Various morphological types of thermogenic travertines in Northern Euboea and Eastern Central Greece

Résumé

In the northern part of Euboea Island and the neighbouring part of the mainland in eastern central Greece, many hot springs exist and some of them create travertine deposits. The objectives of the study were to identify and describe the various morphological types of the thermogenic travertine deposits. The samples were studied at the lab with optical microscopy, X-Ray Diffraction, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), in order to verify their main mineralogical composition and their mineral chemistry. The studied travertine deposits consist mainly of aragonite and calcite, but in some cases, as main mineral phase, an amorphous hydrous ferric oxyhydroxide (ferrihydrite), was also identified. The morphological types that were identified were of great variety (mounds, travertine caves etc) and some of them were quite rare (cascades, remora etc). Morphological data and field observations suggest possible inorganic and organic controls on carbonate precipitation. Similar morphological types have been recorded at large travertine systems like Mammoth hot springs, Yellowstone National Park in USA and at Rapolano Terme, Italy.