Potential dust sources for loess deposits in Central Italy: A geochemical case study from the Loess-Paleosol-Sequence of Ponte Crispiero (Marche)

Identifying potential dust sources of Loess-Paleosol-Sequences (LPS) is important to understand past climatic and environmental conditions. For loess deposits of Central Italy different hypothesis on particle sources have been proposed, but none of them has been tested using a comprehensive geochemical approach yet.Here we present geochemical, mineralogical and grain-size data from selected deposits of a LPS situated at Ponte Crispiero (Marche, Central Italy) to obtain first insights on the provenance of particles deposited here.Loess deposits within the Ponte Crispiero succession are rather coarse (mostly coarse silt and fine sand) indicating a dominance of proximal dust sources. Applied geochemical indices suggest the alluvial plains of the Po River (Northern Italy) and its discharging area as major particle sources.According to these findings, the so-called Great Po Plain hypothesis, that claims the presence of a vast al-luvial landscape related to the sea-level drop of the Adriatic Sea during the Pleniglacial (i.e. Marine Isotope Stage MIS 4-2), may be considered as a realistic scenario. Such a considerable alluvial plain would have the potential as major source for silt and sand particles not only for the Ponte Crispiero LPS, but also for the loess on the Adriatic side of Central Italy. The main geochemical characteristics of Ponte Crispiero loess are the low con-centrations of Zr and Hf and the high contents of carbonate and transition elements compared to the Upper Continental Crust and other European loess sections. Overall, this study contributes towards a better under-standing of the provenance and origin of Italian loess. However, for further testing the Great Po Plain hy-pothesis, more (geochemical) investigations need to be conducted, especially in the surrounding areas of the Po plain.

Automated summary

By analyzing geochemical, mineralogical, and grain-size data from the loess profile in Ponte Crispiero, Central Italy, it has been found that the nearby Po River basin is the major source of the dust particles, supporting the authenticity of the Great Po Plain hypothesis.