Multi-proxy investigations on geological archives provide valuable information about environmental variations in the past. As opposed to single-proxy studies, the combination of several proxies can reveal more detailed information and strengthen subsequent paleoenvironmental reconstructions. However, there is still no consensus about how to deal with resulting highly dimensional datasets in a statistical manner. In many cases, the interpretations of multi-proxy datasets rely on visually matching several proxy records, which can lead to incorrect or insufficient interpretations. Here we report an innovative approach that combines the novel dimension reduction technique Uniform Manifold Approximation and Projection (UMAP) and the time series analysis R package asdetect to identify and characterize Holocene environmental phases and phase boundaries in a sediment core from Lake Chatyr Kol, southern Kyrgyzstan. Despite the fact that the Holocene climate evolution of Central Asia has been intensively studied during the last decades, knowledge about regional climate development during the Holocene and the underlying mechanisms is still relatively scarce. We particularly focus on phase transitions and differentiate between event-based shifts as opposed to gradual phase transitions. For this study, long-chain alkenones were used as a paleotemperature proxy and variations in long-chain alkyl diol distributions were ascribed to relative changes of algal input. The compound-specific stable hydrogen isotope compositions (δD) of individual n-alkanes were utilized as paleohydrological proxies, with the δD of mid-chain n-alkanes reflecting changes in the δD of the lake water and the δD of long-chain n-alkanes recording the δD of the meteoric water. We show the potential of modern analysis tools for data-driven paleoenvironmental reconstructions and advocate for their more frequent implementation in multi-proxy studies.

地质档案的多代理调查提供了有关过去环境变化的有价值的信息。与单一代理研究相反，几种代理的结合可以揭示更详细的信息并加强随后的古环境重建。但是，关于如何以统计方式处理所得的高维数据集，仍未达成共识。在许多情况下，多代理数据集的解释依赖于视觉上匹配多个代理记录的记录，这可能导致错误的解释或不足的解释。在这里，我们报告了一种创新方法，该方法结合了新颖的降维技术均匀流形近似和投影（UMAP）和时间序列分析R包检测来鉴定吉尔吉斯斯坦南部查特尔·科尔湖沉积物中的全新世环境相和相界。尽管在过去的几十年中对中亚全新世气候演变进行了深入研究，但关于全新世区域气候发展及其基本机制的知识仍然相对匮乏。我们特别关注相变，并区分基于事件的转变与逐渐的相变。在这项研究中，长链烯酮被用作古温度的代用品，长链烷基二醇分布的变化归因于藻类输入的相对变化。化合物的特定化合物的稳定氢同位素组成（δD）ñ-烷烃被用作古水文代理，中链的δD ñ烷烃反映湖水δD和长链δD的变化 ñ-烷烃记录流星水的δD。我们展示了用于数据驱动的古环境重建的现代分析工具的潜力，并提倡在多代理研究中更频繁地实施这些工具。