Hidden paleosols on a high-elevation Alpine plateau (NW Italy) : Evidence for Lateglacial Nunatak?

Alpine soils can provide valuable paleo-environmental information, representing a powerful tool for paleoclimate reconstruction. However, since Pleistocene glaciations and erosion-related processes erased most of the pre-existing landforms and soils, reconstructing soil and landscape development in high-mountain areas can be a difficult task. In particular, a relevant lack of information exists on the transition between the Last Glacial Maximum (LGM ~21,000 yr BP) and the Holocene (~11,700 yr BP), with this climatic shift that plays a crucial role for environmental thresholds identification. The present study aims at reconstructing the history and origin of hidden paleosols inside periglacial blockstreams and blockfields on a high-elevation Alpine plateau (Stolenberg Plateau) above 3000 m a.s.l., in the Northwestern Italian Alps. The results indicate that these soils recorded the main warming climatic phases occurred from the end of the LGM until the Late Holocene ~4000 yr BP. Our reconstructions, together with the high carbon stocks of these paleosols, suggest that during warming phases the environmental conditions on the Plateau were suitable for plant life and pedogenesis, already since 22,000–21,000 yr BP. These paleosols reasonably evidence the existence of a Lateglacial Nunatak representing, to our knowledge, one of the first documented relict non-glacial surfaces in the high-elevated European Alps. Thus, the Stolenberg Plateau provides important information about past climate and surface processes since the end of LGM, suggesting new perspectives on the long-term landscape evolution of the high European Alps.