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

大西洋子午线环流(AMOC)是气候系统热通量的重要组成部分，其变化很难预测未来气候变暖。在这个项目中，我们主要关注海洋同位素11阶段，它导致了大约41万年前长达3万年的暖期，其轨道参数与今天相似。格陵兰冰盖的很大一部分已经融化，因此全球海平面比今天高得多。传统的营养替代物提供了在这个特殊的暖期形成强烈深水的证据。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143Nd144Nd值已被证明是一个非常有用的示踪剂。在这个项目中，我们从众多的ODP/IODP沉积岩芯上的自生Fe-Mn矿床中提取了MIS-11和之前的冰期MIS-12(包括V期)期间的自生Fe-Mn矿床的Nd同位素组成。在大西洋，放射性成因较少的钕的显著增加是可以测量到的，这可能表明即使在格陵兰岛冰流失增加的时期，深水形成也更强烈。所调查的沉积物从北到南绘制了整个大西洋深处的地图，以及一些对ND同位素组成有直接区域影响的地区(靠近冰岛)和拉布拉多海。因此，除了在MIS-11期间出现强大的深部环流外，北极水(冰岛-苏格兰海脊溢出)和拉布拉多海水的长期影响也是重要的贡献。在西大西洋深处，在整个间冰期都发现了非常不具放射性成因的ND同位素。在这个扩展项目中，我们想要提高拉布拉多海和开普敦盆地一些沉积物岩心的ND同位素调查的时间分辨率，并完成大量结果的出版，但特别关注与MIS-11、全新世和未来气候变暖的比较。

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.