Volcaniclastic sedimentation in coastal environments: the interplay between volcanism and Quaternary sea level changes (central Italy)

Abstract

The geometry and facies characteristics of volcaniclastic and marine sequences have been investigated in relation to synvolcanic and intervolcanic episodes and to Quaternary sea level changes, in an area of relative recent tectonic stability. The studied area is a coastal sector of northern Latium, where the products of three different Quaternary volcanoes reached the coast, during a period ranging between 0.45 and 0.1 Ma. The onshore sedimentation area includes lowland situated between pre-existing structural and volcanic constructional highlands with no clearly defined structural basin margins, called the Tuscania basin. Detailed stratigraphic field work has allowed analysis of lateral facies relationships between marine and volcaniclastic sediments, using volcanic horizons, mainly geochronologically dated, pyroclastic flow deposits, and fallout deposits as stratigraphical markers. The successions have been organized in Unconformity Bounded Stratigraphic Units, and the Synthems are bounded by primary order unconformities recognized throughout the continental area down to the coast. The stratigraphies have been compared with the oxygen isotope scale of Pisias et al. (Marine Geol. 59 (1994) 217). The analysis of the components and of the lithofacies of each Synthem has proven to be a powerful tool to correlate marine and volcano-sedimentary successions in areas affected by the interaction between volcanic activity and sea level changes.