Collaborative Research: Isotopic, Geochronologic, and Tectonic Character of the Western Piedmont, Virginia - Implications for the Closing of Iapetus

合作研究：弗吉尼亚州西皮埃蒙特的同位素、年代学和构造特征——对土卫八闭合的影响

• 批准号: 1048476
• 负责人: James Hibbard
• 金额: $ 27.26万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-15 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1048476&HistoricalAwards=false
• 关键词: Collaborative; Research; Isotopic; Geochronologic; Tectonic

The Iapetus Ocean is a first-order early Paleozoic oceanic tract that separated eastern North America from peri-Gondwanan crustal blocks. Its closure, which juxtaposed North America with these Gond¬wan¬an elements in the Appalachians, imposed new circulation regimes upon the global hydrosphere and atmosphere and it was a major step toward the eventual amal¬gamation of the supercontinent of Pangea. Despite the importance of Iapetus in the global evolution of the Paleozoic, little is known about the timing and nature of its closure, mainly because the original interface between North American and Gondwanan elements, the main Iapetan suture, is unrecognized in the U.S. Appalachians. On the basis of regional geological relationships and scant isotopic data, it is hypothesized that the Chopawamsic fault in central Virginia represents the main Iapetan suture in the US Appalachians. This project is testing this hypothesis by inte¬grating the results of Nd- and Pb- isotopic studies of magmatic rocks on either side of the fault; by a U-Pb zircon geochron¬ologic study of detrital zircon populations from either side of, and in strata lying above, the fault; by using high resolution U-Pb geochronology on selected magmatic units, and by a kinematic and geochronologic analysis of the fault. This study is a collaborative effort between researchers at North Carolina State University and Texas A&M University.Appalachian geology governs resources (mineral, water) for, and influences the wellbeing (seismic hazards) of, the densest human population in North America; logically, a basic understanding of the bedrock geology is essential to further development and sustainability in the region. Results of this study will also take multiple paths into the broader domains of education and outreach. The project partially supports eight students, including two females. The principal investigators are actively recruiting incoming freshman from urban high schools and from minority groups to work on this project. Texas A&M students involved in the project are encouraged to volunteer and participate in established outreach functions with the Brazos Valley Museum of Natural History. Graduate students intend to present their findings at both professional meetings and at meetings of the Virginia Association of Science Teachers, and disseminate results through the Virginia Science Standards Institute. Once significant results are available, project personnel will lead the Virginia Field Conference, an annual field trip that caters to a broad array of participants. In addition, the involvement of Canadian collaborators and a South African MS candidate adds an international component to the project. Scientific results that derive from the project will be disseminated via presentations at professional geoscience meetings and the peer-reviewed scientific literature.

土卫八洋（Iapetus Ocean）是一个一阶的早古生代洋域，它将北美洲东部与冈瓦纳地壳块体分隔开来。它的关闭，使北美与阿巴拉契亚山脉中的这些冈瓦纳元素并列，对全球水圈和大气施加了新的环流制度，这是朝着最终融合泛古陆的方向迈出的重要一步。尽管土卫八在全球古生代演化中的重要性，但人们对其闭合的时间和性质知之甚少，主要是因为北美和冈瓦纳元素之间的原始界面，主要的土卫八缝合线，在美国阿巴拉契亚山脉中未被识别。区域地质关系和同位素数据不足的基础上，它被假设为Chopawamsic断层在弗吉尼亚州中部的主要Iapetan缝合线在美国阿巴拉契亚山脉。该项目通过整合断层两侧岩浆岩的Nd和Pb同位素研究结果、断层两侧和断层上方地层中碎屑锆石群的U-Pb锆石地质年代学研究、对选定的岩浆单元使用高分辨率U-Pb地质年代学以及断层的运动学和地质年代学分析来验证这一假设。这项研究是在北卡罗来纳州州立大学和得克萨斯州农工大学的研究人员之间的合作努力。阿巴拉契亚地质管理资源（矿物，水），并影响福祉（地震灾害），在北美的人口，从逻辑上讲，基岩地质的基本了解是必不可少的，以进一步发展和可持续发展的地区。这项研究的结果还将采取多种途径进入更广泛的教育和外联领域。该项目为8名学生提供部分支助，其中包括2名女生。主要研究人员正在积极招募来自城市高中和少数民族的新生参与这个项目。参与该项目的德克萨斯州A M学生被鼓励自愿参加并参加巴西谷自然历史博物馆的既定外展活动。研究生打算在专业会议和弗吉尼亚科学教师协会的会议上展示他们的研究结果，并通过弗吉尼亚科学标准研究所传播结果。一旦取得重大成果，项目人员将领导弗吉尼亚实地会议，这是一次每年一度的实地考察，吸引了广泛的参与者。此外，加拿大合作者和一名南非硕士候选人的参与为该项目增加了一个国际组成部分。该项目的科学成果将通过在专业地球科学会议上的介绍和同行审查的科学文献传播。