Geomorphological and environmental responses to rapid hydrological changes in the Atlas Mountains (Morocco) during the last 30,000 years

西地中海和北非沙漠边缘是全球变暖的热点，可能包括热应力增加、降水减少和干旱更频繁发生。全新世和末次冰期档案显示了西地中海水文气候的百年至千年尺度变化，但测年不准确，所调查参数的敏感但不同的环境响应机制，以及时间分辨率不足导致许多不确定性。我们项目的主要目的是发展对西地中海-撒哈拉过渡地区环境敏感性和气候变化反应的理解。后续项目将扩展全新世之后的古水文学、古生态学和沙尘动力学知识，包括晚冰期和末次盛冰期（LGM）。我们的目标是恢复过去30 ka的连续且分辨率高的湖相序列。我们将提高对全新世快速气候变化（如LIA， 4.2和8.2 ka），全新世-晚冰期转变和LGM冷却事件在百年至千年时间尺度上的突然环境响应的理解。从半湿润的东北部到半干旱的西南部，我们将建立一个空间重点在阿特拉斯中高山区沙漠边缘。作为沙漠边缘地带，该地区对降水变化高度敏感，这反映在环境系统的动力学上。我们将首次在百年尺度分辨率下应用水文气候梯度方法和相同的多代理技术套件。我们的目标是：1 .沿着水文气候梯度检索新的湖泊沉积物岩心并确定其年代。我们将重点关注两个湖泊：位于半湿润的中阿特拉斯的西迪阿里湖和位于半干旱的高阿特拉斯的提沙湖。我们将应用210Pb定年、14C花粉和大化石定年、发光定年技术和贝叶斯年龄模型。O2：限制过去的降雨和蒸发机制。我们将利用生物（介形虫、水生花粉）和生物地球化学参数（包括介形虫的TOC、碳酸盐和δ13C/δ18O）来确定湖泊水位和水文气候指标。O3：量化撒哈拉沙尘供应的过去变化。我们将应用晶粒尺寸端元模型，元素和痕量同位素分析。O4：记录流域尺度对快速气候变化的响应（植被、火灾、侵蚀）。我们将通过开发新的花粉和颗粒木炭记录来限制植物有效水分和区域温度的变化。硅碎屑参数将被用作土壤侵蚀的代用指标。O5：首次采用水文气候梯度法。我们将使用多代理统计来检测北撒哈拉沙漠边缘环境和风成响应的时空变异性。

The Western Mediterranean and the North African desert margin are hotspots of global warming that is likely to include increased heat stress, reduced precipitation and more frequent occurrence of droughts. Holocene and Last Glacial archives indicate centennial to millennial-scale changes of the Western Mediterranean hydro-climate, although dating inaccuracies, sensitive but different environmental response mechanisms of investigated parameters, and insufficient chronological resolution lead to many uncertainties.The major aim of our project is to develop the understanding of environmental sensitivities and responses to climatic variability in the zone of the Western Mediterranean-Saharan transition. The follow-up project will extend knowledge of palaeohydrology, palaeoecology and dust dynamics beyond the Holocene, including the Late Glacial and Last Glacial Maximum (LGM). We aim to recover continuous and well-resolved lacustrine sequences spanning the last 30 ka. We will improve understanding of abrupt environmental responses during Holocene Rapid Climate Changes (e.g. LIA, 4.2 and 8.2 ka), the Holocene-Late Glacial transition and LGM cooling events at centennial to millennial time-scales.We will establish a spatial focus on the Middle to High Atlas mountainous desert margin from the sub-humid Northeast to the semiarid Southwest. As a desert margin this zone is highly sensitive to precipitation changes as reflected in the dynamics of environmental systems. For the first time, we will apply a hydro-climatic gradient approach with an identical suite of multi-proxy techniques at centennial-scale resolution. Our objectives are:O1: to retrieve and date new lake sediment cores along the hydro-climatic gradient. We will focus on two lakes: Sidi Ali in the sub-humid Middle Atlas and Tislit in the semiarid High Atlas. We will apply 210Pb dating, 14C pollen and macrofossil dating, luminescence dating techniques and Bayesian age modelling.O2: to constrain past rainfall and evaporation regimes. We will identify lake level and hydro-climatic proxies using biological (ostracods, aquatic pollen) and biogeochemical parameters including TOC, carbonates and δ13C/δ18O on ostracods.O3: to quantify past variability in Saharan dust supply. We will apply grain size end-member modelling, element and trace isotopes analyses.O4: to document catchment-scale responses (vegetation, fire, erosion) to rapid climate changes. We will constrain shifts in plant available moisture and regional temperature through the development of new pollen and particulate charcoal records. Silici-clastic parameters will be used as proxies for soil erosion.O5: to apply for the first time a hydro-climatic gradient approach. We will use multi-proxy statistics for the detection of temporal and spatial variability in environmental and aeolian responses along the North Saharan desert margin.