Late Quaternary fluvial terraces of the Romagna and Marche Apennines, Italy: Climatic, lithologic, and tectonic controls on terrace genesis in an active orogen

We synthesize a new fluvial terrace chronostratigraphy of the Bidente and Musone Rivers cast within a broader European framework, which forms the basis of a terrace genesis and river incision model for the northern Apennines, Italy. Our model, supported by terrace long profiles, correlation to Po foreland sediments, 15 new radiocarbon dates, and published numeric and relative stratigraphic ages, highlights how drainage basin substrate drives concurrent formation of strath terraces in the Bidente basin and fill terraces in the Musone basin. Quaternary climate change paces the formative geomorphic processes through unsteady discharges of water and sediment. In the weathering-limited setting represented by the Bidente basin, siliciclastic detritus carves broad strath surfaces during glacial climates that are preserved as terraces as the river incises during the transition to an interglacial climate. In contrast, the transport-limited and carbonate detritus dominated Musone basin sees valleys deeply buried by aggradation during glacial climates followed by river incision during the transition to an interglacial climate. Incision of these rivers over the past similar to 1 million years has been both unsteady and non-uniform. These and all Po-Adriatic draining rivers are proximal to a base level defined by mean sea level and have little room for increasing their longitudinal profile concavities through incision, particularly in their lower reaches despite periodic glacio-eustatic drawdowns. As a result, the observed incision is best explained by rock uplift associated with active local fault or fold growth embedded in the actively thickening and uplifting Apennine foreland. (C) 2008 Elsevier Ltd. All rights reserved.