GNGTS 2013 - Atti del 32° Convegno Nazionale

Harpha Sea d.o.o. of Koper, acquired 132 km of multichannel seismic and 150 km of Chirp data (Fig. 1). All geophysical surveys were conducted with the R/V OGS Explora. Major lithologic units in the subsurface were identified on seismic reflection profiles by Busetti et al. (2010a, b). Additional subsurface data were provided from the Grado-1 well, drilled in 2008 for geothermal surveys on the northern coast of the Gulf (Della Vedova et al. , 2008; Cimolino et al. , 2010). The Grado-1 well recovered Upper Cretaceous platform carbonates from the well-bottom depth of 1108 up to 1007 m, and Paleogene carbonates from 1001 to 616,5 m. Those two units correspond to similar rocks outcropping in the Karst and Istria. Salty hot water at 42°C occur in two major fracture zones, encountered at 736-740 m, and from 1040 to the well bottom. Carbonates are followed by about 300 m of terrigenous sediment, interpreted to comprise 50-60 m of Eocene Flysch, followed by about 250 m of Miocene Molassa. The topmost sedimentary unit consists of Plio-Quaternary sediments with less than 300 m of thickness (Della Vedova et al. , 2008; Cimolino et al. , 2010). Results and discussion. The main seismo-stratigraphic units and horizons interpreted from the multi-channel seismic profiles (MCS) are the Carnian Unconformity, the Meso-Cenozoic carbonates (Friuli Carbonate Platform in the east, and Scaglia in the west in Belluno basinal area), the Eocene turbidites of the Flysch, the Eocene Gallare Marls, the Pliocene progradation sequence and the Quaternary sediments of continental and marine origin (Busetti et al. , 2010a, b). The Carnian Unconformity was encountered in the Amanda well (drilled offshore westward the study area) at 5340 m, and marks the base of the Late Triassic Dolomia Principale. The Carnian Unconformity is a well-known horizon in the seismic exploration data of the Friuli Plain, where it is considered to be one of the detachment levels of the thrusts (Poli and Fig. 1 – Position map of the multichannel seismic and high resolution Chirp data collected by N/R OGS Explora in 2005 (blu lines), in 2009 (light blue lines), and in 2013 (orange lines), for a total of 656 km. Dashed red lines are the offshore national borders. 30 GNGTS 2013 S essione 3.1