ESH - COLLABORATIVE RESEARCH: Continental Ostracode Assemblages & Shell Geochemistry: Calibrating a Tool for Paleoclimatic and Paleohydrologic Reconstruction

9725033 Ito覆盖年际到千年时间尺度的高分辨率代用气候记录研究在全球气候变化领域日益重要。许多这些代用气候记录包括同位素和微量元素地球化学数据，这些数据来自大陆沉积物（如湖泊、泉水和湿地）中的化石介形虫壳。介形类（微观甲壳类）在海洋世界中扮演着与有孔虫类似的角色，通过它们的生态学、壳的地球化学和生物地理分布，提供有关气候和水文循环相互作用性质的重要信息。实际上，介形虫是大陆记录中主要的钙质微化石。尽管目前对大陆记录中氧同位素和介形虫壳地球化学的研究越来越多，但在知识基础上仍有很大的差距。目前没有任何研究可以通过实地和实验室校准提供同位素分馏和介形虫同位素组成之间的现代关系充其量只能作为过去条件的定性指标。依赖介形虫同位素信息的高分辨率大陆气候记录目前还没有量化的解释依据。我们建议对介形虫种类和外壳化学进行实地和实验室校准研究。本研究的重点是介形类的现代分布及其同位素和微量元素特征，目的是发展它们作为过去地球系统过程的代理指标。野外研究将根据水化学(阳离子、阴离子、TIC、DIC的(18O、（D)、（13C））和气候数据校准介形虫物种分布和壳化学(（18O、（13C）、Mg/Ca、Sr/Ca）。这将包括对年内和年际变化的研究。实验室研究将验证几种常见介形类的氧同位素和微量元素分馏行为作为水化学和温度的函数。本研究结果将首次通过野外和实验室校准，为介形类同位素和微量元素组成作为古气候分析的可量化指标提供实验验证。将审查和评估围绕季节性、水化学变异性、重要影响和不同水文制度的基本问题。因此，古气候知识库的一个根本空白将被填补。

9725033 Ito The study of high-resolution proxy climate records covering interannual through millennial time scales is growing importance in the field of global climate change. Many of these proxy climate records include isotopic and trace-element geochemical data derived from fossil ostracode shells in continental deposits, such as lakes, springs, and wetlands. Ostracodes (microscopic crustaceans) play a role similar to that of foraminifera in the marine world by providing vital information about the interactive nature of climate and the hydrologic cycle through their ecology, shell geochemistry, and biogeographical distribution. In fact, ostracodes are the primary calcareous microfossils in continental records. Despite the increasing amount of research presently underway involving oxygen isotopes and ostracode shell geochemistry in continental records, there is significant gap in the knowledge base. There are no existing studies available that provide, through both field and laboratory calibration, the modern relationship between isotope fractionation and ostracode isotopic composition will remain at best a qualitative indicator of past conditions. The high resolution continental climate records that rely on ostracode isotopic information have at present no quantified basis for interpretation. We propose to conduct both field and laboratory calibration studies of ostracode species and shell chemistry. This research focuses on modern distributions of ostracodes and their isotopic and trace-element signatures, with the purpose of developing them as proxy indicators for past Earth system processes. The field-based study will calibrate ostracode species distributions and shell chemistry ((18O, (13C, Mg/Ca, Sr/Ca), against hydrochemistry (cation, anion, TIC, (18O, (D, (13C of DIC) and climate data. This will include a study of intra-and inter-annual variation. The laboratory-based study will verify the oxygen-isotope and trace element fractionation behavior of several common speci es of ostracodes as a function of hydrochemistry and temperature. The results of this study will provide, for the first time, experimental verification through both field and laboratory calibration, of ostracode isotopic and trace-element composition as a quantifiable indicator for paleoclimate analysis . Basic issues revolving around seasonality, hydrochemical variability, vital effects, and different hydrologic regimes will have been examined and assessed. A fundamental gap in the paleoclimate knowledge base will thus be filled.