Collaborative Research: Integrated Geochronology and Paleomagnetism of Neoarchean-Paleoproterozoic Dikes in Wyoming, A Keystone of North American Cratons

合作研究：怀俄明州新太古代-古元古代岩脉的综合地质年代学和古地磁学，北美克拉通的基石

• 批准号: 1019739
• 负责人: David Evans
• 金额: $ 23.83万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1019739&HistoricalAwards=false
• 关键词: Collaborative; Research; Integrated; Geochronology; Paleomagnetism

Supercontinents arise on the Earth when the continents cluster together, typically on one side of the Earth, as a result of multiple tectonic collisions. The past existence of supercontinents is of great interest to the tectonics scientific community, and society in general, for example for the tracing of mineral deposits. The continents today are fragments of the Pangean supercontinent, which existed during the Mesozoic age of the dinosaurs. Several lines of evidence suggest the existence of even earlier supercontinents, the subject of this study. These researchers aim to reconstruct the arrangement of continental pieces between 2.7 and 2.1 billion years ago, to determine whether ancient supercontinent cycles occurred at that time. The research will be carried out in all the major mountain ranges of Wyoming, over two summer field seasons of rock sample collection by the two principal investigators and their graduate and undergraduate students. In addition, the methods and data will be incorporated into scientific outreach programs aimed at ninth-grade inner-city students. Finally, the results will be illustrated in a computer animation made available to the general public as an educational resource. The study focuses on Wyoming, one of the cratons of North America that currently is least well known in terms of its changing positions through the Neoarchean-Paleoproterozoic interval. The researchers will be examining drift histories, conjugate margins, and cratonic chronologies for purposes of supercontinental reconstruction. In many regards, Wyoming is a central keystone in the arrangement of North American cratons during the Neoarchean-Paleoproterozoic eras. The research will entail two complementary methods: geochronology using several well established and precise isotopic methods, and paleomagnetism of rock and mineral samples that contain magnetic domains that are particularly resistant to resetting. The combination of these analyses provides a powerful tracking method for the analysis of supercontinent cycles. These measurements of time and space will be applied to dike rocks from the ancient roots of now-eroded lava plains in Wyoming. The dikes are ideal targets for the close integration of the two research methods, as indicated by preliminary data. Such data have generated much excitement that refined apparent polar wander paths from this study may result in a re-evaluation of Neoarchean-Paleoproterozoic supercontinental assembly.

当大陆由于多次构造碰撞而聚集在一起（通常位于地球的一侧）时，地球上就会出现超级大陆。 超大陆过去的存在引起了构造科学界和整个社会的极大兴趣，例如对矿藏的追踪。 今天的大陆是泛古大陆超大陆的碎片，它存在于恐龙的中生代时代。 一些证据表明甚至更早的超级大陆的存在，这也是本研究的主题。 这些研究人员的目标是重建2.7至21亿年前大陆碎片的排列，以确定当时是否发生了古代超大陆旋回。 这项研究将在怀俄明州的所有主要山脉中进行，由两位主要研究人员及其研究生和本科生在两个夏季实地采集岩石样本。 此外，这些方法和数据将被纳入针对九年级内城区学生的科学推广计划。 最后，结果将通过计算机动画进行说明，作为教育资源提供给公众。 这项研究的重点是怀俄明州，这是北美克拉通之一，目前人们对它在新太古代-古元古代时期位置变化的了解最少。 研究人员将研究漂移历史、共轭边缘和克拉通年代学，以进行超大陆重建。 在许多方面，怀俄明州是新太古代-古元古代时期北美克拉通排列的中心基石。 该研究将需要两种互补的方法：使用几种成熟且精确的同位素方法的地质年代学，以及含有特别难以重置的磁域的岩石和矿物样本的古地磁学。 这些分析的结合为超大陆旋回的分析提供了强大的跟踪方法。 这些时间和空间的测量将应用于怀俄明州现已被侵蚀的熔岩平原的古老根源的岩脉岩石。 初步数据表明，堤坝是两种研究方法紧密结合的理想目标。 这些数据引起了极大的兴奋，因为这项研究中完善的明显极地漂移路径可能会导致对新太古代-古元古代超大陆组合的重新评估。