Abrupt Climate Change During Marine Isotope Stage 3 in Southern Tropical Africa: Multiproxy Reconstructions from Lake Tanganyika

海洋同位素第三阶段（MIS 3）是距今约3万至6万年的时期，其特征是北方许多地点记录到的大规模、突然的千年尺度变暖。来自南极洲和南半球中纬度地区的记录表明，当北半球变暖时，南半球变冷，这是海洋和大气中“两极跷跷板”的一部分。然而，几乎没有来自南部热带或热带非洲的记录来测试这种模式的空间范围，尽管热带地区在同步，传播和触发千年尺度气候变化方面具有潜在的重要性。该赠款将使用坦噶尼喀湖的沉积物岩心调查南部热带非洲MIS 3千年尺度的变化。该项目将应用敏感的新代理，包括脂肪酸的del-D，TEX 86古温度计，del-15 N，del-13 C和%生物硅，以重建有效的降水，温度和古湖泊的变化在一个基于加速器质谱碳-14测年的年表框架内。这项工作将提供重要的见解，以了解南热带地区千年尺度的变化、触发和传播气候突变的机制、热带非洲“冰川干旱”的演变以及坦噶尼喀湖上升流和生产力的控制。了解千年尺度气候变化的空间模式将产生对了解其基本物理和机制至关重要的信息，并将为检验气候模式模拟气候突变的能力提供基础数据。南半球的热带地区是至关重要的半球间的热量和水分转移在气候突变，但南部的热带地区，特别是热带非洲，代表性差的网络MIS 3 records.Broader影响：这项研究将提供一个新的记录，从一个干旱易发，人口稠密的地区，其气候历史知之甚少的气候变率。这项研究将促进多学科的方法来调查古气候，并将导致一个研究生论文和本科生的跨学科实验室技术的培训。坦噶尼喀湖是非洲裂谷盆地地质学、湖泊特有现象、湖沼学和古气候学研究中最重要的湖泊之一。这项工作将深入了解湖泊湖沼学和生产力的长期控制，并将使用创新的新工具来调查沉积记录。

Marine Isotope Stage 3 (MIS3), a period from ~30,000 to 60,000 years before present, is characterized by large, abrupt millennial-scale warmings recorded at numerous sites in the northern hemisphere. Records from Antarctica and the southern mid-latitudes suggest that the southern hemisphere cools when the North warms as part of a 'bipolar seesaw' in the oceans and atmosphere. However, there are virtually no records from the southern tropics or from tropical Africa to test the spatial extent of this pattern, despite the potential importance of the tropics in synchronizing, propagating, and triggering millennial-scale climate change. This grant will investigate MIS3 millennial-scale variability in southern tropical Africa using sediment cores from Lake Tanganyika. The project will apply sensitive new proxies including the del-D of fatty acids, the TEX86 paleothermometer, del-15N, del-13C, and % biogenic silica to reconstruct effective precipitation, temperature, and paleolimnologic variability in the lake within an chronologic framework based on accelerator mass spectrometry carbon-14 dating. This work will provide important insight into millennial-scale variability in the southern tropics, the mechanisms triggering and propagating abrupt climate changes, the evolution of "glacial aridity" in tropical Africa, and the controls on upwelling and productivity in Lake Tanganyika.Intellectual Merits: Understanding the spatial patterns of millennial-scale climate changes will yield information critical to understanding their underlying physics and mechanisms, and will provide fundamental data to test the ability of climate models to simulate abrupt climate change. The southern hemispheric tropics are crucial to interhemispheric heat and moisture transfer during abrupt climate changes, yet the southern tropics, and in particular tropical Africa, are poorly represented in the network of MIS3 records.Broader Impacts: This research will provide a new record of climate variability from a drought-prone, densely inhabited region whose climate history is poorly known. This study will promote multidisciplinary approaches to investigating paleoclimate, and will result in one graduate student dissertation and the training of undergraduate students in cross-disciplinary laboratory techniques. Lake Tanganyika is one of the most important lakes in Africa for studies of rift basin geology, lacustrine endemism, limnology, and paleoclimatology. This work will provide insight into the long-term controls on the lake's limnology and productivity, and will use innovative new tools to investigate the sedimentary record.