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DDC:
550 - Earth sciences
Abstract:
This study presents multi-proxy data from a new core from Lago Grande di Monticchio (Italy) extending back to about 100,000 calendar years BP. The time scale of this record is independent from deep-sea and ice-core chronologies and has been established from a combination of varve counts and high-resolution sedimentation rate calculations based on microscopic sediment investigation. This paper focuses on environmental variability between 100,000 and 65,000 calendar years BP. Several abrupt cold periods have been recognised and correlated to other terrestrial as well as to ice-core and deep-sea records. The longest of the Monticchio cold phases corresponds to Marine Isotopic Stage 5b and lasted from ca 87,000 to 84,000 calendar years BP. Two shorter events (about 1000 years long) occurred during the transition from interstadial to full glacial conditions between 79,000 and 75,000 calendar years BP. The increased frequency of cold events during this time interval probably indicates a higher degree of climatic instability in periods of major changes. Dating discrepancies between Monticchio, GRIP, and deep-sea chronologies range between a few hundred to a few thousand years. However, these differences in dating are not constant but vary significantly for different sections of the records. Nevertheless, the good match of environmental fluctuations at Monticchio with atmospheric variability at the Greenland Summit as well as variations in the oceanic circulation pattern suggests a close link of the Mediterranean to the Atlantic climate regime.
