Reconstruction of Deep-Water Temperatures in the Drake Passage Over the Last Glacial Cycle: Application of Carbonate Clumped Isotope Thermometer to Absolutely-Dated Deep-Sea Corals

末次冰期期间德雷克海峡深水温度的重建：碳酸盐簇同位素温度计在绝对测年深海珊瑚中的应用

• 批准号: 1246387
• 负责人: Weifu Guo
• 金额: $ 30.18万
• 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: 2012
• 资助国家: 美国
• 起止时间: 2012-11-01 至 2016-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1246387&HistoricalAwards=false
• 关键词: Reconstruction; Deep; Water; Temperatures; Drake

This proposed research aims to produce high resolution, precise and accurate records of deep water temperatures in the Drake Passage over the past ~40,000 years, by applying the newly developed carbonate clumped isotope thermometer to a unique collection of modern and fossil deep-sea corals, and thus advance the understanding of the role of the Southern Ocean in modulating global climate. In addition, this study will provide further evaluation on the potential of this new thermometer to derive accurate estimates of past ocean temperatures from deep-sea coral skeletons. Funding will support an early-career junior scientist and a graduate student. Despite its crucial role in modulating global climate, rates and amplitudes of environmental changes in the Southern Ocean are often difficult to constrain. In particular, the knowledge about the deep water temperatures in the Southern Ocean during the last glacial cycle is extremely limited. This results both from the lack of well-dated climate archives for the deep Southern Ocean and from the fact that most existing temperature proxies (e.g. del18O and Mg/Ca of foraminifera and corals) suffer from the biological 'vital effects'. The latter is especially problematic; it causes substantial challenges in interpreting these geochemical proxies and can lead to biases equivalent to tens of degrees in temperature estimates. Recent development of carbonate clumped isotope thermometer, holds new promises for reconstructing deep water temperatures in the Southern Ocean, since calibration studies of this thermometer in deep-sea corals suggest it is largely free of vital effects. This proposed research seeks to refine the calibration of carbonate clumped isotope thermometer in deep-sea corals at low temperatures, improve the experimental methods to obtain high precision in temperature estimates, and then apply this thermometer to a unique collection of modern and fossil deep-sea corals collected from the Drake Passage during two recent Office of Polar Programs (OPP)-funded cruises, that have already been dated by radiocarbon and U-series methods. By combining the reconstructed temperatures with the radiocarbon and U-Th ages for these deep-sea corals, this study will explore the relationships between these temperature changes and global climate changes.

这项拟议的研究旨在通过将新开发的碳酸盐凝块同位素温度计应用于独特的现代和化石深海珊瑚收藏，对德雷克海峡过去约40，000年的深水温度进行高分辨率，精确和准确的记录，从而促进对南大洋在调节全球气候中的作用的理解。此外，这项研究还将进一步评估这种新的温度计从深海珊瑚骨骼中准确估计过去海洋温度的潜力。资金将支持一名职业生涯早期的初级科学家和一名研究生。 尽管南大洋在调节全球气候方面发挥着关键作用，但其环境变化的速度和幅度往往难以控制。特别是，关于南大洋在末次冰期循环期间的深水温度的知识极其有限。这是由于缺乏南大洋深部的日期明确的气候档案，以及大多数现有的温度代用指标（如有孔虫和珊瑚的del 18 O和Mg/Ca）受到生物“生命效应”的影响。后者尤其成问题;它给解释这些地球化学代用指标带来了巨大挑战，并可能导致温度估计值出现相当于数十度的偏差。最近开发的碳酸盐凝块同位素温度计为重建南大洋深水温度带来了新的希望，因为对深海珊瑚中这种温度计的校准研究表明，它基本上没有生命效应。这项拟议中的研究旨在改进低温下深海珊瑚中碳酸盐聚集同位素温度计的校准，改进实验方法以获得高精度的温度估计，然后将该温度计应用于最近两次极地计划办公室（Office of Polar Programs）资助的巡航中从德雷克海峡收集的现代和化石深海珊瑚的独特收藏，已经用放射性碳和铀系方法测定了年代。通过结合这些深海珊瑚的放射性碳和U-Th年龄的重建温度，这项研究将探讨这些温度变化和全球气候变化之间的关系。