Sedimentary systems respond to environmental forcings in dissimilar ways over different timescales. The Lake Malawi (Nyasa) Rift is an ideal natural laboratory for evaluating the overall functioning of lacustrine source-to-sink systems on orbital or younger scales. These closed sedimentary systems exhibited high spatiotemporal climate variability, and their responses to two late Pleistocene lake-level stillstands are evaluated. The coarse-grained deposits documented a dramatic transgression from 350 to 200 m below present lake-level (BPLL) developed during an important climate transition in tropical Africa. Based on an integrated analysis of a digital elevation model and high-resolution single/multi-channel seismic profiles, catchment geomorphology has been linked with sediment delivery in the sink area. The coarse-grained deposition of each source-to-sink system is quantified through a sediment mass calculation. A modified empirically-derived ‘BQART’ predictor with a bedload equation to assess the sediment discharge is employed based on a Monte Carlo simulation, considering temperature lapse rate and topographic effects. The river discharges are estimated by specific empirical relationships that associate catchment area to various climate systems, developed using a global modern river database. The results show that the total sediment discharge increases from 7.53 to 9.50 Mt year⁻¹; likewise, the preserved coarse-grained deposits also record a significant increase in deposition rate from 350 to 200 m BPLL stage, indicating that the short length-scale source-to-sink systems are sensitive to the high-amplitude lake transgression developed from the climate shift. The volume of upstream buffered deposits may decrease within the progressively wetter climate, while the buffering degree was substantially influenced by the pre-existing landforms. Moreover, the substantial deep-water mud dispersal is not well-developed, despite the relatively higher lake-level and slightly wetter climate. This quantitative source-to-sink analysis with the modified sediment predictor yields preliminary constraints for system functioning in response to high-amplitude climate change in a closed sedimentary system.

中文翻译：

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轨道尺度气候变化驱动的高振幅湖泊水位上升的源到汇响应：以东非更新世马拉维湖（尼亚萨）裂谷为例

沉积系统在不同的时间尺度上以不同的方式响应环境强迫。马拉维湖（尼亚萨）裂谷是在轨道或更年轻的尺度上评估湖相源汇系统整体功能的理想天然实验室。这些封闭的沉积系统表现出高度的时空气候变异性，并评估了它们对两个晚更新世湖泊级静止架的响应。粗粒沉积物记录了在热带非洲重要的气候转变期间形成的从现有湖泊水位 (BPLL) 以下 350 米到 200 米的剧烈海侵。基于对数字高程模型和高分辨率单/多道地震剖面的综合分析，流域地貌已与汇区的沉积物输送相关联。每个源到汇系统的粗粒沉积通过沉积物质量计算进行量化。基于蒙特卡罗模拟，考虑到温度递减率和地形影响，采用改进的凭经验得出的“BQART”预测器，该预测器具有用于评估沉积物排放的床负荷方程。河流流量是通过特定的经验关系来估计的，这些关系将集水区与各种气候系统联系起来，使用全球现代河流数据库开发。结果表明，总泥沙排放量从 7.53 Mt 年增加到 9.50 Mt 考虑温度递减率和地形效应。河流流量是通过特定的经验关系来估计的，这些关系将集水区与各种气候系统联系起来，使用全球现代河流数据库开发。结果表明，总泥沙排放量从 7.53 Mt 年增加到 9.50 Mt 考虑温度递减率和地形效应。河流流量是通过特定的经验关系来估计的，这些关系将集水区与各种气候系统联系起来，使用全球现代河流数据库开发。结果表明，总泥沙排放量从 7.53 Mt 年增加到 9.50 Mt^-1 ; 同样，保存下来的粗粒沉积物也记录到沉积速率从 350 到 200 m BPLL 阶段显着增加，表明短尺度源汇系统对气候发展的高幅湖侵敏感转移。在逐渐湿润的气候下，上游缓冲沉积物的体积可能会减少，而缓冲程度受先前存在的地貌影响很大。此外，尽管湖水位相对较高，气候略湿润，但大量的深水泥浆扩散并不发达。这种使用修改后的沉积物预测器进行的定量源汇分析产生了系统功能的初步限制，以响应封闭沉积系统中的高幅度气候变化。