COLLABORATIVE RESEARCH: IPY: Testing the Polar Gateway Hypothesis: An Integrated Record of Drake Passage Opening & Antarctic Glaciation

该项目研究了德雷克航道的开放与南极冰盖形成的关系。它的目标是回答这样一个问题：是什么推动了3400万年前从温室到冰库世界的转变？是南极洲与南美洲分离造成的南大洋环流变化，还是大气二氧化碳含量减少等全球性影响？这项研究通过在南美洲和南极洲的实地考察以及海洋钻探计划以前收集的海洋沉积物岩心的新工作，限制了事件和时间。它还涉及一个广泛的、多学科的分析项目。沉积物及其来源的成分分析将与(U-Th)/He、裂变径迹和Ar-Ar热年代学相结合，以限制德雷克海峡周围大陆地壳的抬升和运动。对海洋沉积物岩心中发现的化石鱼牙的放射性同位素研究将用于追踪太平洋海水进入大西洋的情况。对有孔虫的氧同位素和微量金属测量将提供关于冰量变化的时间和幅度的更多信息。更广泛的影响包括研究生和本科教育；通过博物馆展品和演示向普通公众宣传，以及与阿根廷、乌克兰、英国和德国的科学家进行国际合作。该项目由美国国家科学基金会的国际极地年(IPY)研究重点领域“了解极地地区的环境变化”支持。该项目也是国际地球年板块和栅门倡议(国际地球年项目#77)的一个重要组成部分，其重点是确定构造门户在极地环境变化中的作用。

This project studies the relationship between opening of the Drake Passage and formation of the Antarctic ice sheet. Its goal is to answer the question: What drove the transition from a greenhouse to icehouse world thirty-four million years ago? Was it changes in circulation of the Southern Ocean caused by the separation of Antarctica from South America or was it a global effect such as decreasing atmospheric CO2 content? This study constrains the events and timing through fieldwork in South America and Antarctica and new work on marine sediment cores previously collected by the Ocean Drilling Program. It also involves an extensive, multidisciplinary analytical program. Compositional analyses of sediments and their sources will be combined with (U-Th)/He, fission-track, and Ar-Ar thermochronometry to constrain uplift and motion of the continental crust bounding the Drake Passage. Radiogenic isotope studies of fossil fish teeth found in marine sediment cores will be used to trace penetration of Pacific seawater into the Atlantic. Oxygen isotope and trace metal measurements on foraminifera will provide additional information on the timing and magnitude of ice volume changes. The broader impacts include graduate and undergraduate education; outreach to the general public through museum exhibits and presentations, and international collaboration with scientists from Argentina, Ukraine, UK and Germany. The project is supported under NSF's International Polar Year (IPY) research emphasis area on "Understanding Environmental Change in Polar Regions". This project is also a key component of the IPY Plates & Gates initiative (IPY Project #77), focused on determining the role of tectonic gateways in instigating polar environmental change.