HYPOGENIC FEATURES IN MARONIA CAVE, THRACE, GREECE. EVIDENCE FROM MORPHOLOGIES AND FLUID INCLUSIONS.
The evolution of caves is usually controlled by meteoric water seepage into karst systems (epigenic process). In some cases, caves are formed by ascending fluids the aggressiveness of which is gained in depth. Such cavities are defined as hypogenic. Many caves considered previously as epigenic are now reinterpreted as hypogenic. Most Greek hypogenic caves are related with confined speleogenesis in karstic rocks near to impermeable rock exposures. At the present study the hypogenic features of the Maronia cave in Thrace of Greece, are described. The cave system is developed in a relatively thin layer of eroded Nummulitic limestones with a Middle Eocene age. Medium scale morphological characteristics such as cupolas and feeders indicate rising flow of solutions. In addition, fluid inclusion studies in selected calcite spars from the cave show elevated temperatures of formation (93 to 164ºC with two peaks at 100 and 140 ºC) from circulating hydrothermal fluids.