Collaborative Research: Tracking North Atlantic Water Column Structure and Circulation Through the Late Cretaceous Using Oxygen and Neodymium Isotopes in Fish Debris

合作研究：利用鱼残骸中的氧和钕同位素追踪白垩纪晚期的北大西洋水柱结构和循环

• 批准号: 0623433
• 负责人: Kenneth MacLeod
• 金额: $ 13.45万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-15 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0623433&HistoricalAwards=false
• 关键词: Collaborative; Research; Tracking; North; Atlantic

This project will investigate circulation of intermediate and deep water masses in the Late Cretaceous North Atlantic relative to organic carbon burial and greenhouse ocean circulation. The Late Cretaceous includes the warmest conditions and the largest perturbations to global carbon cycle of the past 250 million years. Our pilot data (epsilon-Nd and d18O values in fish debris) suggest a separate and distinct, locally-sourced intermediate water mass was present in the tropical western North Atlantic throughout the Late Cretaceous except during regional to global carbon burial events, specifically, ocean anoxic event 2 and the mid-Cenomanian event. During these intervals there are dramatic shifts in epsilon-Nd that suggest enhanced bottom water mixing. The combination of evidence for 1) sinking of waters at low latitudes as a background condition and 2) more vigorous deep circulation during times of global burial of organic carbon contradict predictions of leading paradigms regarding both greenhouse oceans and ocean anoxic events. This project will test the generality of these findings through analyses of well-dated samples from a variety of sites using Ocean Drilling Program/Deep Sea Drilling Program cores. By mapping the distribution of intermediate and deep water waters as a function of position, depth, and time we will both constrain the importance of deep water in the evolution of greenhouse climates and provide empirical results against which ocean-atmosphere climate models can be compared. The project involves a new partnership between state universities and includes key participants who are members of groups underrepresented in the Earth Sciences.

本项目将调查北大西洋晚白垩世中层和深层水团的环流与有机碳埋藏和温室海洋环流的关系。晚白垩世是过去2.5亿年来全球碳循环最温暖和最大扰动的时期。我们的试点数据（ε-Nd和d18 O值的鱼碎片）表明，一个单独的和独特的，本地来源的中间水团是存在于整个晚白垩世在热带西北大西洋，除了在区域性的全球碳埋葬事件，特别是海洋缺氧事件2和中塞诺曼事件。在这些时间间隔有显着的变化，ε-钕，这表明增强底层水混合。1）低纬度沃茨下沉作为背景条件，2）有机碳全球埋藏期间更活跃的深环流的证据相结合，与温室海洋和海洋缺氧事件的主要范式的预测相矛盾。该项目将通过使用大洋钻探计划/深海钻探计划岩心分析来自不同地点的年代测定良好的样本，检验这些发现的普遍性。通过绘制作为位置、深度和时间的函数的中层和深层沃茨的分布图，我们将限制深层水在温室气候演变中的重要性，并提供可与海洋-大气气候模型进行比较的经验结果。该项目涉及州立大学之间的新伙伴关系，并包括地球科学中代表性不足的团体成员的主要参与者。