DATAZIONE AL K/Ar DI PIROCLASTITI COME CONTRIBUTO ALLA CONOSCENZA DELL'EVOLUZIONE GEOMORFOLOGICA DELLA DEPRESSIONE TETTONICA DI NORCIA (APPENNINO CENTRALE, ITALIA)

Abstract

A K/ Ar datation has been obtained on sanidine cristals contained inside pyroclastic materials discovered in the up­per part of a fan deposits at Nottoria, Norcia basin. This deposit is weathered by a fersiallitic paleosol which suggest that its deposition occurred in a period previous to an Inter­glacial. The radiometric age of 0,23 9 0,03 establishs a first chronological setting of the depositional events in the tectonic depression. Another datation obtained on similar materials at Colmotino, in the nearby Cascia basin, gave an age of 0,29 9 00,3 my. These datations testify depositional events cor­risponding to the stage 8 in the chronology established on the deep-see sediments.