Deduction of Glacial-Holocene Bottom Water Temperature Changes from Epimerization Rate Changes in AMS Dated Foraminifera

从AMS测年有孔虫差向异构化速率变化推导冰川-全新世底层水温变化

• 批准号: 8812436
• 负责人: Lloyd Keigwin
• 金额: $ 7.4万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-11-01 至 1991-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8812436&HistoricalAwards=false
• 关键词: Deduction; Glacial; Holocene; Bottom; Water

Glacial-Holocene changes in bottom water temperature will be calculated by measuring changes in the rate of amino acid diagenesis (isoleucine epimerization) in radiocarbon dated, planktonic foraminifera from equatorial Atlantic, Pacific and Indian Ocean cores. The extent of epimerization in a sample is a function of the time elapsed, and the integrated thermal history, since death of the organism. By constraining the age of our samples using existing accelerator mass spectrometry (AMS) 14c dated core samples, we will obtain precise determinations of epimerization reaction rates. The temperature dependence of the reaction for individual taxa will be calibrated by laboratory heating experiments and by analysis of Holocene samples from the major ocean basins, and from marginal seas where the bottom water temperatures are elevated. The results of the study will, for the first time, provide a measurement of bottom water temperature that is independent of an analysis of the oxygen isotope record. This will contribute to an improved understanding of the 180 record, allowing us to explicitly calculate ice volume (sea level) and watermass salinity values, and to test theories calling for changes in bottom water temperature during the last glacial cycle, or for floating ice shelves in the northern and/or southern hemispheres. %%% This project will determine the change in the temperature of bottom-water in the worlds ocean from the peak of the last ice age to present. The data will be generated from the rate of amino acid diagenesis in foraminifera from sedimentary cores which have been dated by AMS carbon-14 techniques. This will be the first time glacial bottom-water temperature have been determined independently of the oxygen isotope technique, and will allow greater accuracy of the paleotemperature method. These results will be important in quantifying climatic parameters so that models of glacial climates may be refined.

冰川-全新世底层水温的变化将是 通过测量氨基酸速率的变化来计算 放射性碳年代测定的成岩作用（异亮氨酸差向异构化）， 赤道大西洋、太平洋和太平洋的浮游有孔虫 印度洋岩芯。 样品中差向异构化的程度 是经过的时间的函数， 历史，从生物体死亡开始。 通过约束 使用现有的加速器质量， 14 C测年的岩心样品，我们将获得 差向异构化反应速率的精确测定。 的 单个分类群反应的温度依赖性 将通过实验室加热实验和 分析主要海洋盆地的全新世样品，以及 从底层水温 升高。 研究结果将首次提供 测量底层水温， 独立于氧同位素记录的分析。这 将有助于更好地了解180记录， 允许我们明确计算冰的体积（海平面） 和水体盐度值，并测试理论， 最后一个月底层水温的变化 冰川循环，或在北方的浮动冰架 和/或南半球。 %%% 该项目将确定温度的变化， 世界海洋中的底层水， 冰河时代到现在 数据将从速率生成 沉积物中有孔虫的氨基酸成岩作用 用AMS碳-14技术测得的岩芯年代。 这将是第一次冰川底部水温 已经独立于氧同位素被确定 技术，并将允许更大的准确性 古地温法 这些结果将是重要的， 量化气候参数， 气候可以改善。