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

该项目研究德雷克海峡的开放与南极冰盖形成之间的关系。它的目标是回答这个问题：是什么推动了3400万年前从温室世界到冰库世界的转变？是南极洲从南美洲分离造成南大洋环流的变化，还是大气中二氧化碳含量减少等全球效应？这项研究通过在南美洲和南极洲的实地考察以及对海洋钻探计划以前收集的海洋沉积物岩心的新工作来限制事件和时间。它还涉及广泛的多学科分析计划。沉积物及其来源的成分分析将结合（U-Th）/He，裂变径迹，和Ar-Ar热年代学，以约束隆起和运动的大陆地壳边界德雷克通道。对海洋沉积物岩心中发现的鱼牙齿化石进行放射性同位素研究，将用于追踪太平洋海水渗入大西洋的情况。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生教育;通过博物馆展览和介绍向公众宣传，以及与来自阿根廷、乌克兰、英国和德国的科学家进行国际合作。该项目得到了NSF国际极地年（IPY）研究重点领域“了解极地地区的环境变化”的支持。该项目也是IPY Plates Gates倡议（IPY项目#77）的关键组成部分，重点是确定构造网关在引发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.