Collaborative Research: Development of paleo-proxy to test the sensitivity of the Southern Greenland Ice Sheet to future warming

该奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。麦迪逊在对地理信息系统行为的古重建中，一个重要的缺失因素是缺乏一个明确的冰盖示踪剂。利用格陵兰南部不同的基岩地体年龄(太古代与不同的元古界年龄)，提出了利用陆源标记和格陵兰南部不同的基岩地体年龄来开发格陵兰冰盖退缩和航空范围的示踪剂。具体地说，将从格陵兰岛南部的地质地体中采集溪流中的悬浮泥沙。将对悬移质沉积物进行微量元素和锶-钕-铅同位素组成的测定，并测定沉积物的磁性。这些数据将与以前在格陵兰岛南部外的一个岩芯上进行的新测量进行比较，这些测量是从一个经过充分研究的沉积序列得出的，该沉积序列跨越了过去430年和5个间冰期。活塞芯样品的同位素研究将重点放在粉粒含量上，以最大限度地减少远距离移动的粘土粒度沉积物的影响。冰排沉淀物也将被避免。结合以前和新获得的磁性记录，微量元素记录将通过确定冰盖退缩的时间和持续时间来估计南部地理信息系统对气候变暖的反应时间。锶-钕-铅同位素示踪剂将能够计算沉积物来源以及冰从格陵兰岛南部部分地区退缩的时间，从而估计其对更高海平面的贡献。特别是，核心处相对年轻的元古界沉积物的消失将地理信息系统南部边缘置于其当前位置的后面。随后太古宙沉积减少，中元古代沉积占优势，形成格陵兰中部的南缘。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Carlson 0902571University of Wisconsin ? MadisonA significant missing component in paleo-reconstructions of GIS behavior has been the lack of an unambiguous ice sheet tracer. The development of such a tracer for the Greenland Ice Sheet (GIS) retreat and aerial extent is proposed using terrigenous provenance markers and the different bedrock terrane ages of southern Greenland (Archean versus varying Proterozoic ages). Specifically, streams will be sampled for suspended load sediment from the geologic terranes of southern Greenland. Suspended load sediment will be measured for trace-element and Sr-Nd-Pb isotope composition, and magnetic properties of the sediment will be determined. These data will be compared with previously made and new measurements on a core off of southern Greenland from a well-studied sediment sequence spanning the last 430 kyrs and 5 interglacials. Isotope studies on piston core samples will focus on the silt size fraction in order to minimize the influence of far traveled clay size sediment. Ice rafted sediment will also be avoided. Trace element records combined with previous and newly obtained magnetic records will provide estimates of the response time of the southern GIS to a warming climate by identifying the timing and duration of ice sheet retreat. The Sr-Nd-Pb isotope tracers will allow calculations of sediment sources and when ice retreated off portions of southern Greenland, thus estimating its contribution to higher sea levels. In particular, the disappearance of relatively young Proterozoic sediment at the core site places the southern GIS margin behind its current location. A subsequent reduction in Archean sediment and dominance of intermediate age Proterozoic sediment places the southern GIS margin in central Greenland.