白令海北部陆坡BR07孔年龄框架重建

摘要

通过对比白令海BR07孔与B5-4孔硅藻百分含量、颜色反射率等参数结果，综合建立了BR07孔年龄框架。根据该重建年龄结果，BR07孔年龄约为11.3～1.9 ka ，平均沉积速率约为28.5 cm/ka ，略低于B5-4孔。基于圆柱拟脆杆藻与塞米新细齿藻比值 Fragilariopsis cylindrus含量/（Fragilari-opsis cylindrus含量＋ Neodenticula seminae含量）重建的近万年来白令海海冰变化历史，记录到该区域末次冰消期以来包括新仙女木事件在内的3次冷事件以及1次暖事件，其中新仙女木事件约发生于距今11.3～10.7 ka ，与格陵兰冰心记录对应值距今12.9～11.6 ka基本相近，这进一步佐证了该重建年龄比原始的全样有机碳 AMS 14 C测年结果更可信。%T he age model of Core BR07 is reconstructed based on the comparisons of diatom distributions and color parameters of the sediments between Cores B 5-4 and BR07 ,both collected from the northern continental slope of the Bering Sea .According to this age model ,the deposition ages of Core BR07 range from 1.9 to 11.3 kaBP ,with an average sedimentation rate of 28.5 cm/ka which is slightly lower than that of Core B5-4 .A sea-ice proxy ,de-fined as the ratio of Fragilariopsis cylindrus content to (F .cylindrus content+ Neodenticula seminae content) ,is proposed to reconstruct the historic climate record of sea-ice changes over the last 10 ka .Three cold events (inclu-ding the Younger Dryas cold event ) as well as one warm event since the last deglacial period have been detected in the core .T he reconstructed time span of the Younger Dryas cold event in Core BR 07 is 11.3~10.7 ka BP ,close to its correspondent of 12.9~11.6 ka BP from Greenland ice cores ,further confirming that it is more reliable than the age generated from the radiocarbon dating of the bulk sediment organic carbon .