Oldest Dryas hydroclimate reorganization in the eastern Iberian Peninsula after the iceberg discharges of Heinrich Event 1

• Published in: Quaternary Research
• Main Authors: Perez-Mejias, Carlos, Moreno, Ana, Bernal-Wormull, Juan, Cacho, Isabel, Cinta Osacar, M., Lawrence Edwards, R., Cheng, Hai
• Format: Report
• Language: English
• Published: CAMBRIDGE UNIV PRESS 2021
• Subjects: Speleothem; Deglaciation; Heinrich Stadial 1; Oldest Dryas; Iberia; Western Mediterranean; Atlantic Meridional Overturning Circulation; LAST GLACIAL MAXIMUM; ATLANTIC SURFACE HYDROGRAPHY; NORTH-ATLANTIC; CLIMATE VARIABILITY; ALBORAN SEA; VEGETATION HISTORY; SPELEOTHEM RECORD; HYDROLOGICAL VARIABILITY; EUROPEAN DEGLACIATION; REGIONAL CLIMATE; Physical Geography; Geology; Geography; Physical; Geosciences; Multidisciplinary; North Atlantic
• Online Access: http://ir.ieecas.cn/handle/361006/16699; http://ir.ieecas.cn/handle/361006/16700; https://doi.org/10.1017/qua.2020.112

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 parts per thousand in delta C-13 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 delta O-18 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.