The Western Mediterranean extensional basins and the Alpine orogen |
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Authors: | Carlo Doglioni Erwan Gueguen Francesc Sàbat & Manuel Fernandez |
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Institution: | Centro di Geodinamica, Universitàdella Basilicata, Via Anzio, 85100 Potenza, Italy,;Universitat de Barcelona, Departamento de Geologia Dinàmica, Geofìsica i Palaeontologia, zona de Pedralbes, 08028 Barcelona, Spain,;CSIC, Institute of Earth Sciences (Jaume Almera) 08028 Barcelona, Spain |
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Abstract: | The western Mediterranean late Oligocene–Miocene basins (Alboran, Valencia and Provençal basins) are a coherent system of interrelated troughs. In all basins normal faults and thermal subsidence migrated toward the east progressively moving to the Miocene-to-Pleistocene Algerian and Tyrrhenian basins. All those troughs appear elements of the back-arc opening related to the eastward roll-back of the W-directed Apennines–Maghrebides subduction zone, similarly to western Pacific back-arc settings. These late Oligocene–early Miocene basins nucleated both within the Betic cordillera (e.g. Alboran sea) and in its foreland (Valencia and Provençal troughs). The N40–70° direction of grabens is oblique to the coexisting N60–80°-trending orogen and shows its structural independence from the orogenic roots. Thus, as the extension cross-cuts the orogen and developed also well outside the thrust belt front, the westernmost basins of the Mediterranean had to develop independently from the Alps-Betics orogen. Therefore, the Alboran extension, considered a classic example of a basin generated by the collapse of an orogen, cannot be ascribed to the detachment or annihilation of the lithospheric root. In contrast with the eastward migrating extensional basins, the Betic-Balearic thrust front was migrating westward producing interference or inversion structures. |
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