GNGTS 2013 - Atti del 32° Convegno Nazionale

faults, that cut the previous Dinaric thrusts, involving the Mesozoic carbonates, which produced a series of positive flower structures and related structural highs. Neotectonic activity of the flower structures is indicated by fault strands which displace the Messinian-Pliocene erosional surface at the top of the Flysch with several meters of throw. As suggested by Busetti et al. (2010a, b) these structures are the northwestward continuation of the Hrastovlje Thrust that deforms the outcropping Flysch in the Istria Peninsula in the foreland of the Dinaric Frontal Ramp (Placer et al. , 2010). The newly acquired MCS dataset clearly shows that the structures outcropping along the southeastern coast of the Gulf of Trieste continue westward into the offshore area. For example, one of the most prominent structures is a several kilometers wide anticline in the carbonates, that corresponds to the Izola anticline, a small isolated limestone outcrop along the coast entirely surrounded by the Flysch (Fig. 3). Our seismic profiles show that the axis of the anticline continues into the gulf in the NW-SE direction and plunges moderately towards the NW. The conformably overlying Flysch layers on the top of the carbonates are affected by folding, and the anticline is covered by sub-horizontal Quaternary sediments, which demonstrates that the onset of folding postdates the deposition of the Flysch, and that the deformation terminated by the Quaternary. Post-thrusting transpressional reactivation affected both the Mesozoic extensional faults at the paleoshelf margin and slope system of the carbonate platform, and the faults controlling the Paleogene intraplatform carbonate basins, as well as the Cenozoic thrusts and folds. These faults are subvertical and displace the Carnian Unconformity, and are associated with transpressional flower structures that deform the carbonates and the Eocene Flysch. Additionally, the fault strands clearly vertically offset the Pliocene Unconformity for several meters to several tens of meters. Weak deformation of the overlying marine and continental Quaternary sediments can also be inferred. We attribute this transpressional activity to the ongoing northward movement Fig. 3 – Brute stack of the multichannel seismic profiles acquired along the Istrian coasts, across the Izola Anticline. Inset map with onshore location of the Izola Anticline and the seismic profiles (red line). 32 GNGTS 2013 S essione 3.1