Reconstruction of a paleo-lakesystem at UNESCO World Heritage Site Tsodilo Hills, Kalahari, Botswana: MIS3 and MIS2 ecosystem dynamics, climate, weather and environmental variations derived from sedimentation processes and bio-indicators

天然永久湖泊最近在喀拉哈里是一个例外。地质和降水模式阻碍了它们的长期存在。然而，在晚更新世和全新世期间，大型湖泊横跨了近代半干旱的卡拉哈里盆地的相当大一部分地区。古湖泊表明，在不同的气候条件下，地下水位要高得多。一个突出的例子是位于博茨瓦纳西北部奥卡万戈三角洲盆地内的前佐迪洛湖。相应的小英塞尔贝格链构成了一个约30平方公里宽的盆地，东部是含化石的碳酸盐湖。茨迪洛是世界上岩石艺术密度最高的地方之一(在不到10平方公里的面积上有4500幅岩画)，被称为“沙漠卢浮宫”，并于2001年被联合国教科文组织列入世界文化遗产名录。人类活动和环境变化被记录在山里和周围。之前对主要是英国研究人员的调查显示，从大约40000年前到最后一次冰川时代结束，在大约一千年的时间片段中，至少存在一个周期性的大湖。很可能这个湖为石器时代的猎人和采集者提供了生计。湖泊化石提供了水质和沉积模式变化的证据。到目前为止，既没有重建前湖的最大范围，也没有重建导致长期存在的水文气候条件。该项目的目的是对湖泊生态系统动态及其附近地区以及负责任的水文气候先决条件进行“整体”重建。因此，地貌分析和沉积物的地球化学/物理性质将使重建过程(如径流、沙丘移动等)成为可能。影响着以前的风景。因此，例如，应用于高分辨率粒度分布的统计算法将揭示环境并量化运输过程，而多变量地球化学/矿物学数据分析将提供有关水收支的信息。腹足类贝壳的同位素数据应揭示降水的季节性信息。后者可能代表了南部非洲以前者为主的大气环流格局。化石将提供有关该湖水温、水深和营养含量的进一步信息。这些信息将使我们能够估计湖泊提供的资源和给人们带来的风险(例如，黑热病)。如果化石花粉在某些时间段得到充分保存，古植被的重建将提供温度和降水变化的估计，以及可捕猎野生动物的多样性和密度的推导。

Natural permanent lakes are recently an exception in the Kalahari. The geology and precipitation patterns inhibit a long lasting existence. However, during Late Pleistocene and Holocene time large lakes spanned a considerable part of the recent semi-arid Kalahari basin. The palaeolakes indicate a much higher groundwater level under different climate conditions.An outstanding example is the former Tsodilo lake in northwestern Botswana within the basin of the Okavango Delta. The correspondent small inselberg chain frames a ca. 30 km2 wide basin with fossil-bearing lake carbonates to the east. With one of the highest concentrations of rock art in the world (4500 rock paintings over an area of less than 10 km2), Tsodilo has been called the 'Louvre of the Desert' and inscribed in the list of UNESCO World Heritage Cultural Sites in 2001. Human activities and environmental change are documented in and around the hills. Prior investigations of mostly British researchers revealed the existence of an at least periodically extensive lake during time slices of some thousand years since ca. 40000 years ago until the end of the last glacial time. Likely this lake provided the livelihood for the stone-age hunters and gatherers. Lacustrine fossils provide evidence of changing water quality and sedimentation patterns. So far neither the maximum extents of the former lake nor the hydro-climate conditions responsible for long-term existence have been reconstructed. The aim of this project is a “holistic” reconstruction of the lake ecosystem dynamics and its vicinity as well as the responsible hydro-climatic preconditions. Hereby, geomorphological analyses and the geochemical/physical properties of the sediments will enable a reconstruction of processes (e.g. run-off, dune movement, etc.) affecting the former landscape. Therefore, e.g. statistical algorithms applied on high-resolution grainsize distributions shall unravel settings and quantify transport processes while multivariate geochemical/mineralogical data analyses will provide information about the water budget. Isotope data from gastropod shells shall reveal information about the seasonality of precipitation. The latter may indicate former predominant atmospheric circulation pattern in southern Africa. Fossils will provide further information about water temperature, depth and nutrition content of the lake. This information will enable us to estimate the resources provided by the lake and the risks (e.g. bilharziosis) for the people. In case of sufficient preservation of fossil pollen during certain time slices, the reconstruction of palaeo-vegetation will provide an estimation of temperature and precipitation changes as well as a derivation of diversity and density of huntable wildlife.