Pollen record and age determinations of a profile at Cape Mamontov Klyk, Siberia

Non-glaciated Arctic lowlands in north-east Siberia were subjected to extensive landscape and environmental changes during the Late Quaternary. Coastal cliffs along the Arctic shelf seas expose terrestrial archives containing numerous palaeoenvironmental indicators (e.g., pollen, plant macro-fossils and mammal fossils) preserved in the permafrost. The presented sedimentological (grain size, magnetic susceptibility and biogeochemical parameters), cryolithological, geochronological (radiocarbon, accelerator mass spectrometry and infrared-stimulated luminescence), heavy mineral and palaeoecological records from Cape Mamontov Klyk record the environmental dynamics of an Arctic shelf lowland east of the Taymyr Peninsula, and thus, near the eastern edge of the Eurasian ice sheet, over the last 60 Ky. This region is also considered to be the westernmost part of Beringia, the non-glaciated landmass that lay between the Eurasian and the Laurentian ice caps during the Late Pleistocene. Several units and subunits of sand deposits, peat-sand alternations, ice-rich palaeocryosol sequences (Ice Complex) and peaty fillings of thermokarst depressions and valleys were presented. The recorded proxy data sets reflect cold stadial climate conditions between 60 and 50 Kya, moderate inderstadial conditions between 50 and 25 Kya and cold stadial conditions from 25 to 15 Kya. The Late Pleistocene to Holocene transition, including the Allerød warm period, the early to middle Holocene thermal optimum and the late Holocene cooling, are also recorded. Three phases of landscape dynamic (fluvial/alluvial, irregular slope run-off and thermokarst) were presented in a schematic model, and were subsequently correlated with the supraregional environmental history between the Early Weichselian and the Holocene.

西伯利亚东北部未被冰川覆盖的北极低地在晚第四纪期间经历了广泛的地貌与环境变化。北极陆架海域沿岸的海崖出露了埋藏于永久冻土中的陆地沉积记录，其中保存有大量古环境代用指标（如孢粉、植物大化石与哺乳动物化石）。本次发布的沉积物学（粒度、磁化率与生物地球化学参数）、冻土岩石学、年代学（放射性碳、加速器质谱与红外释光）、重矿物与古生态记录均采自马蒙托夫克利克角（Cape Mamontov Klyk），记录了过去6万年以来泰梅尔半岛东侧、毗邻欧亚冰盖东缘的北极陆架低地的环境动态变化。该区域同时被认为是白令陆桥区（Beringia）的最西端部分——晚更新世时期位于欧亚冰盖与劳伦冰盖之间的未冰川覆盖陆块。研究记录了多套砂质沉积单元及亚单元、泥炭-砂互层、富冰古冻土序列（冰楔复合体，Ice Complex）以及热喀斯特洼地与河谷的泥炭充填物。所记录的代用数据集反映了60至50千年前的寒冷冰期阶地气候条件、50至25千年前的温和间冰阶气候条件，以及25至15千年前的寒冷冰期阶地气候条件。晚更新世至全新世的过渡阶段，包括阿勒罗德暖期、早中全新世气候最适宜期以及晚全新世降温过程，也均被该记录覆盖。研究提出了三期地貌动态过程（河流/冲积作用、不规则坡面径流与热喀斯特作用）的概化模型，并将其与威赫塞尔冰期早期至全新世的超区域环境历史进行了关联。