The polyphase structure of the Tuscan Nappe is confirmed in two sectors, to the SE (Mt. Prana-Pescaglia) and NW (Castelpoggio-Carrara) of the Alpi Apuane Metamorphic Complex. The first deformational event produced a schistosity during an anchizonal thermobarometric regime. This schistosity is well developed within the argillitic lithologies and exhibits angular relationships to bedding everywhere indicating "northeastward vergences. The second deformational episode is marked by gently dipping tectonic contacts that follow the less competent horizons or the previous overthrusts. These contacts are associated with southwestward verging folds, that range up to one kilometer in size. The structures produced during these tectonic events are crosscut by a NW-SE trending fault system. According to the authors, the first, northeastward verging phase is attributable to the continental collision and the stacking of the tectonic units of the Apennines ("syn-nappe" phase). The later structures resulted from post-collisional, extensional tectonics ("post-nappe" phase) which led to the uplift and denudation of the Apuan Metamorphic Complex. The folds verging towards the Tyrrhenian Sea, which are often cited as a proof that the Tuscan Nappe was the result of tectonic movements from NE towards SW, developed after the stacking of nappes along a major shear zone situated between the stratigraphic base of the "Macigno" and the underlying Metamorphic Complex.

You do not currently have access to this article.