Testimonianza dell'"evento a gessi" nei depositi di avanfossa della Val Roveto (Appennino centrale): considerazioni sull'estensione spazio-temporale dell'avanfossa messiniana

In this paper some hypothesis about the time-space extension of the Messinian foredeep of the central Apennines are suggested. In particular, the structural setting of the portion of the Roveto Valley between Cappadocia and Petrella Liri is discussed, and some geochemical results from gypsum minerals collected in the flysch of the Roveto Valley are presented. The dimension (10-20 mm) and the attitude of these gypsum minerals (c-axes parallel to the strata surface) allow to suggest a diagenetic origin. Moreover, the 87Sr/86Sr values of these small gypsum crystals are the same of the Messinian evaporites of the Italian region (MÙLLER and MUELLER. 1991; AHARON et alii, 1993). So, we suggest for these diagenetically gypsum an origin from high salinity interstitial waters, relics of Messinian evaporated waters (Messinian salinity crisis). This hypothesis allow to extend up Lo the late Messinian the activity of the Salto-Tagliacozzo-Marsica foredeep. In this way, the clastic wedge of this foredeep basin would be coeval to the Laga basin siliciclastic deposits.