Dynamics of North African Humid Periods of the last 130 kyr

地质数据和模型模拟记录了第四纪晚期反复出现的非洲湿润期。他们每个人都有自己的风格。10 kyr，对应于一个更短的时间间隔腐泥形成在深东地中海（EMS）。由于只有很少的详细地质记录，数值环流模型没有绘制出统一的图像，因此关于潮湿时期的动态仍然存在争议，特别是景观演变的性质，西非和东非记录之间的不对称性，潮湿时期开始和结束期间的动态，和可能的生物物理气候和植被之间的反馈。在我们提出的研究中，我们计划从远端的角度来处理这些开放的问题，重建从北非到EMS的粉尘通量的强度和动态。我们将通过从EMS的关键位置回收的三个沉积物岩心产生高分辨率数据集来实现这一目标。岩芯中含有过去13万年的沉积物，包括腐泥层S1至S5和相应的湿润期。GeoTü SL 110岩芯是从靠近以色列海岸的东南黎凡特海的尼罗河排放羽流中提取的，应记录季风驱动的河流沉积物输入的变化。SL 99岩心来自西南部的黎凡特海，靠近利比亚的北非海岸。它应主要受撒哈拉中部和东部的尘埃通量的影响，并应记录该地区的水文历史。SL 71岩心来自克里特岛西南部的爱奥尼亚海。我们的初步研究表明，在这个核心中，我们可以区分来自北方和南方的气候信号。我们希望特别调查太阳辐射、季风活动、降水、植被覆盖、河流径流、风蚀和风成输送的相互作用。我们最感兴趣的是非洲湿润期的时间，对他们的逐渐与突然的开始和结束，干旱化/尘埃运输和降水/河流排放之间的关系。为此，我们打算应用不同的沉积学和地球化学代理调查过程中涉及的气候信号从北非中部和东部的EMS。合适的替代物是粘土矿物、粒度以及主要和微量元素。此外，我们要研究的物种组成和底栖有孔虫动物的微生境结构，以评估撒哈拉沙漠灰尘的海洋生态系统的EMS的施肥潜力。

Geological data and model simulations document repeated African Humid Periods during the late Quaternary. Each of them spans ca. 10 kyr and corresponds to a much shorter interval of sapropel formation in the deep Eastern Mediterranean Sea (EMS). Because only few detailed geological records are available and numerical circulation models do not draw a uniform picture, there is still a debate regarding the dynamics of the humid periods, especially the nature of the landscape evolution, the asymmetry between West and East African records, the dynamics during onset and termination of humid periods, and possible biophysical feedbacks between climate and vegetation.In our proposed study we plan to approach these open questions from a distal perspective by reconstructing the intensity and dynamics of dust fluxes from North Africa into the EMS. We will achieve this by producing high-resolution data sets from three sediment cores recovered from key positions in the EMS. The cores contain sediments of the last 130 kyr including sapropel layers S1 to S5 and the corresponding humid periods. Core GeoTü SL110 was retrieved from the Nile River discharge plume in the SE Levantine Sea, close to the coast of Israel, and should document changes in the monsoon-driven riverine sediment input. Core SL99 comes from the SW Levantine Sea, close to the North African coast off Libya. It should be primarily influenced by dust fluxes from the central and eastern Sahara, and should record the hydrological history of that region. Core SL71 comes from the Ionian Sea, SW of Crete. Our preliminary study shows that in this core we can distinguish between climatic signals from the north and the south.We want to investigate especially the interplay of solar insolation, monsoon activity, precipitation, vegetation cover, river runoff, wind erosion and aeolian transport. We are most interested in the timing of the African Humid Periods, on their gradual versus abrupt onsets and terminations and the relation between aridification/dust transport and precipitation/river discharge. To this end, we intend to apply different sedimentological and geochemical proxies for investigating processes involved in the transfer of climatic signals from the central and eastern part of North Africa to the EMS. Suitable proxies are clay minerals, grain sizes and major and trace elements. Furthermore we want to study the species composition and microhabitat structure of the benthic foraminiferal fauna in order to assess the fertilization potential of Saharan dust on the marine ecosystem of the EMS.