Sedimentary and pedological processes in the Upper Pleistocene loess of Northern Italy. The Bagaggera sequence.

The Bagaggera sequence consists of two Late Pleistocene loesses superimposed on the top of Middle Pleistocene fluviatile sediments. The lower loess includes at its base a Mousterian archaeological level represented by artifacts (dated by TL as 60,500 ± 7500 BP) and charcoal from hearths which mainly consists of boreal forest species. At the top of the lower loess, Aurignacian artifacts occur which suggest a tentative date of 35,000 BP. The sedimentary and pedological processes which lead to the formation of the sequence, were reconstructed by means of mineral and textural analyses and thin section analysis and can be summarized as follows: • - Erosion and colluviation of the Eemian soil at the base of the sequence during the Early Würm (Isotopic Substages 5 a-c). • - Sedimentation of the lower loess deposits during the first Pleniglacial period (Isotopic Stage 4). A large number of coarse pedofeatures in this soil suggests that primary aeolian dust has been redistributed in place or for short distances by syngenetic slight pedogenesis and by water reworking, as a result of alternating phases of wet and dry climate. • - An alfisol characterized by strong clay illuviation developed in the lower loess during the Hengelo-Arcy interstadial phase. Its top was affected by reworking and slight frost activity at the beginning of the second Pleniglacial period (Isotopic Stage 2). • - The upper loess was deposited in a drier environment during the second Pleniglacial period (Isotopic Stage 2). Water reworking was less effective. • - Holocene weathering is expressed by clay illuviation and slight hydromorphism.