Fluid inclusion water isotopes in speleothems using CRDS - understanding carbonate d18O responses to climate variability

流体包裹体是指矿物中含有的少量水和/或气体。它们是原始流体环境的遗迹，在合适的档案中可以提供对溶液d18O和dD值及其随时间演变的见解。特别有希望的是应用于洞穴中的流体包裹体，因为该档案提供了良好的年龄控制，并且在大多数大陆地区普遍存在。德国索尔兰（Sauerland）的洞穴生长于全新世，其碳酸盐d18O值在很大程度上遵循了这一时期的全球气候模式。然而，d18O值对气候事件的响应存在差异，特别是在8.2 ka事件和小冰期（LIA）期间。流体包裹体可以约束水d18O值，从而有助于解开8.2 ka事件和LIA期间碳酸盐d18O值差异的原因。此外，Sauerland洞穴中的流体包裹体可以用来重建全新世德国降水的同位素演化，并为自然变率及其对中欧气候的影响提供线索。我们打算将流体包裹体中定量提取水和气体的装置与用于释放水量同位素分析的吸收光谱（CRDS）系统相结合。我们申请资助CRDS系统和一个博士生来设置和校准系统，并分析绍尔兰石笋的样本。在计划研究之外，流体包裹体系统在水文和古气候方面具有广泛的潜在应用。

Fluid inclusions refer to small aliquots of water and/or gases contained inside minerals. They are relicts of the original fluid environment and in suitable archives can provide insights into the solution d18O and dD values and their evolution through time. Especially promising is an application to fluid inclusions in speleothems as this archive provides a good age control and is ubiquitous in most continental regions. Speleothems from Sauerland (Germany) grew during the Holocene and with their carbonate d18O values largely follow the global climatic patterns during this time period. d18O values, however, show discrepant responses to climatic events, in particular, during the 8.2 ka event and the Little Ice Age (LIA). Fluid inclusions can constrain the water d18O values and therefore help to disentangle the causes for the discrepant carbonate d18O values during 8.2 ka event and LIA. Furthermore, fluid inclusions in the Sauerland speleothems can be used to reconstruct the isotopic evolution of the precipitation in Germany during the Holocene and give clues for natural variability and its influence on the Central European climate. We intend to combine an apparatus for quantitative water and gas extraction from fluid inclusion with an absorption-spectroscopic (CRDS) system for isotopic analysis of the released water amount. We apply for funding for the CRDS system and a PhD student to setup and calibrate the system and for the analysis of samples from the Sauerland stalagmites. Beyond the planned study, the fluid inclusion system has a vast range of potential applications in hydrology and paleoclimate.