C03_04

Annual dating of Late Glacial trees from the French Alps. Implications of a spike at ca. 14.3 cal kyr BP

Bard E¹, Miramont C², Capano M¹, Guibal F², Marschal C², Rostek F¹, Tuna T¹, Fagault Y¹

¹CEREGE, Aix-en-provence, France, ²IMBE, Aix-en-Provence, France

We present new ¹⁴C results measured on subfossil Scots pines recovered in the eroded banks of the Drouzet watercourse in the region of the middle course of Durance River in the Southern French Alps. Recent fieldwork enabled us to complement previous studies starting with Miramont et al. (2000 Radiocarbon). Dendro-matching of wood sequences allowed to construct 3 chronologies with durations ranging between 200 and 400 years, each including between 23 to 59 individual trees. Selected trees were sampled at annual resolution and every third ring was pretreated by using methods previously developed for trees from the nearby site of Barbiers (Capano et al. 2018, 2020 Radiocarbon included in IntCal20 Reimer al. 2020 Radiocarbon). So far, about 400 new ¹⁴C ages were measured on 15 trees, which allowed to construct a ≈ 700-yr long chronology. Preliminary matching with the Late Glacial German pine chronology shows that the Drouzet chronology reaches ca.14.4 cal kyr BP. The resulting ∆¹⁴C record exhibits a century-long event between 14 and 13.9 cal kyr BP and a large and abrupt spike occurring in a single year around 14.3 cal kyr BP (evidenced in 2 dendro-matched trees). We will compare our record with that obtained in a floating tree from Northern Italy (Adolphi et al. 2017 QSR). The abrupt spike around 14.3 cal kyr BP, together with the length of the Drouzet record and its long overlap with the German pine chronology should be helpful to refine the comparison and tuning between the Greenland ice and IntCal chronologies.