Transtensional shear zones controlling volcanic eruptions: the iddle Pleistocene Mt Amiata volcano (inner Northern Apennines, Italy)

The Mt Amiata volcano is characterized by the SW–NE align- ment of the eruption centres, as well as other Italian Pleisto- cene volcanoes. We carried out a structural and kinematic analysis in a broad stripe comprehending the eruption centres and the substratum, towards NE and SW. The results point out that a transtensional left-lateral brittle shear zone affects the pre-Neogene substratum, the Middle Pleistocene volcanic rocks and the Late Pleistocene travertines. This transtensional struc- ture is active since the Early Pliocene. It controlled the location of the eruption centres through pull-apart structures, thus providing the deep structural channels for the uprising of magma to the surface. The Mt Amiata volcano represents a key study area to investigate the Pleistocene to Present relation- ships between tectonics and magmatism in the Tyrrhenian area