MIS-11: A Super-Interglacial with enhanced North Atlantic Deep Water Circulation

大西洋经向环流（AMOC）是气候系统热通量的重要组成部分，其变化对未来气候变暖的影响难以预测。在这个项目中，我们专注于海洋同位素阶段（MIS）11，这导致了大约41万年前的3万年的温暖期，与今天相比，轨道参数相似。格陵兰岛的大部分冰盖已经融化，因此全球海平面明显高于今天。传统的营养盐代用指标提供了在这一特定的温暖时期形成强大的深水的证据。为了重建水团的来源、流动路径和混合比，深海沉积物自生相的143 Nd/144 Nd同位素比值已被证明是一个非常有用的示踪剂。在这个项目中，我们已经提取了Nd同位素组成的自生铁锰矿床在许多ODP/IODP沉积物芯，持续的MIS-11和以前的冰河时期MIS-12（包括终端V）。在大西洋，可测量到放射性较低的钕的显着增加，这可能表明即使在格陵兰岛冰损失增加的时期，也有更强的深水形成。调查的沉积物映射整个深大西洋从北到南，以及一些地区的Nd同位素组成的直接区域影响（冰岛附近）和拉布拉多海。因此，除了MIS-11期间强大的深层环流之外，还可以证明北极水（冰岛-苏格兰海脊溢出）的重要贡献和拉布拉多海水的长期影响。在整个间冰期，在西大西洋深处发现了非常非放射性的Nd同位素值。在这个扩展项目中，我们想提高时间分辨率的Nd同位素调查的一些沉积物芯从拉布拉多海和开普盆地，并完成大量的结果的出版物，但特别注重MIS-11，全新世，和未来的气候变暖的比较。

The Atlantic Meridional Circulation (AMOC) is an essential component of the heat fluxes in the climate system, whose change is difficult to predict with regard to future climate warming. In this project, we focus on the Marine Isotope Stage (MIS) 11, which led to a 30,000 year long warm period about 410,000 years ago with similar orbital parameters as compared to today. A large part of the Greenland ice sheet had melted and as a result the global sea level was significantly higher than today. Traditional nutrient proxies provide evidence of strong deep water formation during this particular warm period. In order to reconstruct the provenance of the water masses, their flow paths, and the mixing ratios, the isotope ratio 143Nd/144Nd in the authigenic phase of deep-sea sediments has proved to be a very useful tracer. In this project, we have extracted the Nd isotopic composition from such authigenic Fe-Mn deposits on numerous ODP/IODP sediment cores, for the duration of MIS-11 and the previous ice age MIS-12 (including Termination V). In the Atlantic Ocean, a significant increase of less radiogenic neodymium is measurable, which probably shows a stronger deep water formation even during periods of increased ice loss on Greenland. The investigated sediments map the entire deep Atlantic from north to south, as well as some regions with direct regional influence on the Nd isotope compostion (near Iceland) and the Labrador Sea. In addition to a strong deep circulation during MIS-11, an important contribution of Arctic water (the Iceland-Scotland Ridge Overflow) and a long-lasting influence of water from the Labrador Sea could thus be demonstrated. In the deep West Atlantic very unradiogenic Nd isotope values are found throughout the interglacial period. In this extension project, we would like to improve the temporal resolution of Nd isotope investigations of some sediment cores from the Labrador Sea and Cape Basin and accomplish publications of the large amount of results, but with particular focus on the comparison of MIS-11, the Holocene, and a future warmer climate.