Multiproxy investigation of a Holocene sedimentary sequence near Ferrara (Italy): clues on the physiographic evolution of the eastern Padanian Plain.

Purpose: This paper investigates soils and sediments from the eastern Padanian Plain (northern Italy) in order to delineate the physiographic evolution of the area. Materials and methods: We present new geochemical, mineralogical and textural analyses of alluvial sediments collected from a 13-m-deep section located a few kilometres south of Ferrara. The chronology of the related depositional events is provided from C dating of tree trunks buried at depths of ca. 9 m and organic matter from the underlying horizons. Results and discussion: The data indicate that (1) the upper part of the sequence (down to depths of 9 m) includes sediments characterized by low nickel-chromium (Ni-Cr) concentrations ascribed to the alluvial deposits of the river Reno, deposited in the last 400 years; (2) buried soils (depths of 9-10.5 m) developed on Ni-Cr-rich sediments related to the river Po; and (3) the deeper facies (depths of 10.5-13 m) are CaCO-free and characterized by higher amounts of organic carbon, sulphur and arsenic, reflecting episodic lacustrine/marsh environments. These wetlands probably developed in the area during the Iron and Roman ages, persisting up to the Middle Ages. Conclusions: The data provide a contribution to the understanding of the evolution of the river network during the last 3,000 years and provide insights on the related paleohydrological framework that can be useful for geographical and historical reconstructions of the area. Results highlight the importance of investigating alluvial sediments to elucidate (1) fluctuations of environmental conditions and (2) anthropogenic impacts on the natural landscape. [ABSTRACT FROM AUTHOR]