Pluton emplacement in the Northern Tyrrhenian area, Italy
F. Rossetti, C. Faccenna, V. Acocella, R. Funiciello, L. Jolivet, F. Salvini, 1999. "Pluton emplacement in the Northern Tyrrhenian area, Italy", Salt, Shale and Igneous Diapirs in and around Europe, Bruno C. Vendeville, Yossi Mart, Jean-Louis Vigneresse
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The post-orogenic extensional processes that affected the inner sector of the Northern Apennine orogenic wedge (i.e. the Northern Tyrrhenian region) were accompanied by the emplacement of chiefly anatectic intrusive rocks of Late Miocene to Mid-Pleistocene age. In this paper, we compare geological and structural data from Messinian-Pliocene monzogranitic intrusions located both offshore (Monte Capanne, Porto Azzurro, Montecristo and Giglio) and onshore (Gavorrano and Botro ai Marmi) in the Northern Tyrrhenian region to constrain modes of pluton emplacement. Offshore, eastward non-coaxial extensional shear zones active both in ductile and brittle conditions accompanied the emplacement of the monzogranitic intrusions, and accommodated extension oriented E-W to WNW-ESE. Onshore, N-S dextral strike-slip faulting was active both during and after the late stage of emplacement of both Botro ai Marmi and Gavorrano plutons, and controlled their rise in coincidence with releasing bends. In our interpretation, the N-S, Late Miocene-Pliocene strike-slip faulting constitutes a secondary shear feature in a context of generalized post-orogenic extension, accommodating in the brittle upper crust the non-coaxial ductile extension in the lower crust. In this framework, N-S strike-slip faults localized the rise of early anatectic magma, generated during regional post-orogenic extension and residing at the base of the extending crust.