Palaeohydrological changes during the mid and late Holocene in the Carpathian area, central-eastern Europe

Multi-proxy, high-resolution analyses (lithological, geochemical, environmental magnetism) anchored by 22 14C dates, of a 5.53 m long sediment core from Lake Ighiel (Romanian Carpathians, central-eastern Europe) allowed the reconstruction of key local, catchment-lacustrine dynamics and an appraisal of palaeohydrological and palaeoclimatic gradients acting regionally over the last 6000 years. The first sedimentological phase of the record from 6030 to 4200 cal yr BP is characterised by low productivity and high detrital input indicating surface runoff processes due to enhanced rainfall. This interpretation is in agreement with other hydrological reconstructions reporting increased precipitation also in CE Europe, NE Mediterranean and also inferred summer and winter latitudinal temperature gradients (LTG) (as defined by Davis and Brewer, 2009), showing a strong connectivity between basin-lacustrine dynamics and the establishment of the dominant, Atlantic atmospheric circulation pattern in the area. The lacustrine system was more stable between 4200 and 2500 cal yr BP when clastic inputs diminished and biological productivity increased. During this interval, the coherence of Lake Ighiel's multi-century detrital events, identified in a range of proxy-data (albeit different in frequency and magnitude), with flood activity in central Europe (the Alps) suggests a common moisture forcing (Atlantic and periodically Mediterranean influences). In contrast, different reconstructions from the NE Mediterranean indicate a distinct NW-SE hydro-climatic gradient. A more complex and variable trend is depicted in Lake Ighiel sedimentation during the last ~ 2500 years showing a variable detrital trend likely reflecting an intriguing hydrological pattern which is in agreement with intervals of increased aridity phases during a generally moister period. Comparing our sedimentological results with published pollen records from the nearby area clearly indicates anthropogenic imprints during the Dacian-Roman Period and especially from the Middle Ages towards the present. The ~ 6000-year long sedimentary record of Lake Ighiel contributes to our understanding of mid and late Holocene palaeohydrological changes in the Carpathians and highlights the importance of latitudinal gradients in driving hydrological variability in continental Europe.