Paleosols provide sedimentation, relative age, and climatic information about the alluvial fan of the River Tirso (Central-Western Sardinia, Italy)

Abstract

Four representative paleosols in the Plio-Pleistocene alluvial fan of the River Tirso (Central-Western Sardinia, Italy) were studied for paleoenvironmental information, to describe the sedimentology of the alluvial fan, and to define a relative chronological framework for the fan. The representative depositional units and associated paleosols were characterised by fieldwork, physical, chemical, and mineralogical analyses. Pedogenesis was mostly driven by the time and climate factors. In the proximal fan location, pedogenesis was initially influenced by a warm subtropical-tropical climate of the Late Pliocene and subsequently by warm and humid interglacial phases of the Pleistocene. These phases were also responsible for soil formation in the middle fan. In the distal reaches of the fan, pedogenesis was driven by the different climatic pulses of the Late Pleistocene Tyrrhenian interglacial (MIS 5). Pleistocene eustatic sea level changes directly influenced the lowest elevations of the middle fan and the distal fan. Erosion and soil truncation mainly occurred in the proximal fan and at the highest elevations of the middle fan during glacial phases.