Glacio-eustatic forcing on Middle Pleistocene fluvial-lacustrine depositional processes: a case history from the Tyrrhenian Sea margin of central Italy

The complex stratigraphic setting of alternating volcanic and fluvial-lacustrine sedimentary deposits in the surroundings of Castel Cellesi village (Latium region, central Italy) offers an unprecedented opportunity to examine the influence of glacio-eustatic forcing on the depositional processes during Pleistocene times in the upper catchment of the Tiber River, in the inland sector of the Tyrrhenian Sea margin of Italy. Tight geochronologic constraints on the timing of sediment deposition have been established through precise Ar-40/Ar-39 dating of intervening volcanic layers. These new age constraints reveal a clear chronological correlation between sediment aggradation phases and sea-level rises, as evidenced by the delta O-18 record and relative sea-level (RSL) curve. The analysis of pyroclastic-flow deposits within incised paleo-valleys further indicates a relationship between periods of erosion or non-deposition and sea-level lowstands. Specifically, twelve Ar-40/Ar-39 dates have delineated three successive aggradational fluvial-lacustrine successions deposited during the sea-level rises of Marine Isotope Stages (MIS) 13, 11, and 9, as well as the erosional features associated with the sea-level drops of MIS 12 and 10.