This study examines the first precisely dated and temporally highly resolved speleothem record from Iberia that reconstructs the Oldest Dryas (OD). The onset of cold conditions in the study area, contemporary with the beginning of Heinrich Stadial 1, is recorded at 18.13 ± 0.08 ka, with a pronounced drop of 6.1‰ in δ13C in 250 years. Henceforth, stadial conditions depict a period of instability in the Atlantic Meridional Overturning Circulation, peaking in freshwater input from iceberg melting during Heinrich Event 1. Anomalies in the δ18O of the stalagmite attributed to such a freshwater event are found from 16.17 to 15.89 ka. Such absolute dates given to the onset of the OD in Iberia and to the main iceberg discharges are reliable anchor points for non-absolute chronologies. Two periods are identified in the OD: OD-a (18.13-16.17 ka) is characterized by wet conditions and a faster growth rate, and OD-b (15.89-14.81 ka) exhibits relative dryness and a slower growth rate. The sudden release of fresh water is considered to be the reason for the disruption of rainfall patterns in eastern Iberia. The present study also highlights the existence of heterogeneous and complex hydrological conditions during the OD in Iberia when both Atlantic and Mediterranean realms are considered.
Bibliographical noteFunding Information:
We acknowledge funding received from NSFC 41888101 to Cheng and Pérez-Mejías; NSF grant 1702816 to Lawrence Edwards and Cheng; and CGL2016-77479-R (SPYRIT) and CTM2016-75411-R (CHIMERA) to Moreno and Cacho, respectively. The authors would like to acknowledge the use of Servicio General de Apoyo a la Investigación-SAI, University of Zaragoza, and the help of all those involved during the field work. This is a contribution of the research groups “Procesos geoambientales y cambio global” (E02_17R) and “Geotransfer” (E32_17R and E32_20R) from the Aragón Government, Pyrenean Institute of Ecology, and University of Zaragoza. We thank the senior editor, Lewis Owen, the guest editor, Dominik Faust, and the two anonymous reviewers for the constructive comments that improved the manuscript.
Copyright © University of Washington. Published by Cambridge University Press, 2021.
- Atlantic Meridional Overturning Circulation
- Heinrich Stadial 1
- Oldest Dryas
- Western Mediterranean