Tectonic control on laccolith emplacement in the northern Apennines fold-thrust belt: the Gavorrano intrusion (southern Tuscany, Italy)

Mechanical discontinuities within the crust, represented by tectonic structures (faults) or lithologic heterogeneities, strongly control the emplacement of magma as tabular intrusion within middle-upper crust. The occurrence of mechanical layering is common feature in fold and thrust belts. In the northern Apennine, a Cenozoic fold-thrust belt affected in its inner part by Neogene magmatism, the Gavorrano laccolith (southern Tuscany) is a particularly suitable example for studying the relationships between magmatism and tectonic structures. New geological mapping, together with a large amount of subsurface data available from historical mining activity in the area, have allowed the reconstruction of: 1 the original relationships of the intrusion within the nappe pile, and 2 the laccolith shape of intrusion. Using the Gavorrano laccolith as an example, propose that the emplacement of Neogene intrusiosns in southern Tuscany, was strongly controlled by the occurrence of mechanical discontinuities represented by thrust zones in the nappe pile