Collaborative Research: Laurentian and Non-Laurentian (Baltican) Components of Terranes in NW Washington?

合作研究：华盛顿西北部地体的劳伦系和非劳伦系（波罗的海）成分？

• 批准号: 1242939
• 负责人: George Gehrels
• 金额: $ 6.3万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1242939&HistoricalAwards=false
• 关键词: Collaborative; Research; Laurentian; Non; Baltican

Growth of the ancient North American continent (Laurentia) along its western margin in Paleozoic times occurred by addition of materials of both local and exotic origins: a sedimentary apron derived from erosion of the western flank of the continent (the miogeocline), and also a complex of accreted terranes displaced by plate tectonics from other parts of the globe and faulted into the continent. Research of this study will examine the history of the accreted Chilliwack terrane in northwest Washington about which preliminary studies suggest that at least parts came from northwestern Europe. A primary tool in our work is acquisition of U-Th-Pb ages of zircon grains in igneous and sedimentary rocks. Preliminary data from igneous rocks in the Chilliwack terrane yield ages not known in western North America, but common in ancient Scandinavia (Baltica). In sedimentary rocks, age distributions of zircons are in some rocks similar to North America and in other rocks point to an exotic (European or other) homeland. Additional zircon ages will clarify these possible correlations. Further Hf isotopic data from zircons will be used to test possible derivation of parts of the Chilliwack terrane from a primitive oceanic island arc, specifically the early Paleozoic Alexander arc terrane accreted in southeast Alaska, as opposed to evolved continental crust (Laurentian or other). Field mapping of rock units will evaluate the genetic and structural relationship among parts of the Chilliwack terrane that have North American vs. exotic affinities. The fundamental goal of the project is basic knowledge of mechanisms of plate tectonics and processes of formation of an active continental margin.The research plan is designed to address the scientific issue described above, and also to enhance the education and training of students and elevate interest and understanding of earth history of the Pacific Northwest in the general public. Project funds will support undergraduate students as assistants in the field and laboratory, and pay for students to attend a professional meeting. Student research on the project will likely form the basis of senior theses. Knowledge gained from this study will be incorporated into course work in the classroom, on field trips, and off-campus Pacific Northwest field courses taught at Western Washington University. With respect to the broader community, and aside from technical publications and lectures, results of the proposed study will be integrated into and will enhance frequently occurring field trips for professional groups, such as the Geological Society of America, National Association of Geology Teachers, and Northwest Geological Society. The public lands of the San Juan Islands and Cascades are global tourist destinations, presenting opportunity for reaching a broad audience through geologic displays in parks and in popular geologic literature. The scale of continental margin tectonics on display in western Washington is fascinating at any level of knowledge.

古生代时期，古代北美大陆（劳伦大陆）沿其西缘的生长是通过添加本地和外来来源的物质而发生的：来自大陆西侧（微地斜层）侵蚀的沉积裙带，以及由地球其他地区的板块构造位移并断层到大陆的增生地体复合体。 这项研究将考察华盛顿州西北部奇利瓦克地体增生的历史，初步研究表明至少部分地体来自欧洲西北部。 我们工作中的一个主要工具是获取火成岩和沉积岩中锆石颗粒的 U-Th-Pb 年龄。奇利瓦克地体火成岩的初步数据在北美西部未知，但在古代斯堪的纳维亚半岛（波罗的海）很常见。 在沉积岩中，一些岩石中的锆石年龄分布与北美相似，而另一些岩石中的锆石年龄分布则指向异国（欧洲或其他）故乡。额外的锆石年龄将澄清这些可能的相关性。来自锆石的进一步 Hf 同位素数据将用于测试奇利瓦克地体部分可能源自原始海洋岛弧，特别是阿拉斯加东南部增生的早期古生代亚历山大岛弧地体，而不是演化的大陆地壳（劳伦斯或其他）。 岩石单元的实地测绘将评估奇利瓦克地体中具有北美与外来亲缘关系的部分之间的遗传和结构关系。该项目的根本目标是了解板块构造机制和活动大陆边缘形成过程的基础知识。该研究计划旨在解决上述科学问题，同时加强学生的教育和培训，提高学生的兴趣以及公众对太平洋西北地区地球历史的了解。项目资金将支持本科生在现场和实验室担任助理，并支付学生参加专业会议的费用。学生对该项目的研究可能会构成高级论文的基础。从这项研究中获得的知识将被纳入西华盛顿大学教授的课堂、实地考察和校外太平洋西北实地课程中。对于更广泛的社区，除了技术出版物和讲座之外，拟议研究的结果将被纳入并加强专业团体频繁进行的实地考察，例如美国地质学会、国家地质教师协会和西北地质学会.圣胡安群岛和喀斯喀特的公共土地是全球旅游目的地，为通过公园的地质展示和流行的地质文献接触广大受众提供了机会。华盛顿西部展示的大陆边缘构造规模对于任何知识水平来说都是令人着迷的。