南海北部砗磲天分辨率δ18O记录及其在古天气研究中的潜力

极端天气事件如台风、暴雨等，虽发生在较短时间尺度（小时-天-周），但通常会对生态系统和人类社会造成重大影响。利用地质生物载体，研究过去不同气候背景下极端天气事件（古天气）状态和变率，可为理解和预测极端天气事件提供科学依据。砗磲是全球最大双壳类，其致密的文石壳体通常具有天生长纹层，是优良的古天气研究载体。砗磲古天气研究目前正处于起步阶段，开发超高分辨率（小时-天-周）古天气代用指标是当前最重要的工作之一。在近期研究中，申请人等首次利用二次离子质谱（SIMS，测试分辨率10–30 μm），从南海砗磲（天纹层宽10–60 μm）中获得了一些分辨率为天的δ18O数据，并发现其有潜力开展古天气尝试研究。在此基础上，本项目拟进一步使用SIMS对南海北部现代砗磲开展天分辨率δ18O测试，结合天纹层年代学框架和器测资料，研究砗磲天分辨率δ18O的气候/天气指示意义，探讨其重建古天气变化的潜力。

Extreme weather events, such as tropical cyclones, cold/hot surges, rainstorms, usually occur on timescales of days, but nevertheless potentially cause great damage to the local socioeconomic and environmental systems. Therefore, studying extreme weather events using instrumental data and paleoweather archives to increase the understanding and prediction should be an important task of earth science. Tridacna spp., are the biggest bivalve in the world. Their hard and dense aragonite shells with clear daily growth bands have been demonstrated to be an ideal paleoweather archive in recent studies. However, the paleoweather proxies based on the daily growth layers of Tridacna spp. are still very single, which needs further development. δ18O, one of the most commonly used geochemical indices in paleoclimate research, has also been widely used for monthly paleoclimate reconstruction in coral and Tridacna spp., which usually reflect sea surface temperature (SST) and seawater δ18O. If the resolution of Tridacna spp. δ18O can be improved to day, it would be hopeful to be used for reconstructions of hot/cold surges, rainstorms, ect. However, few daily resolution δ18O record of Tridacna spp. was reported and potential controls on daily to weekly Tridacna spp. δ18O remained unclear. In this study, the modern Tridacna spp. shells with 10–60μm daily growth increments collected from the northern South China Sea, will be used for producing daily to weekly resolution δ18O records based on secondary ion mass spectrometer (SIMS) with 10–30μm spatial resolution. We will extract the weather signals from daily to weekly resolution δ18O records of modern Tridacna spp. and discuss its potential for paleoweather reconstruction.