Estructura de los mantos superior e inferior del Pedraforca (Pirineos orientales).

• Autores: Albert Martínez i Rius, X. Berástegui, M. Losantos, Elmar Schöllhorn
• Localización: Geogaceta, ISSN 0213-683X, Nº. 30, 2001, págs. 182-186
• Idioma: español
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• Resumen

  • The Pedraforca nappe is one of the allochtonous structural units in which the Cover Upper thrust sheets of the southern Pyrenees are organised. Its is internally constituted by two thrust sheets, namely Upper Pedraforca thrust sheet and Lower Pedraforca thrust sheet. As a whole, they were emplaced in a piggyback thrusting sequence. But in the detail, a new, minor structural unit, here named "Intermediate unit", has been found in between them. This newly identified thrust sheet mainly consists of a carbonate breccia series, derived from the Lower Cretaceous sediments forming the Upper Pedraforca thrust sheet, showing an "inverted mountain" internal arrangement of elements. Restoration of a detailed cross-section allows us to interpret the Upper Pedraforca thrust sheet as the result of tectonic inversion of a Lower Cretaceous extensional basin occurred during late Cretaceous times. The sediments forming the Intermediate Unit are syntectonic materials, because they generated synchronously to the tectonic transportation of the Upper Pedraforca thrust sheet (Santonian to Maastrichtian). Further emplacement of the Intermediate unit included piggy back transportation of the Upper Pedraforca thrust sheet, until both structural units were definitively emplaced, and their frontal parts were covered by late Cretaceous to Palaeogene continental redbeds