The Holocene History of Drift Ice at the Present-Day Limits Off North Iceland and the Eastern Canadian Margin

该奖项使用资金收集和分析冰岛、东格陵兰岛和拉布拉多大陆架周围一系列地点的石英和白云岩矿物浓度和通量数据，目的是研究这些特定矿物物种的全新世时空变化，作为漂移冰存在与否和严重程度的衡量标准。北大西洋边缘海域（格陵兰海和冰岛海以及巴芬湾/拉布拉多海）的漂冰（即冰山加上各种形式的海冰）的范围和持续时间的变化影响着邻近陆地地区的气候，其影响可通过大气和海洋环流向下游传播。对北大西洋地区冰筏碎屑（IRD）运送变化的重建（基于赤铁矿染石英砂颗粒的计数）显示，从12000年前到现在，IRD的总体减少，一系列振荡间隔约为1500年。与此相反，格陵兰东部陆架的冰川碎屑的IRD在全新世中期出现了一个较小的IRD间隔，随后在最近5000 - 6000年间出现了一个强劲的增长。初步结果表明，普遍接受的北大西洋地区全新世IRD是在赤铁矿染石英变化中捕获的，以1500年的周期性为主，这是不正确的，需要漂移冰以外的机制来解释普遍存在的信号。这项研究将有助于解决一个各种各样的难题，即为什么北大西洋的海洋地点对气候变化的沉积反应信号不同。该研究战略在美国、加拿大、挪威和德国的科学家之间建立了强有力的国际合作。

This award uses funds to collect and analyze data on quartz and dolomite mineral concentrations and fluxes in a series of sites around Iceland, east Greenland, and the Labrador shelf, with the goal of examining the Holocene spatial and temporal variability of these specific mineral species as measures of drift ice presence or absence and severity. Variations in the extent and duration of drift ice (i.e., icebergs plus various forms of sea ice) in the marginal Seas of the North Atlantic (the Greenland and Iceland Seas, and Baffin Bay/Labrador Sea) influence the climate of adjacent land areas and whose effects can be propagated downstream by both atmospheric and ocean circulation. Reconstructions of variations in the delivery of IRD (ice-rafted debris) to sites in the North Atlantic (based on counts of hematite-stained quartz sand grains) show an overall decrease in IRD from 12,000 years ago to the present, with a series of oscillations spaced at ~1,500 year intervals. In contrast, the IRD on the glacial fraction from sites on the east Greenland shelf show a mid-Holocene interval of little IRD followed by a strong increase during the last 5,000-6,000 years.Initial results suggest that the generally accepted paradigm that Holocene IRD in the North Atlantic region is captured in hematite-stained quartz variations, dominated by a 1,500-yr periodicity, is not correct and that mechanisms other than drift ice are required to explain the pervasive signal. The research will help solve a puzzle of sorts as to why marine sites in the North Atlantic differ in their signal of sedimentological response to climate variability. The research strategy posses strong international collaborations between scientists in the United States, Canada, Norway, and Germany.