SEDIMENT PRODUCTION AND EROSIVE RATES OF CALABRIA FROM HIGHWATER TO DEEP‐MARINE ENVIRONMENTS

There are several processes controlling sediment generation from different bedrock lithotypes weathering, through transport and intermittent storage, to eventual long‐term deposition in a marine sedimentary basin. These processes impart textural and compositional signals on the final sedimentary deposit. Integrating sediment generation and Earth surface process models, viewed in terms of sediment routing systems, can be parameterized under different conditions of climate and tectonics. Above all, the evolution of sediment involves important modifications to the original parent rock such as chemical and mechanical weathering of bedrock and regolith, and the fractionation, reworking and mixing of grains during transport up to a final depositional site. Different source area lithotypes have a range of capacities for generating sediment by chemical alteration and physical disaggregation, and different bedrock types have different capacities for breaking down into grain‐size ranges. Analyzing the composition of river and coastal clastic sediment, in relation to the surface exposure of multiple or simple lithologies of drained catchments, it is possible to observe if each type of rocks in source areas are under‐represented (diluted) or over‐represented (concentrated) in both river and marine sediment compared to their outcropping surface area. Analyses of metamorphic and granitic terrains show that the sediment generation index (SGI) of granitoid rocks is 14–20 times the SGI of slates and schists, and the SGI of gneisses is five times that of slates and schists. In sedimentary terrains the sediment generation index is very high for siliciclastic source rocks and lower for carbonate (both limestones and dolostones) with siliciclastic sources 3–20 times more efficient at producing sand‐grade sediment than carbonates, partially delivered to the world oceans by rivers as solutes. The expected amount of sediment generation index of volcanic effusive felsic to intermediate rocks is higher for lavas with respect to pyroclastic rocks. Specifically, the sediment generation index of lavas is 0.9–12.3 times higher than that of pyroclastic rocks, even if these latter constitute a minor outcrop area of the source terrains. Thus, there is a divergence between the bulk composition and texture of a parent bedrock and the composition of the sediment grain assemblages in river and marine facies bedload. This divergence increases over time as the sediment is dispersed in the context of the geological sediment routing system. Using these concepts, we will be better able to establish what meaningful information about the geological forces shaping mountainous fronts can be interpreted from its sediment mass fluxes and management