Timing of Marine Isotope Stage 3 (MIS 3) Climate Change Recorded in Switzerland (TiMIS)

• Unité de recherche: COST
• Numéro de projet: C11.0125
• Titre du projet anglais: Timing of Marine Isotope Stage 3 (MIS 3) Climate Change Recorded in Switzerland (TiMIS)

Mots-clé (Anglais)

Chronologies; Cosmogenic Isotopes Be-10; C-14; Radiocarbon Dating: Bones; Peat; Marine Isotope Stage MIS3; Last Glacial Maximum LGM; Alpine foreland

Programme de recherche (Anglais)

COST-Action ES0907 - The INTIMATE Project: INTegrating Ice core, MArine and TErrestrial records (60,000 to 8000 years ago)

Description succincte (Anglais)

This project aims at refining the radiocarbon chronology of the middle part (middle Würm: 50,000 to 25,000 a) of the last glacial cycle (Last Interglacial to present), which can be observed in the records preserved in the Swiss Alpine forelands where huge piedmont glaciers expanded during the Last Glacial Maximum (LGM). The pioneering research of the Swiss Quaternary scientists of the 1960s and 70s allowed for the location and study of many peat sections, mammoth, and other fauna and plant remains that mark climate changes. In connection to the COST Action ES0907 INITMATE we will undertake the task of radiocarbon dating the well preserved peat sections and associated bones. Application of recent improvements in both lab protocols and AMS measurement techniques will allow us to construct a reliable and robust 14C chronology for selected key sites. Moreover, we propose a new approach that includes 10Be depth profile dating through till (glacial sediments) of the LGM. Results of this study will provide important links to other records of Marine Isotope Stage 3 (MIS 3) as well as add chronological information to the LGM reconstructions in the Swiss Alps.

Partenaires et organisations internationales (Anglais)

AT; BE; DK; EE; FI; FR; DE; EL; HU; IS; IE; IT; LT; NO; PL; PT; RS; ES; SE; CH; UK

Résumé des résultats (Abstract) (Anglais)

The main goal of this project was to refine the radiocarbon chronology of the middle part (middle Würm: 50,000 to 25,000 a) of the last glacial cycle (Last Interglacial to present) based on the records preserved in the Alpine forelands. In connection to the COST Action ES0907 INTIMATE, we performed high-resolution radiocarbon dating of well-preserved peat sections and bones to track pre- LGM climate changes. Results of this study focus on the reconstruction of the timing of events that accompanied LGM ice advance and provide important links to other records of Marine Isotope Stage 3 (MIS 3) as well as add chronological information to the LGM reconstructions in the Alps. While originally focusing on the compressed peat deposits in the Swiss Alpine foreland, the project was extended to investigate peat records from a drilling core in the southern foreland of Italy. This approach provided robust 14C chronologies from key locations in the Alpine foreland and allowed a comparison of climate evolution north and south of the Alps. The high-precision 14C ages obtained from the drilling core additionally provide excellent data to investigate sedimentary processes and link the rate and character of sedimentation to changes in climate and the glacial-interglacial cycle in particular. Obtained chronologies go from the LGM back to the limit of the radiocarbon dating method. Therefore, a major task of this project was the critical evaluation of the available 14C laboratory procedures for preparation of peat and bone samples. Archived bone samples as well as other material prepared and measured at the AMS laboratory of ETH Zurich was studied to set the guidelines for further studies of material as old as 20,000 to 45,000 years. For peat samples, performed extensive testing of various 14C sample preparation protocols and found significant age variability after different sample pretreatment and in few cases also for different sample fractions. Results demonstrate that a careful sample selection with high-resolution sampling is critical to obtain accurate chronologies.

Références bases de données (Anglais)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C11.0125