Grain size analysis of sediments from deep Lake Malawi

我们建议研究马拉维湖活塞芯的全新世和末次冰川段。这将通过高分辨率数字图像分析(样本宽度为300(M)的薄片，基于Seelos&Sirocko，2005年开发的半径方法)来完成。马拉维沉积物为部分叠层，平均沉积速率为0.33毫米/年。因此，粒度记录将具有年度分辨率，并能够探测风尘暴缩和河流洪水的历史，提供过去25.000年来赤道非洲气候变化的年度分辨率时间序列，特别是评估北半球寒冷事件期间的低纬气候，如小冰期、8.2ka事件、年轻仙女座和海因里希事件。这项工作也是一项方法论研究，因为我们将不得不开发一种新的半径算法来处理大型湖泊的超细颗粒沉积物。当这一算法在项目的第一年成功开发时，这项研究可以继续到过去对ICDP马拉维沉积物的研究，但也可以应用于来自深湖的其他ICDP岩芯。

We propose to study the Holocene and last glacial sections of a well dated piston core from lake Malawi. This will be done by high resolution digital image analysis (sample width of 300 (m) of thin sections, based on the RADIUS method developed by Seelos & Sirocko, 2005. The Malawi sediments are partly laminated with an average sedimentation rate of 0.33 mm/yr. Thus the grain size record will have annual resolution, and allow to detect the history of eolian dust deflation and riverine flash floods, presenting an annual resolution time series of climate change in equatorial Africa for the last 25.000 years, in particular evaluating the low latitude climate during northern hemisphere cold events like the Little Ice age, the 8.2 ka event, Younger Dryas and Heinrich Events. This work is also a methodological study, because we will have to develop a new RADIUS algorithm for the very fine grained sediments of large lakes. When this algorithm is developed successfully in the first year of the project, the study can be continued further into the past on the ICDP Malawi sediments, but be also applied to other ICDP cores from deep lakes.