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: 0623393
• 负责人: Ellen Martin
• 金额: $ 15.31万
• 依托单位: University of Florida
• 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 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0623393&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.

该项目将调查晚白垩世北大西洋中层和深层水团的循环与有机碳埋藏和温室海洋循环的关系。白垩纪晚期是过去 2.5 亿年来最温暖的气候条件和对全球碳循环最大的扰动。我们的试点数据（鱼类残渣中的 epsilon-Nd 和 d18O 值）表明，在整个白垩纪晚期，除了区域到全球碳埋藏事件（特别是海洋）期间，北大西洋热带西部地区存在一个独立且独特的、源自当地的中间水团。缺氧事件2和塞诺曼阶中期事件。在这些间隔期间，ε-Nd 发生显着变化，表明底层水混合增强。 1）低纬度水域下沉作为背景条件和 2）在全球有机碳埋藏期间更活跃的深层环流证据相结合，与有关温室海洋和海洋缺氧事件的主要范式的预测相矛盾。该项目将通过使用海洋钻探计划/深海钻探计划岩心对来自多个地点的过时样本进行分析来测试这些发现的普遍性。通过将中层水和深水的分布绘制为位置、深度和时间的函数，我们将限制深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合作伙伴关系，主要参与者都是地球科学领域代表性不足的群体的成员。