A physical record of the circumpolar circulation of the Southern Ocean - late Miocene to Pleistocene

南大洋环极环流的物理记录——晚中新世至更新世

• 批准号: 0337091
• 负责人: David Rea
• 金额: $ 13.26万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0337091&HistoricalAwards=false
• 关键词: physical; record; circumpolar; circulation; Southern

This work will increase our understanding of how deep-ocean circulation has changed with respect to important climate changes of the late Cenozoic. Today, deep waters of the three oceans blend in the Antarctic Circumpolar Current (ACC) as they are continually transported from one ocean basin to the next one east. This flow, now about 100 to 150 million cubic meters per second, is responsible for most of the heat and nutrient transport among the deep Atlantic, Indian and Pacific Oceans. The ACC also isolates Antarctica from the warmer world to the north and its surface waters provide moisture to the continent. As such, a carefully constructed history of this flow would significantly increase our understanding of late Cenozoic global change. We propose to develop a detailed physical record of the Antarctic Circumpolar Current that spans the last 9 Myr. To achieve this we will apply the methods developed in studying deep-sea drift deposits elsewhere to the drift sediments recovered by ODP Leg 178 on the Pacific margin of the Antarctic Peninsula. Data generated by the scientific party of Leg 178, along with our preliminary information, suggest that these deposits are a faithful monitor of ocean-wide events. The primary tool of our analysis will be the anisotropy of magnetic susceptibility (AMS) which is a quantitative measure of the fabric--or degree of alignment--in a sediment. We and others have shown that stronger currents result in more pronounced fabrics. Other data to be generated will include: the grain-size distribution of the terrigenous sediment component, which allows discrimination between drift-related sediments and distal turbidites; the weight percent of terrigenous sediment in each sample, and by difference in this two-component deposit, the amount of opal; the mass accumulation rate of these components; and by orienting the fabric information to the magnetic field vector recorded in the same sample, the direction of the flow. The educational impact of this work centers on the graduate student for whom this research will provide a Ph.D. thesis project, but also involves undergraduates in hands-on research.

这项工作将增加我们对深海环流如何随着新生代晚期重要气候变化而变化的理解。今天，三大洋的深层沃茨在南极绕极流（ACC）中混合，因为它们不断地从一个洋盆输送到下一个东部洋盆。这种流量现在约为每秒1亿至1.5亿立方米，负责大西洋、印度洋和太平洋深海之间的大部分热量和营养物质输送。ACC还将南极洲与北部较温暖的世界隔离开来，其表面沃茨为大陆提供水分。因此，一个精心构建的历史，这一流动将显着增加我们的理解晚新生代全球变化。我们建议开发一个详细的物理记录的南极绕极电流，跨越过去的900万年。为了实现这一目标，我们将把在其他地方研究深海漂流沉积物时开发的方法应用于ODP第178航次在南极半岛太平洋边缘回收的漂流沉积物。沿着的第178航段科学考察队所获得的数据，以及我们的初步信息，表明这些沉积物是对海洋事件的忠实监测。我们分析的主要工具将是磁化率的各向异性（AMS），这是沉积物中结构或排列程度的定量测量。我们和其他人已经表明，更强的电流导致更明显的织物。将产生的其他数据将包括：陆源沉积物成分的粒度分布，从而可以区分与漂移有关的沉积物和远端浊积岩;每个样品中陆源沉积物的重量百分比，以及根据这两种成分存款的差异，蛋白石的数量;这些成分的质量积累率;并且通过将织物信息定向到记录在同一样品中的磁场矢量，确定流动的方向。这项工作的教育影响集中在研究生身上，这项研究将为他们提供博士学位。论文项目，但也涉及动手研究的本科生。