LEFT LATERAL TRANSPRESSIVE DUPLEX AT PASSO DURAN, BELLUNO DOLOMITES (EASTERN SOUTHERN ALPS, NORTHERN ITALY)

During geological survey for the CARG project (Italian Geological Map, Foglio 046 “Longarone” ) we focused our attention on an interesting left lateral transpressive zone along the Valsugana Line which is the main Neogene Thrust of the Eastern Southern Alps. This transfer zone is located between Forno di Zoldo and Agordo, forming a rhombohedric structure (Cime di S. Sebastiano Megalithon) bordered to the north and south by WSW-ENE trending thrusts (Val di Zoldo and Moschesin Thrusts) and to the west and east by two SSW-NNE trending left lateral faults: the Passo Duran Line and the Cima di Pramper Line (Bianchin & Semenza, 1965). This fault system produces several duplexes and tectonic slices deforming the Triassic succession (Gianolla et al., 1988). The study area is very complex from the litostratigraphic and tectonic point of view, mainly because of: - the presence of inherited Permo-Triassic and Giurassic extensional structures reactivated and inverted during the Alpine compressions; - the occurrence along the Passo Duran Line of an anomalous and monotonous, mainly terrigenous Ladinian-Carnian succession; - a polyphase Alpine deformation. Three tectonic Neoalpine pulses we recognized: Dinaric trend from NE (Late Oligocene-Early Miocene), Valsugana trend from NNW (Middle-Late Miocene) and Adriatic trend from ESE (Pliocene-Pleistocene). The last event is widely represented in this fault system, especially by strike-slip faults. Bibliografia Bianchin G. & Semenza E., 1965 - Ann. Univ. Ferrara, sez. 9, 1, 2, pp. 27-57. Gianolla P., Prosser G., Siorpaes C., 1988 - Rend. S.G.I., 11, 2, 217-220.