C04_04

European Glacial tree-ring chronologies - New high-resolution ¹⁴C-series

Friedrich M¹, Kromer B², Cercatillo S³, Wacker L⁴, Toniello V⁵, Bicho N⁶, Horta P⁶, Adolphi F⁷, Muscheler R⁸, Talamo S³

¹Hohenheim Gardens (772), University of Hohenheim, D-70599 Stuttgart, Germany, ²Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany, ³Department of Chemistry G. Ciamician, Alma Mater Studiorum, University of Bologna, Bologna, Italy, ⁴Laboratory of Ion Beam Physics, ETH Zurich, Zurich, Switzerland, ⁵Gruppo Speleologico C.A.I. di Vittorio Veneto (TV), Vittorio Veneto, Italy, ⁶Interdisciplinary Centre for Archaeology and the Evolution of Human Behavior, University of Algarve, Faro, Portugal, ⁷Helmholtz Centre for Polar and Marine Research, Alfred Wegener Institute, Bremerhaven, Germany, ⁸Department of Geology, Quaternary Sciences, Lund University, Lund, Sweden

The ¹⁴C-calibration curve IntCal is a key-record in paleosciences that provides a chronological framework for a wide range of disciplines studying environmental and cultural changes during the late Pleistocene and the Holocene. Tree-rings directly record atmospheric ¹⁴C/¹²C relationship at their time of growth and are thus the ideal natural archive to construct a terrestrial calibration curve - if they can be well dated. However, they are continuously available only back to 14.226 years BP.  Before this time, the resolution of the calibration curve drops substantially, or relies on ¹⁴C data that do not directly reflect atmospheric ¹⁴C.

In the Late Pleistocene, a number of floating tree-ring ¹⁴C-series from subfossil trees exist, that can provide snapshots of past ¹⁴C-variability and have a tremendous potential. The challenge here is to establish their absolute chronology by providing high-resolution ¹⁴C-dates with tight error ranges, because that is the prerequisite e.g. for successful comparisons of the solar induced decadal to sub-centennial ¹⁴C-variability to the ¹⁰Be-record of the ice cores.

In this contribution, we present newly constructed Glacial tree-ring chronologies of subfossil trees from northern Italy and Portugal at 18ka resp. 32ka BP, and respective high precision, sub-decadal ¹⁴C-series achieved by the ERC-project ‘RESOLUTION’. We discuss their absolute chronological dating by comparisons with terrestrial calibration series and the possibility to infer links to the Greenland ice core timescale.

The new tree-ring based ¹⁴C-series will contribute to characterize past atmospheric ¹⁴C variability and will improve the radiocarbon calibration towards achieving a precise high-resolution chronology of human evolution.