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Oblique Convergence Zones |
Centro di Geodinamica, Università della Basilicata, Via Anzio, I-85100 Potenza, Italy schiattarella{at}unibas.it
The Pollino Ridge is a N120° trending morpho-structure, formed by Meso-Cenozoic carbonate rocks, that marks the boundary between Calabria and Lucania (southern Italy). It is bordered by Quaternary basins filled by both marine and continental sediments. A detailed geological survey and structural analysis in an area elongated perpendicular to the axis of the chain, ranging from the Morano Calabro basin to Mount Madonna del Pollino, was carried out. Data show that the entire mountain ridge and nearby Quaternary basins experienced several deformations in recent times, after the Mio-Pliocene thrust tectonics. Moreover, data are also consistent with numerous observations along the Calabria-Lucania boundary, from the Lauria Mountains to the Castrovillari basin. The present structure derives from reorganization of the pre-existing tectonogenetic configuration by Plio-Quaternary brittle tectonics. Mapping and kinematic analysis of a thrust along the northern (Lucanian) side of the Pollino Chain was performed for the first time. This thrust brings both the Cretaceous platform limestones and the Cerchiara Formation (lower Miocene age) over the Bifurto Formation (middle Miocene age). Low-angle transtensional faults along the southern (Calabrian) side were also mapped and analysed. These faults have created ‘younger-on-older’ type tectonic contacts. The present structure of the ridge is due to the effects of two different Quaternary tectonic stages. The first, lower Pleistocene in age, was characterized by strike-slip tectonics. It truncated ramp folds, producing new contractional and extensional features on the opposite sides of the carbonate ridge. The second stage occurred during middle Pleistocene times and was a purely extensional regime with a counter-Apenninic tensional axis, which reactivated the pre-existing structural pattern with different kinematics. However, both tectonic stages should be interpreted as a consequence of the continuous reorganization of the local stress fields as a result of a rotational field acting along the Pollino shear zone. The best explanation of this phenomenon seems to be a counter-clockwise block rotation of the carbonate ridge in an unchanging regional stress field.
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  M. Tropeano, L. Sabato, and P. Pieri Filling and cannibalization of a foredeep: the Bradanic Trough, Southern Italy Geological Society, London, Special Publications, 2002; 191: 55 - 79. [Abstract] [PDF]
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