Evidenze di tettonica recente nell'area Monte Campo dei Fiori - Lago di Varese

Abstract

Recent tectonic phenomena affect both the karst landforms and the Plio-Quaternary stratigraphic succession of the area around Mt. Campo dei Fiori - Lake of Varese (Lombardy): Karst landforms are dislocated by simple-shear movements, which took place at bed junctions. The age of these dislocations, obtained from U/Th radiometric dating on speleothems, is older than 350.000 years. Marine sediments of Early Pliocene age outcrop at 350 m a.s.l. on the slopes of the "Brinzio - Maroggia Anticline" and at 200 m a.s.L in the "Lake of Varese Syncline". Late Pliocene and early Pleistocene continental deposits (deltaic, lacustrine, ice contact and fluvial deposits) show evidence of brittle tectonic deformations (faults, fractures and subordinate folds) acting under a unitary field of stresses (subvertical g1, and subhorizontal NNW-NNE trending c3). After the Pliocene transgression, a general uplifting and growth of alpine folds are hypothesized. This event brought about the development of depressions in the syncline zone, marked by extensional phenomena recorded in Plio-Pleistocene continental deposits. There is no evidence of recent tectonics from 350,000 years B.P. onwards.