Late Quaternary evolution of the classical karst region and the gulf of Trieste (Italy)

The Gulf of Trieste (GOT) is an epicontinental semi-enclosed shallow marine basin in the NE Adriatic Sea, with a maximum depth of 25 m. The eastern side of the GOT is bordered by carbonate and turbiditic rocks of Upper Cretaceous and Paleogene age, belonging to the so-called Classical Karst Region (Kras-Carso) that extends across the border between SW Slovenia and NE Italy (Jurkovsek et al., 2016). From a geological point of view it lies in the northwestern part of the External Dinarides. Quaternary deposits and the reconstruction of the evolution of the area have been recently studied, in particular along the coastal sector. On the contrary, inland deposits, related to dolines, caves and fluviokarst valleys were almost neglected (Furlani et al., 2016). The study of such deposits can provide important contributions regarding the Quaternary evolution of the NW Dinaric area. In the last decade, the tectonic behavior of the Gulf of Trieste and surroundings has been studied using geomorphological, sedimentological and archaeological data (see Melis et al., 2012, Biolchi et al., 2016 and references therein). In particular, concerning sedimentological data, Quaternary marine sediments have been found and studied in the central part of the Gulf (submerged boreholes and beachrocks) and in the city of Trieste, thanks to archaeological excavations. Concerning the continental deposits, Frisia et al. (2005) studied a speleothem in the Gualtiero Savi cave in order to reconstruct the Holocene climate change, while Finocchiaro et al. (2015) and Furlani et al. (2016) described the sedimentological features of the stratigraphic sequence of the terrace outcropping in the Rosandra Valley (SE part of the Gulf), dating tentatively it back from the Eemian (MIS5e) to MIS2 (Fig. 1a). It represents the only exposed Quaternary sequence in the Italian sector of the Classical Karst Region. Quaternary deposits inside the nearby the Grotta degli Orsi cave were studied by Berto & Rubinato (2013), who reported the presence of Ursus Spelaeus on the floor surface and the walls. In the coastal sector, Biolchi et al. (2016) dated back a Gastropod included in a scree deposit to the late Pleistocene (Fig. 1b) (~35 years BP). Published and new data on geomorphological, sedimentological markers together with archeological remains and geophysical data are discussed in order to provide a new complete overview of the evolution of both inland and coasts.