Hypogene Speleogenesis in Greece

Abstract

Many hypogene caves have been recognized in several locations in Greece in the last decade. Their identification is mostly based on morphological criteria and in some cases on geochemical evidence, including mineral and water chemistry. Several patterns of cave development have been recorded along with various small-scale morphological features. In this chapter, hypogene caves are presented per region in terms of different geotectonic units. These caves cover the whole Greek mainland and some islands of the Aegean archipelago. Their altitudinal distribution ranges from the sea level up to about 2000 m elevation. Nowadays, most caves are uplifted relicts of hydrothermal systems. The dissolution was caused mainly due to CO2-rich water, and in a few cases speleogenesis was driven by H2S. Speleogenesis in most cases took place below the water table in a deep phreatic setting, by slowly convecting waters. However, there are water-table caves, commonly related to H2S speleogenesis. It is demonstrated that hypogene speleogenesis in Greece is strongly related to the hydrothermal regime. Cave morphology, stratigraphy, hydrogeology, volcanism, tectonics, mineralogy and geochemistry are briefly discussed with respect to the structure of the Hellenic alpine orogene and its evolution.