The crust-mantle boundary in the Ligurian area: geological and geodynamic implications

The configuration of the crust-mantle boundary in the transition zone between the Western Alps and the northern Apennines is examined. Some recent Moho contour maps are discussed from a geological standpoint, and their paleogeographic and geodynamic implications are considered. It is assumed that three principal Moho surfaces exist in the area. Most authors agree that two of them (the European and Adriatic Mohos) belong to the pre-collisional Europe and Adria continental plates, while the nature of the third ("Ligurian-Tuscan' Moho) is debated. On the basis of various arguments, the present work suggests that the Ligurian-Tuscan Moho should be considered as forming part of the Adria Moho. The deepest surface is the Europe Moho, which generally dips to the E under the Ligurian-Tuscan Moho. The Adria Moho dips to the W or to the SW under the Ligurian-Tuscan Moho, which is the shallowest crust boundary. The overlap of the Ligurian-Tuscan Moho on the Adriatic one is considered to be a major intracontinental imbrication, which is connected chronologically and dynamically to the Oligo-Miocene opening of the Ligurian-Balearic basin and to the subsequent Mio-Pliocene opening of the Tyrrhenian basin. -from Authors