Magnetostratigraphic dating of an intensification of glacial activity in the southern Italian Alps during Marine Isotope Stage 22

摘要: Abstract We applied magnetostratigraphy and mammal biostratigraphy to date climate-sensitive pollen cycles lithostratigraphic units of the Pliocene–Pleistocene Leffe sedimentary succession from Southern Alps, Italy. The section was correlated additional sections (Casnigo, Fornaci di Ranica, Pianengo) construct a stratigraphic network along common fluviatile system (the Serio River) sourced in Alps flowing southward into Po River Basin. obtained coherent scenario climate variability for last ∼ 2 Myr. At Leffe, lacustrine deposition commenced during Olduvai Normal Subchron (1.94–1.78 Ma) lasted up chronologic level compatible with Marine Isotope Stage (MIS) 22 (0.87 Ma). Pollen analysis revealed that varied cyclically warm-temperate cool this time interval, but never as cold glacial intervals. around MIS 22, cooled globally. Gravels, attributed high-energy braided river systems fed locally by alluvial fans, prograded catchment area over Basin toward Plain response generalized event vegetation withdrawal enhanced physical erosion. time, Alpine valley glaciers reached their first maximum expansion glacier fronts located at only ∼ 5 km upstream Leffe.