Speleothems and Biomineralization Processes in Hot Spring Environment: The Case of Aedipsos (Edipsos), Euboea (Evia) Island, Greece

Caves with hot springs and speleothem deposits are infrequent environments of high scientific interest due to their unique environmental conditions. The selected site is a small open cave spring stalactites in the Aedipsos area (NW Euboea Island, Greece), which was studied through an interdisciplinary approach. mineralogical composition speleothems determined by optical microscopy, XRD, SEM-EDS microanalysis, identification Cyanobacteria species made based on morphological characteristics. main mineral phase samples calcite, several trace elements (i.e., up 0.48 wt.% Na2O, 0.73 MgO, 4.19 SO3, 0.16 SrO 2.21 Yb2O3) mineral-chemistry composition. dominant facies lamination shrubs, most common among thermogenic travertines area. Based stalactites, twenty-nine different were identified, belonging following orders: Synechococcales (28%), Oscillatoriales (27%), Chroococcales (21%) Nostocales (21%), Spirulinales (3%). Among them, thermophilic (Spirulina subtilissima) limestone substrate (Chroococcus lithophilus, Leptolyngbya perforans, ercegovicii) identified. identified found participate biomineralization processes. characteristic activity endolithic destroying calcite crystals outer layer. In few cases, calcified cyanobacterial sheaths detected. presence filamentous Cyanobacteria, along extracellular polymeric substance (EPS), creates dense net resulting retention calcium carbonate crystals.