Fossil diatoms and litho-stratigraphic changes in the Guern El Louläilet depressions, NW of the Great Western Erg, Algeria, were analysed to infer paleoenvironmental changes in the northern Algerian Sahara during the Early and Middle Holocene. Analysis was based on calcareous diatomite collected from four outcrops within the depressions. The diatom flora consists of brackish and epiphytic taxa, such as Epithemia argus, with percentages of some freshwater and planktonic species, mainly Cyclotella distinguenda. Results provide evidence for two Holocene lacustrine episodes related to the African Humid Period. The first episode (Early to Middle Holocene) was characterized by abrupt development of shallow-water conditions, with extensive littoral zones and evaporative periods that coincided with high salt concentrations in warm, alkaline water (swampy conditions). A second episode (Middle to Late Holocene?), with brackish water and alkaline conditions, coincided with a decline in lake water level that is attributed to drier conditions. Our findings are consistent with those of other studies from the area and demonstrate similar environmental changes occurred after 9300 cal yr BP at sites within the region. The main drivers of the African Humid Period were the northward shift of the Intertropical Convergence Zone (ITCZ) and expansion of summer monsoonal rains. Our study sites were located in the northern Sahara, where variations in the position of the Intertropical Convergence Zone (ITCZ) did not affect rainfall. Early and Middle Holocene climate fluctuations detected in this study may have been caused by intensification of winter precipitation in the south-central Mediterranean and its penetration southward.

分析了阿尔及利亚Great Western Erg西北Guern El Louläilet凹陷的化石硅藻和岩石地层变化，以推断阿尔及利亚北部撒哈拉沙漠在全新世早期和中期的古环境变化。分析基于从洼地内的四个露头收集的钙质硅藻土。硅藻植物群由咸水和附生类群组成，例如Epithemia argus，以及一些淡水和浮游物种的百分比，主要是Cyclotella distinguenda. 结果为与非洲潮湿时期有关的两次全新世湖泊事件提供了证据。第一个事件（全新世早期至中全新世）的特点是浅水条件的突然发展，具有广泛的沿海地区和蒸发期，与温暖的碱性水（沼泽条件）中的高盐浓度相吻合。第二个事件（全新世中到晚期？），在微咸水和碱性条件下，恰逢湖水位下降，这是由于更干燥的条件。我们的研究结果与该地区的其他研究结果一致，并证明在该地区内的地点 9300 cal yr BP 之后发生了类似的环境变化。非洲湿润期的主要驱动因素是热带辐合带（ITCZ）的北移和夏季季风降雨的扩大。我们的研究地点位于撒哈拉沙漠北部，热带辐合带（ITCZ）位置的变化不会影响降雨。本研究中检测到的全新世早期和中期的气候波动可能是由于地中海中南部冬季降水的加强及其向南的渗透造成的。