晚更新世以来东亚季风区多次经历千年及亚千年尺度的气候快速变化事件，从时间角度精确对比气候变化在不同沉积环境中的记录有助于理解其触发机制和传播机理。日本海深海记录是东亚古环境重建研究中的重要组成部分，然而由于14C定年技术在海洋环境中的应用具有较多限制(如海洋碳库效应等)，导致海相记录难以精确定年，极大地阻碍了海相记录与其他高分辨率古记录的精确对比。火山灰作为等时标志层能够对海相古记录进行定年，并帮助这类记录实现跨区域对比。项目选取日本海五万年以来沉积物开展精细的火山灰年代学研究。利用显微火山灰技术提取沉积物中过去被忽略的火山灰层，通过地层关联查明其精确喷发年代，借助火山灰年龄构建海洋层序高精度年代学模型，从而解决海洋钻孔14C定年难题；同时利用火山灰的等时特性实现海-陆古记录时间同步，研究气候变化事件在不同记录中的相位差异，帮助理其成因和传播。研究结果对预测未来气候变化具有重要参考价值。

East Asia has experienced rapid climate change events on millennial and sub-millennial scales since the late Pleistocene. Precise comparisons of palaeoclimatic records from different sedimentary environments facilitate our understanding of the triggering and propagation mechanisms of rapid climate changes. Deep-sea records from Sea of Japan play an important role in the reconstruction of East Asian palaeoenvironments. However, application of the 14C method in marine environment has many limitations (e.g., marine reservoir effect), which hinder the precise dating of marine records and their precise comparisons to other high-resolution records. Volcanic ash (tephra) layers, as isochronous marker horizons, can be used to date marine records and facilitate the inter-regional comparisons of such records. Therefore, this project selects the recent 50 ka sedimentary record from Sea of Japan to carry out detailed tephrochronological study. Using the cryptotephra separation techniques, we aim to extract non-visible tephra layers from the marine sediments which were not known from previous visible tephra studies. Through distal-proximal tephra correlation, we are able to unravel the precise eruptive ages of the extracted cryptotephra layers. Using this we can establish a high precision age-depth model for the marine record thus resolving the difficulties of 14C dating in marine environments. In addition, tephra isochrons can be used to synchronize disparate palaeoclimatic records, facilitating the investigation into the phase relationships of climate changes in different regions. This information would further our understanding of the cause and propagation mechanisms of rapid climate changes and help predict future climate changes.