Morphological features and formation conditions of The Almopia Speleopark caves (Loutra Almopias, N. Greece)

Abstract

The Almopia Speleopark caves are located at the Almopia basin in northern Greece, at the foothill of Voras Mountain, and are formed in the Maestrichtian limestones of the Pelagonian zone. They are studied on the basis of their meso- and micro-scale morphology as well as their horizontal pattern, in order to investigate the character of the forming aquifer. Emphasis is given on the morphological description of the Loutra Almopias Cave. Cave morphology is dominated by the presence of cupolas, rock bridges, ridges and “windows”, abrupt terminations of fracture guided passages, pendants, rising channels, pseudonotches, false-floors and spongework. Speleogens indicate a speleogenesis due to slowly natural convecting hot water bodies. Phreatic calcite from the Varathron Cave is analyzed on the basis of the fluid inclusions in order to investigate the physicochemical conditions of the convecting water bodies. This has shown that the calcite was formed at temperatures ranging between 120 and 189 ºC, with a peak around 150 ºC. The fluids were dominated by NaCl of very low salinities (0.2-1.0 wt% NaCl equiv.), showing probably the incorporation of meteoric waters.