Late Quaternary Variations in Sediment Provenance and Ice Sheet Dynamics: NE Sector of the Laurentide, Innuitian and the W/NW Margin of the Greenland Ice Sheets

主要研究人员将利用钕、锶和铅同位素数据，以及西北大西洋冰川海洋沉积物中的粘土-粉砂矿物学，研究劳伦蒂德和格陵兰冰盖在最后一个完整冰川循环时间尺度上的动态。 他们的基本前提是，来自冰川海洋的小于65微米部分的矿物学和同位素组成将使他们能够重建各种冰盖的范围及其内部动力学。 该项目包括两个主要部分。 首先，他们将确定在巴芬湾和拉布拉多海的各种冰山“点”来源处进入海洋环境的细粒冰川沉积物的同位素和矿物学特征。 用于点源定性的样品存在于其目前的岩心和表层沉积物样品收集中，或可从加拿大地质调查局的岩心储存设施获得。 这些数据对于冰川沉积物来源的深入研究至关重要，因为它们将表明：1）来自冰盖给定部分的沉积物在矿物学和同位素上是否不同; 2）每个冰山来源是否提供了同位素和矿物学均匀的沉积物。 在第二部分中，主要研究人员将对三个现有的岩芯进行具体的深入研究，以确定沉积物来源、沉积类型、冰盖反应阶段和冰盖/海洋相互作用的变化。 这些岩芯是沿着冰山移动轨迹选取的，应显示来自不同来源区域的沉积物的日益复杂的混合物。 所选岩心来自北方巴芬湾（HU77029-006）、哈德逊海峡口以东的一个地点（HU 97048 -007）以及拉布拉多大陆架中部卡特赖特鞍（HU 87033 -017）。 他们的分析将集中在H139704 S-007，因为它是一个新的核心。 他们将通过获得额外的放射性碳年代来扩大年代控制，并进行一整套沉积学、有孔虫、稳定同位素和物源研究。 这将使他们能够将该岩芯中的数据与目前研究的数据进行比较，并将岩芯矿物学和同位素变化与冰川“点”源的数据进行比较。 这种比较应该为过去5万年来西北大西洋冰盖的范围，配置和动态变化提供新的见解。

AbstractOPP-99-06812FarmerThe Principal Investigators will use neodymiun, strontium, and lead isotopic data, and clay-silt mineralogy from glacial marine sediments in the NW Atlantic Ocean to study Laurentide and Greenland ice sheet dynamics on time-scales of the last full glacial cycle. Their basic premise is that the mineralogic and isotopic compositions of the less than 65 micron fraction from glacial marine will allow them to reconstruct the extent of the various ice sheets and their internal dynamics. The project consists of two main parts. First, they will determine the isotopic and mineralogic character of fine-grained glacial sediments delivered to the marine environment at various "point" sources of icebergs in Baffin Bay and the Labrador Sea. Samples for the point source characterizations exist within their present core and surface sediment sample collections, or are available from the Core Repository Facility at Geological Survey of Canada. These data are critical for downcore studies of glacial sediment provenance because they will indicate if 1) sediments derived from a given portion of the ice sheets are mineralogically and isotopically distinct, and 2) if each iceberg source has provided isotopically and mineralogically homogeneous sediment. These characteristics must be established before any attempt to reconstruct ice sheet dynamics from sediment provenance studies can be attempted.In the second part, the Principal Investigators will undertake specific downcore studies on three existing cores to determine changes in sediment provenance, style of deposition, phasing of ice sheet reactions, and ice sheet/ocean interactions. These cores have been selected along the iceberg transport trajectory and should show increasingly complex mixtures of sediment from different source regions. The cores selected are from northern Baffin Bay (HU77029-006), from a site east of the mouth of Hudson Strait (HU97048-007), and, south, from Cartwright Saddle on the central Labrador shelf (HU87033-017). Their analyses will concentrate on H139704S-007 because it is a new core. They will expand the chronological control by obtaining additional radiocarbon dates and undertake a full suite of sedimentological, foraminiferal, stable isotopic, and provenance studies. This will enable them to compare data in this core with data from present studies and to compare downcore mineralogic and isotopic variations to those of the glacial "point" sources. This comparison should provide new insights into changes in the extent, configurations, and dynamics of ice sheets around the NW Atlantic over the past 50 thousand years.