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有关冰岛，格陵兰岛东部和拉布拉多大陆架周围一系列地点的石英和白云石矿物浓度和通量的数据，目的是研究这些特定矿物物种的全新世时空变异性，以衡量流冰的存在或不存在以及严重程度。流冰的范围和持续时间的变化（即，北大西洋边缘海（格陵兰海、冰岛海和巴芬湾/拉布拉多海）的海冰（包括冰山和各种形式的海冰）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。 重建IRD（冰筏碎片）向北大西洋站点的输送变化（基于赤铁矿染色石英砂颗粒的计数）显示，从12，000年前到现在，IRD总体减少，一系列振荡间隔约1，500年。 与此相反，东格陵兰大陆架冰川部分的IRD显示了一个中全新世的小IRD间隔，随后在过去的5000 - 6000年期间强烈增加。初步结果表明，北大西洋地区全新世IRD被捕获在赤铁矿染色的石英变化中，以1,500年的周期为主，是不正确的，需要除流冰以外的机制来解释普遍的信号。 这项研究将有助于解决一个难题，即为什么北大西洋的海洋站点在对气候变化的沉积学反应信号方面存在差异。 该研究战略加强了美国、加拿大、挪威和德国科学家之间的国际合作。

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.