Il massiccio carbonatico della Bernadia nelle Prealpi Giulie (Friuli, Italia NE): la registrazione di eventi tettonici tra il Cretacico superiore e il Quaternario

Abstract

On the basis of geological mapping and mesostructural analysis, structural framework of the Bernadia carbonate massif (southern Julian Prealps) was pointed out. It deals with a tectonic building linked to the superposition between two tectonic systems: the Paleogene External Dinaric Chain and the Neogene-Quaternary Southalpine one. During Mesozoic Bernadia massif was part of the passive margin of Adria microplate. Starting from Late Cretaceous to Lower Eocene the study area was part of the WSW \u2013 verging Dinaric foredeep-foreland system. The Paleogene imbricate thrust-system shows staircase trajectory and duplex-geometries; thrusts are mainly NW-SE trending and present WSW tectonic transport; inherited Mesozoic normal faults (NNE-SSW and NW-SE-trending) are often inverted in lateral and frontal ramps respectively. Starting from Middle Miocene the S-SSE verging Neogene- Quaternary Southalpine Chain started, giving rise to a low-angle, approximately WSW-ENE to WNW-ESE trending thrust-system. Neoalpine compression originated deformation of the Paleogene structural belt: i.e. strong ondulations of the hinges of the Dinaric folds and production of culminations and depressions of the first folds (dome-basin pattern). Moreover the Neogene \u2013 Quaternary thrusts often re-utilised the low-angle Dinaric ramp as frontal or lateral ones