Early to mid-Holocene hydroclimate trends in the western Carpathians of Romania

Abstract In this study, we analyse a sequence from Ic Ponor ombrotrophic peat bog in the Apuseni Mountains of NW Romania using a multi-proxy approach (testate amoebae, pollen, microcharcoal, loss on ignition, magnetic susceptibility, radiocarbon dating, lithology) to reconstruct the palaeoenvironmental conditions and the hydroclimate trends that occurred between 12,700 and 6220 cal yr BP. The sequence evolved from a lacustrine phase (between 12,700 cal yr BP and 12,000 cal yr BP) into an ombrotrophic peat bog (12,000–7600 cal yr BP), accumulated in drier climate conditions, with a subdued water table. Subsequently, wetter conditions occurred, with an elevated water table until 6220 cal yr BP, when the peat bog was flooded and peat accumulation paused, a depositional hiatus being marked by a clayey layer. Peat started to accumulate again ca. 100 years ago, under drier conditions. The peat bog records the local and regional responses to rapid climate change events that occurred at 11400–11250, 10,500–10,200, 9400–9200, and 8300–8250 cal yr BP. Our quantitative reconstruction of hydrological changes, as well as pre-existing ones for this region, show similar conditions to those that occurred in Central-Eastern Europe between 12,700 and 7600 cal yr BP, but differ from those that occurred between 7600 and 6220 cal yr BP, suggesting a distinct regional character of Middle Holocene climate conditions in Romania.