Evidence from Fram Strait (78 Deg N) for Early Deglaciation

摘要

Recent syntheses of the history of the last Northern Hemisphere glaciation and deglaciation illustrate that understanding of the mechanisms and timing of deglaciation before approximately 12,000 years BP is limited. After 12,000 yr BP, however, there is sufficient evidence from radiocarbon-dated moraines, raised beaches, varved lake sediments and pollen records to provide a reasonable temporal and geographic picture of the decay of the ice sheets. Here we report on the first oxygen isotope record from the Norwegian-Greenland Sea that is radiocarbon-dated directly by accelerator mass spectrometry. A significant light-oxygen-isotope event is recorded at approximately 15,000 years BP which suggest that the marine-based Barents Shelf ice sheet disintegrated rapidly at this time. Recent studies have estimated that the decay of this ice sheet could have contributed as much as 15 metres to eustatic sea-level rise. The decay of the Barents Shelf ice sheet is the earliest major deglacial event yet dated, and may have triggered subsequent deglacial events through eustatic sea-level effects. Reprints. (fr)