Environmental changes in East-Central Europe from a Middle to Late Holocene Romanian cave sediment record

Abstract

Caves are sensitive to hydrological processes including sediment transport associated with changes in external climatic conditions. When located in the proximity of prehistoric settlements, cave sediments can provide details about human activities and help to elucidate the paleoenvironment. Here, we present a comprehensive analysis of lithological, geochemical, magnetic, organic matter, non-pollen palynomorphs, and charcoal data from sediment in Ciur Izbuc Cave, revealing significant paleoenvironmental and hydrodynamic changes over the past 6500 years. The first phase (6500–3500 calibrated years BP; cal BP) depicts a dynamic system with constant surface-subsurface connections, moderate-to-high erosion, and low-to-moderate sediment accumulation rates. The low charcoal levels during this phase indicate limited human impact. The second phase (3500–1400 cal BP) features contrasting depositional environments; the initial interval shows low accumulation under reduced water flow, reflective of a stable late mid-Holocene climate, while the subsequent interval reveals an abrupt shift to wetter conditions, characterized by runoff-derived minerogenic sediments. This period coincides with increased human impacts, including fire activity and land-use changes since the late Bronze Age. The third phase (1400–100 cal BP) exhibits complex hydrological dynamics, with sporadic, intense erosion linked to short-term climatic shifts. Increased charcoal concentrations and the presence of fungi indicate persistent human activity, intensifying after 300 cal BP. Our findings underscore the complex relationship between climate events, humans, and sediment dynamics in the Ciur Izbuc Cave, highlighting the utility of a multi-proxy approach in reconstructing past environmental changes.