Late Pleistocene-Holocene tephra and volcanic soils in the Vesuvius foothill, southern Italy: reconstruction of time spans of soil formation and climatic changes

In this work we present the main results of a multidisciplinary study of late Pleistocene to mid-Holocene primary tephra and interlayered volcanic soils as indicators of terrestrial ecosystem responses to late Quaternary climatic changes. We focused on a pedostratigraphic succession of soils developed on and/or buried by well-known volcanic layers of different ages, sourced from the Somma-Vesuvius volcano (Campania region, southern Italy). Five tephra give detailed chronological constraints to the stratigraphic record: the Pomici di Base tephron at the bottom (22 ka BP), followed upward by the Pomici Verdoline (19 ka BP), the Agnano Pomici Principali (APP) (12.26 ka BP), the Mercato (8.9 ka BP) and Avellino eruption (3.9 ka BP) pumice deposits at the top. Four pedons interlayered between each subsequent couple of tephra were studied in detail in terms of physical, chemical, mineralogical and micromorphological features, with special emphasis on (i) reconstructing dominant pedogenetic processes and corresponding (paleo)environmental/climatic conditions, along with (iii) degree of soil development and associated time spans. SEM-EDS analyses performed on two further tephra identified within two of above pedons but up to now unknown in the Vesuvius stratigraphy (referred to the Soccavo 4-5 and the Tufi Biancastri eruptions from the near Phlegrean Fields) permitted to fix further age constrains for more detailed assessment of rates of soil formation. Major climatic phases coherent with Last Glacial Maximum to Lateglacial and early- mid-Holocene climatic optimum are evidenced by varying degree of expression of andic properties, soil microstructure, carbonate accumulation, iron-oxide staining and silt-clay illuviation.