Note alla carta geologica del settore meridionale del vulcano di Monte Amiata

In the framework of the research project on the Monte Amiata volcano funded by the Regione Toscana, a detailed geological map of the southern sector of the volcano was produced as a test for applying stratigraphic and volcano-geology methodologies to geological mapping of a quaternary volcanic area. The geological field analysis involved all aspects of the volcanic rocks of Monte Amiata: lithological, petrographic, structural, geometric and morphological. The pre-volcanic sedimentary substrate includes the Ophiolitic Unit and the Santa Fiora Unit of the Ligurian Domain. For the cartography of volcanic units, the lithostratigraphic units (Formations) were grouped into UBSU units (Synthem and Subsynthem). Eleven Formations, included in two Synthems and five Subsynthemes, have been described and formally defined. The proposed geological map differs from the previous ones, which were characterized by only two omni-comprehensive great units, for the extreme detail in the survey, in the unit description and in the petrographic characterization. The stratigraphic framework reconstructed in this work, thanks to the accurate geological field survey, has made it possible to accurately define the nature of the various volcanic bodies (lava flow, lava dome, coulée), according to their lithological and outcrop characteristics, and to place them in their proper position within the geologic evolution of the volcano. Finally, despite the apparent homogeneity of mineralogical and chemical composition of Monte Amiata vulcanics, invoked in the previous literature as an obstacle to a clear geological and volcanological interpretation of the volcano, we have shown that each identified and mapped stratigraphic unit has petrographic peculiarities that allow differentiation and recognition it, as well as a set of distinguishable lithological and depositional characters.