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

9725033国际热带木材组织对涵盖年际至千年时间尺度的高分辨率代理气候记录的研究在全球气候变化领域日益重要。其中许多替代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中的介形虫壳化石，如湖泊、泉水和湿地。介形类(微型甲壳类)的作用类似于海洋世界中的有孔虫，通过它们的生态、贝壳地球化学和生物地理分布提供关于气候和水文循环相互作用的重要信息。事实上，介形类是大陆记录中最主要的钙质微体化石。尽管目前正在进行的关于大陆记录中的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。目前还没有研究表明，通过现场和实验室校准，同位素分馏和介形虫同位素组成之间的现代关系充其量仍是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。我们建议进行野外和实验室的介形虫种类和贝壳化学的校准研究。这项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替代指标。这项实地研究将校准介形虫物种分布和壳化学(18O，(13C，镁/钙，锶/钙)，对照水化学(阳离子，阴离子，TIC，(18O，(D，DIC的13C)和气候数据)。这将包括对年内和年际变化的研究。这项基于实验室的研究将验证几种常见介形虫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。这项研究的结果将首次通过野外和实验室校准提供介形虫同位素和微量元素组成的实验验证，作为古气候分析的可量化指标。将审查和评估围绕季节性、水化学可变性、重要影响和不同水文状况的基本问题。因此，将填补古气候知识库中的一个根本空白。

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.