The 3D structure of the Colli Albani volcano

In this paper we describe the structural architecture of the Colli Albani from the sedimentary cover to the upper mantle. The regional stratigraphy, deep wells and sedimentary xenoliths embedded in the pyroclastic deposits have been considered in order to constrain the composition and structure of the sedimentary substratum, whereas the lithospheric structure of the volcano has been investigated using seismic tomography and receiver function analyses. The main features at depth are a sub-horizontal Moho located at 20 – 24 km and a low velocity in the uppermost mantle. The Moho separates two anisotropic regions, one located in the uppermost mantle and a second in the lower crust. The anisotropic fabric can be interpreted as being due to a sub-vertical flux in the mantle coherent with the magma uprise from a mantle source. Seismolo- gical analyses do not discriminate velocity reductions ascribable to melt in the shallow crust. An intrusive body, which up-domed the limestone layer, is present beneath the central part of the volcano at depths greater than 5 km. These data are in agreement with the position of the magma chamber deduced by the presence of thermo-metamorphic xenoliths related to dolostone and limestone protolithes, which represent the lowermost portion of the Mesozoic – Cenozoic sedimentary sequence