Assessing the Fidelity of Foraminiferal Mg/Ca- d18O to Estimate Seawater d18Or: A Multispecies Calibration-Validation Study

该项目将根据（亚热带）太平洋、大西洋和西北非洲边缘三个经向芯顶样带观测到的海水d18O梯度，对浮游有孔虫中Mg/Ca和d18O的配对分析得出的壳源d18O海水估定值进行校准和验证。此外，我们将利用最近在葡萄牙和西北非洲边缘采集的浮游生物拖曳和d18o海水地表水样本进行现场d18o海水校准。该研究将验证他在一系列58个岩心样品中观察到的“过量Mg/Ca”及其与盐度的明显联系的假设，该假设可以在更大的（亚）热带海洋区域内分离和量化。本研究还将研究与“过量Mg/Ca”端元样品相关的有孔虫壳形态、重量和壳Mg/Ca异质性的系统性变化。该项目的“更广泛的影响”部分包括对博士生的支持，对本科生的参与和指导，以及对许多正在进行的古海洋学研究项目的基本组成部分——转型级问题的研究。

This project will calibrate and validate shell-derived d18Oseawater estimates that have been derived from paired analyses of Mg/Ca and d18O in planktonic foraminifera against observed d18Oseawater gradients for three meridional coretop transects in the (sub)tropical Pacific, Atlantic, and NW African margin. In addition, an in situ d18Oseawater calibration will be conducted using plankton tow and d18Oseawater surface water samples collected during a recent coring cruise off the Portuguese and NW African margins. The research will test the hypothesis that the "excess Mg/Ca" that he has observed in a series of 58 coretop samples, and its apparent link to salinity, can be isolated and quantified over a larger (sub)tropical ocean domain. This research will also examine systematic changes in foraminifera shell morphology, weight, and shell Mg/Ca heterogeneity associated with "excess Mg/Ca" endmember samples. The Broader Impacts component of this project include support of a PhD student, involvement and mentoring of undergraduate students in elements of the research, and the study of a transformative-level problem that is a fundamental component of many ongoing paleoceanographic research programs.