhle), but the number of such caves is likely to increase in the near future. Also, “normal” (epigenetic) cave systems sometimes show morphological evidence suggestive of a hypogene origin, but conclusive proof is lacking. The only Austrian cave where a sulfuric acid speleogenesis is well documented is Kraushöhle. In marbles of the Central Alps lukewarm and thermal springs are present and cavities of likely hypogene origin were encountered during tunnel construction near Lend. In a nearby cave, Entrische Kirche, isotopic evidence of marble alteration by warm paleowaters was recently identi?ed. Extensive calcite deposits are also known from nearby Stegbachgraben, and ongoing isotopic and fluid-inclusion studies strongly suggest hypogene water-rock interaction at lukewarm (<40°C) temperatures there. A few caves in the Southern Calcareous Alps also show morphological evidence of a hypogene origin (e.g. Kozakhöhle), which is U/Th-dated to older than ca. 144,000 years. CO2 -rich springs discharge nearby.