The normally-closed Caspian Sea is known for large changes in relative sea-level (of ∼170 m) during the late Quaternary. These transgressive/regressive events influenced the topography, sedimentation and ecosystems of a large area, of up to 1 million km². The Volga River has played an important role in the water balance of the Caspian Quaternary basins but our understanding of the temporal evolution is poorly constrained. Recent studies on the evolution of the Lower Volga have focused mainly on the subaerial sequence of loess-palaeosol series corresponding to a long-duration Caspian low stand (the so-called “Atelian regression” from ∼90 to ∼25 ka). In this study we address, for the first time, the temporal evolution of the Volga River during the late Quaternary, as recorded in the many layers of alluvial sands at the Raygorod reference section. This 50 m high outcrop contains a complicated sequence of different types of interlayered alluvium (channel and floodplain facies), a loess-palaeosol sequence with a weakly developed palaeosol, and marine sediments of the Khvalynian transgression (Chocolate Clay facies). The new chronology, based on 35 samples, is derived using optically stimulated luminescence (OSL) analysis of sand-sized quartz, with support from post-infra-red infra-red stimulated luminescence (post-IR IRSL) from K-rich feldspar grains to date the older parts of the section. The new ages identify five stages of the topography development in the northern parts of the Lower Volga: (1) an MIS 5a flood-plain in deltaic/estuary environments (>90 ka) during a high-stand of the Caspian Sea (Hyrcanian transgression); (2) a transition from deltaic/estuary conditions to a river valley with normal alluvial sedimentation and sporadic stabilization reflected in palaeosol development (80–70 ka); (3) a palaeo-Volga channel migration at elevations of 4–8 m msl during 69–62 ka, evidence of a brief increase in Caspian Sea-level and blocking of the Volga flow; (4) a subaerial stage with high-speed accumulation of loess during MIS 4 to MIS 2, containing one weakly developed palaeosol (MIS 3c) and pedocomplex of three combined palaeosols of the beginning of MIS2 (30–24 ka); (5) a rapid Khvalynian transgression, starting at the Raygorod location at ∼18.3 ka, with relatively weak marine erosion of the top 40–60 cm of loess cover, presumably because of the rapid migration of the coastline in the flat Northern Caspian Lowland.

常闭的里海以晚第四纪相对海平面（~170 m）的巨大变化而闻名。这些海侵/海退事件影响了面积达 100 万平方公里的大面积地形、沉积和生态系统². 伏尔加河在里海第四纪盆地的水平衡中发挥了重要作用，但我们对时间演化的理解却很有限。最近关于伏尔加河下游演化的研究主要集中在与里海长期低位相对应的黄土-古土壤系列的陆上序列（从~90到~25 ka的所谓“Atelian回归”）。在这项研究中，我们首次讨论了伏尔加河在第四纪晚期的时间演变，正如在 Raygorod 参考剖面的多层冲积砂中所记录的那样。这个 50 m 高的露头包含一系列复杂的不同类型的夹层冲积层（河道和洪泛平原相），一个黄土-古土壤序列，古土壤发育较弱，和Khvalynian 海侵的海洋沉积物（巧克力粘土相）。新的年表基于 35 个样品，是通过对沙粒大小的石英进行光激发发光 (OSL) 分析得出的，并得到来自富钾长石颗粒的红外后红外激发发光 (post-IR IRSL) 的支持迄今为止该部分的较旧部分。新时代确定了伏尔加河下游北部地形发展的五个阶段：（1）在里海高位（Hyrcanian 海侵）三角洲/河口环境（>90 ka）中的 MIS 5a 泛滥平原); （2）从三角洲/河口条件向河谷过渡，具有正常的冲积沉积和古土壤发育中反映的零星稳定（80-70 ka）；(3) 69-62 ka 期间海拔 4-8 m msl 的古伏尔加河道迁移，里海平面短暂上升和伏尔加河水流阻塞的证据；（4）MIS 4~MIS 2陆上黄土高速堆积阶段，包含一个弱发育的古土壤（MIS 3c）和MIS2开始（30~24 ka）的三个组合古土壤的土壤复合体；(5) 快速的Khvalynian 海侵，从Raygorod 位置~18.3 ka 开始，顶部40-60 cm 黄土覆盖层的海洋侵蚀相对较弱，可能是因为平坦的北里海低地的海岸线快速迁移。