EVOLUZIONE STRUTTURALE DELLE LIGURIDI ESTERNE TRA LA MEDIA VAL CENO E LA VAL D'ARDA (APPENNINO SETTENTRIONALE, PROVINCE DI PARMA E PIACENZA)

Abstract

The stratigraphic and structural analyses, carried out on the Extemal Ligurian Units of the Northern Apennines, al­lowed to draw a Geological-Structural Map (1 :25.000) of a 150kmq area cropping out between the Parma and Piacenza provinces and to reoonstruct the evolution of thls part of the chain. everal tectonic phases were recognized: - the first phase (late Santonian ?) was characterized by ex­tensional faults which split up the sedimentary successions resting on the apulian continental rise and stacked part of them on the ocean floor; - the second one (pre- middle/late Eocene), due to simple shearing in the accretionary wedge, was responsible both for the making of the main tectonc units and the nucleation of large overtumed and neutra! folds within them; - the third phase (post-Oligocene), due to pure shear connected to the continental collision, was responsible for the making of upright folds, thrusts and strike-slip faults that deeply modified the features due the the previous phase; - the last phase, only locally recongnized, was character­ized by extensional faults that reworked most of the previ­ous compressive faults.