Characteristics and genesis of volcanic soils from South Central Italy: Mt Gauro (Phlegraean Fields, Campania) and Vico lake (Latium)

South Central Italy (Latium and Campania regions) is an interesting geographic area to study soil development in volcanic materials because of: (a) the presence of volcanoes active during late Pleistocene and Holocene; (b) the occurrence of several pyroclastic deposits of known ages, and c) the Mediterranean climate (mesic and ustic/xeric pedoclimate). This district, often called “Campano-Laziale”, is geographically divided into the Roman and Campanian petrographic provinces (Figure 1), and is characterized by extensive volcanic deposits with a wide variety in composition of lava and volcanic tephra ranging from alkali-trachytic to latitic (Scandone et al. 1991, Di Vito et al. 1999, De Vivo et al. 2001). Many of the volcanoes in Central Italy are stratovolcanoes formed by alkali-potassic magmatic lava, characteristic of the Campano-Roman petrographic Province. The activity dates back 1300 ka (Sollevanti 1983, Bidini et al. 1984, Barbieri et al. 1988). Two areas have been investigated: an old volcano, the Vico Caldera in the Latium district and a young volcano in the Phlegraean Fields, Campania. Eruptions have been characterized by a variety of explosive event sequences and magnitudes in the past 1500–2000 ka. The Vico volcano consists of lavas of various composition, including leucitites, leucite– tephrites or leucite–phonolites in the first cycle and trachy-andesitic or latitic products in the second cycle (Lulli and Bidini 1978, Lulli et al. 1988, Scandone et al. 1991). The actual body of the Vico volcano is a lake of 7–8 km in diameter that occupies an area of 150 km2 but the surroundings covered by Vico’s pyroclastics are much larger. The Monte Gauro volcano is formed during the last period of activity (10 ka) of the Phlegraean Fields and is therefore considered as very young. The purpose of this study is to investigate the genesis and the properties of four pedons, formed in different tephra-derived materials inside the main caldera of Gauro and Vico volcanoes, to investigate the influence of the parent material and time on pedogenic processes under a Mediterranean climate.