GNGTS 2019 - Atti del 38° Convegno Nazionale

164 GNGTS 2019 S essione 1.2 spectacular rhythmicity is linked to the climatic variations induced by astronomical cycles (http:// www.isprambiente.gov.it/files/pubblicazioni/periodicitecnici/quaderni-sgi/quaderno7fasc6/ quad-7-vi-marne-a-fucoidi.pdf). The thickness is few tens of meters, so that generally only one strong reflector marks their presence in the pelagic domain. Conclusion. The MSC layer in the Adriatic Sea is generally constituted by the Gessosso Solfifera Formation, that means a mainly gypsum lithology. This layer is often laterally substituted by a hiatus corresponding to an erosional truncation (Marginal Erosion Surface, MES). Where present, the MSC layer has been calibrated by wells. Seismic profiles generally show one single reflector or a thin package of high amplitude reflectors. This makes often hard to distinguish not only the thickness of the gypsum layer but, where the layer is thin, it is not always simple to recognize if this is due to erosion or not deposition. During the Messinian, the diapirs related to the deep Burano Formation produced relative high and low structures that drove the sea bottom deposition and erosion. The MSC evaporite thickness seems to be mainly dependent from these halokinetic tectonic structures. Conversely, not direct regional correlation seems to exist between the MSC thickness and the Apennine Chain: this suggests that during the Messinian time the current Central Adriatic Sea was not jet involved in the westward tilting that affected this sector of the Adriatic foreland only during the Lower Pliocene. Reference Duggen S., Hoernie K., Van Den Bogaard P., Rupke L., Morgan J.P.; 2003: Deep roots of the Messinian salinity crisis. Nature , 422, 602-606. Geletti R., Del Ben A., Busetti M., Ramella R. and Volpi V.; 2008: Gas seeps linked to salt structures in the Central Adriatic Sea. Basin Research, 20, 473-487. Krijgsman W. et al. , 1999: LateNeogene evolution of the Taza-Guercif Basin (Rifean Corridor; Morocco) and implications for the Messinian salinity crisis. Mar. Geol., 153, 147±160. Lofi, J. (2018). Seismic Atlas of the Messinian salinity crisis markers in the Mediterranean Sea. Vollume 2 - Mémoires de la Société géologique de France, n.s., 2018, t. 181, and Commission for the Geological Map of the World, 72 p. + DVD. https ://doi. org/10.10682/ 2018M ESSINV2. Patacca E., Scandone P., Di Luzio E., Cavinato G.P. and Parotto M.; 2008: Structural architecture of the central Apennines: Interpretation of the CROP 11 seismic profile from the Adriatic coast to the orographic divide. Tectonics, 27, TC3006, doi:10.1029/2005TC001917. Fig. 3 - The NE-SW profile, produced on the base of the boreholes, depicting the position in depth of the top and base of the MSC gypsum. The profile, orthogonal to the Italian shoreline, is sited in coincidence with the B-418 seismic line (position in Fig. 1). As we can see, no clear relationship between depth and thickness can be recognized. The deepening of the two MSC horizons is related to the Apennine foredeep. There are not relationships between the reached depth and the MSC thickness, on the contrary, we can see a larger thickness on the higher sector. This observation suggests us that tilting of this foreland sector started after the MSC.