Ice-rafting history in the Labrador Sea during the last millennium@en

Arctic freshwater discharges to the Labrador Sea from melting glaciers and sea-ice can have a deep impact on ocean circulation dynamics in the North Atlantic, modifying climate and deep water formation in this region. In this study, we present for the first time a high resolution record of ice-rafting in the Labrador Sea over the last millennium to assess the effects of freshwater discharges in this region on ocean circulation and climate. The occurrence of ice-rafted debris (IRD) in the Labrador Sea was studied using sediments from Site GS06-144-03 (57.29° N, 48.37° W, 3432 m water depth). IRD from the fraction 63-150 µm shows particularly high concentrations during the intervals: ~1000-1100, ~ 1150-1250, ~1400-1450, ~1650-1700 and ~1750-1800 yr AD. The first two intervals occurred during the Medieval Climate Anomaly (MCA), whereas the others took place within the Little Ice Age (LIA). Mineralogical identification indicates that the main IRD source during the MCA was SE Greenland. In contrast, the concentration and relative abundance of hematite-stained grains reflects an increase in the contribution of Arctic ice during the LIA. […]北极冰川与海冰消融后注入拉布拉多海的淡水径流，可对北大西洋的海洋环流动力学产生深远影响，进而改变该区域的气候与深层水形成过程。本研究首次发布了过去千年尺度下拉布拉多海冰筏沉积的高分辨率记录，以评估该区域淡水径流对海洋环流与气候的影响。本研究依托GS06-144-03站位（北纬57.29°，西经48.37°，水深3432米）的沉积物样品，对拉布拉多海的冰筏碎屑（ice-rafted debris, IRD）产出特征展开研究。粒度介于63–150 µm的IRD组分在以下时段呈现显著高浓度：公元1000–1100年、1150–1250年、1400–1450年、1650–1700年以及1750–1800年。前两个时段处于中世纪气候异常（Medieval Climate Anomaly, MCA），其余时段则属于小冰期（Little Ice Age, LIA）。矿物学鉴定结果显示，中世纪气候异常期期间IRD的主要物源为格陵兰东南部；与之相反，小冰期阶段赤铁矿染色颗粒的浓度与相对占比则反映出北极冰源贡献的提升。[...]