Quantifying the 18O/16O of Glacial Meltwater Pulses Using a Novel LA-ICPMS/IRMS Multiproxy Approach

使用新型 LA-ICPMS/IRMS 多代理方法量化冰川融水脉冲的 18O/16O

• 批准号: 1061676
• 负责人: Howard Spero
• 金额: $ 35.96万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1061676&HistoricalAwards=false
• 关键词: Quantifying; 18O; 16O; Glacial; Meltwater

The growth and decay of large ice sheets over the North American continent during the last glacial period had far reaching effects on climate and ocean circulation. Meltwater input into the oceans during deglaciation caused sea level to rise and has been invoked as a cause for rapid climate change. However, the relative volumetric contributions of individual meltwater pulses has been difficult to constrain, and often relies on assumptions about the stable isotope composition of the North American (Laurentide) ice sheet meltwater geochemistry. The fact that the ice sheets themselves had heterogeneous compositions, varying in both time and space, makes reconstruction a challenge.This research, carried out by scientists at the University of California at Davis, develops a novel technique to determine the instantaneous oxygen isotope composition of meltwater from the North American ice sheet. Measurements of both trace element (Mg/Ca and Ba/Ca) and oxygen isotope (δ18O) composition will be made on individual shells of planktonic foraminifera preserved in sediments of the Gulf of Mexico. Specific goals of the project are to: 1) refine the sample preparation and measurement protocols, 2) improve the calibration of the Ba/Ca salinity proxy, 3) test the technique by computing modern Mississippi River water using the new method, and 4) compute the oxygen isotope composition or river/meltwater during selected intervals of the deglaciation (Termination I) and Marine Isotope Stage 3. In terms of broader impacts, funding supports a female doctoral candidate and offers the opportunity for undergraduates to be exposed to state of the art analytical methods. The methods developed in the course of this work method could potentially be widely applied in paleoceanographic studies.

北美大陆上一次冰川时期大冰盖的生长和消融对气候和海洋循环产生了深远的影响。在冰川消融期间，融化的水进入海洋，导致海平面上升，并被认为是快速气候变化的原因。然而，单个融水脉冲的相对体积贡献一直很难限制，而且往往依赖于关于北美(劳伦蒂德)冰盖融水地球化学的稳定同位素组成的假设。事实上，冰盖本身具有不同的成分，在时间和空间上都不同，这给重建带来了挑战。这项由加州大学戴维斯分校的科学家开展的研究开发了一种新技术，可以确定北美冰盖融化水的瞬时氧同位素组成。将对保存在墨西哥湾沉积物中的浮游有孔虫的个别贝壳进行微量元素(镁/钙和钡/钙)和氧同位素(&amp；#948；18O)的测量。该项目的具体目标是：1)改进样品准备和测量方案，2)改进Ba/Ca盐度指标的校准，3)通过使用新方法计算现代密西西比河水来测试技术，4)计算冰川消融(终止I)和海洋同位素3阶段选定时段的氧同位素组成或河流/融水。从更广泛的影响来看，基金支持一名女性博士生，并为本科生提供接触最先进分析方法的机会。在这一工作方法过程中开发的方法可能在古海洋学研究中得到广泛应用。