Geological Map of the Western Rift of M. Etna (Italy)

Mt. Etna (3340 m a.s.l.) is the most active volcano in Europe, covering an area of 1250 km2, with more than 500 ka of geological history. In this work an accurate structural and geological field survey of the Western-Rift was performed at 1:10,000 scale, by using lithostratigraphic criteria and Unconformity-Bounded Units (UBU), in according to the guidelines suggested by International Subcommission on Stratigraphic Classification (ISSC) and the Italian Geological Survey (SGN). In order to improve the field-work data, an aerial photo interpretation was realized, by using high resolution ortho-photo and DEM elaboration, producing a mapping with high detail of the lava flows boundaries. During the field work activity the eruptive fissures configuration of the WR has been mapped, and lithostratigraphic units have been identified and organized in different ranks: formation, member and lava flow. The lithostratigraphic units allow to identify immediately during the field-survey the lithologic characteristics and stratigraphic relationships of rock bodies. To summarize and synthesise the main phases of the WR evolution, the lithostratigraphic units were grouped in different synthem units according to the stratigraphic framework of the volcano east flank, where the applied methodology has been defined and tested for the first time. The volcanic succession of the West-Rift is formed by the oldest subaerial lava flows of Etna region (Adrano Synthem) that are unconformably covered by the lava flow succession generated by old volcano activity (La Timpe Synthem) and by products of Ellittico Volcano (Concazze Synthem). The main portion of the study area is formed by the product related to the Mongibello volcano eruptive activity of the past 14 ka (Il Piano Synthem). The Mongibello lava succession is constituted by the superimposition of several lava flow fields generated by more than 50 eruptive fissures, forming the core of the West-Rift. The eruptive fissures strike about 260°, fed several monogenetic cones and are concentrated in a bounded zone 4 km-wide, located in the central portion of the western flank. Some of these eruptive fissures took place in the last 2 ka and are reported in historical chronicles. The result of this work is a detailed geological map at 1:20,000 scale of the WR, which points out the geological and structural setting of the area and significantly improve the knowledge of its evolution in order to better assess the whole eruptive history of Mt. Etna as well as its structural framework.