Bolătău sediment record – Chronology, microsedimentology and potential for a high resolution multimillennial paleoenvironmental proxy archive

• Detailed microsedimentological and geochronological analysis of Lake Bolătău.
• The landslide event created the lake basin happened at ∼6.8–7 ka.
• The onset of the lacustrine sedimentation started at ∼5–6.5 ka.
• The first ever reported Holocene varved record from the Carpathian region.
• Bolătău has a great potential for future hi-res paleolimnological investigations.

Finely laminated sediment records have been studied from a small landslide-dammed lake (Bolătău) located in Bukovina, Romania. An age-depth model for the Bolătău sediment record was established based on 8 AMS radiocarbon dates from terrestrial macrofossils and the double peaks of the 137Cs flux (i.e. mid-1960s: global fallout maximum; 1986: Chernobyl accident). The onset of the lacustrine sedimentation is estimated to ∼5–6.5 ka while the landslide event can be constrained by ∼6.8–7 ka as an inferior age estimate. The laminated structure is interpreted as organic and clastic type varvite at the lower and upper part of the core, respectively. Major fluctuations found in the coarsely sampled (5 cm) stable carbon isotope data showed remarkable correspondence with nearby palynological records and a lacustrine δ13C record. It suggests that the sediment record preserves environmental signals with a broader regional relevance. The established timescale provides the necessary chronological basis of the records from Lake Bolătău for further analysis.

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