Oceanic and atmospheric variations during the last deglaciation in the Fram Strait (Arctic Ocean): a coupled high-resolution organic-geochemical and sedimentological study

摘要

From a high sedimentation rate core, obtained from the Yermak slope (Arctic Ocean), we deduced short-term climatic fluctuations of the last deglaciation lasting from 17,000 to 9000 years BP. By using a coupled organic- geochemical and sedimentological approach, we reconstructed near-bottom current conditions and assessed their significance in relation with comparable global thermohaline circulation patterns and surface water conditions. Highest concentrations and fluctuations of specific marine phytoplankton biomarkers were obtained in the Boiling-Allerod, when the major deglaciation of the Svalbard-Barents-Sea-Ice-Sheet (SBIS) occurred. The marine biomarker record and the sedimentological record are consistent with climate reconstructions obtained from Greenland ice cores and thermohaline circulation variations. However, beginning with the Younger Dryas (YD) episode, bottom currents decreased during this time period, but surface waters remained very productive. The atmospheric conditions of the western Fram Strait (reconstructed from biomarker data) and thermohaline circulation signals (reconstructed from sedimentological data) were decoupled in the YD. Maximum insolation values of solar radiation and "Fohn"-like winds enabled open water conditions and increased productivity values in the northern Fram Strait, at least in summer. (C) 2003 Elsevier Ltd. All rights reserved.