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.

古北美大陆（劳伦大陆）沿着其西缘在古生代的生长是由于当地和外来物质的加入而发生的：一个沉积裙来自大陆西侧的侵蚀（冒地斜），还有一个由增生的杂岩组成的复合体，它被来自地球仪其他部分的板块构造移动并断裂进入大陆。 这项研究的研究将审查历史的增生奇利瓦克在西北华盛顿约初步研究表明，至少部分来自欧洲西北部。 我们工作的主要工具是获取火成岩和沉积岩中锆石的U-Th-Pb年龄。从奇利瓦克火山岩中获得的初步数据显示，北美洲西部的火山岩年龄未知，但在古代斯堪的纳维亚半岛（波罗的海）很常见。 在沉积岩中，锆石的年龄分布在一些岩石中类似于北美，而在其他岩石中则指向一个外来的（欧洲或其他）家园。额外的锆石年龄将澄清这些可能的相关性。锆石中的Hf同位素数据将进一步用于测试奇利瓦克火山岩部分来自原始海洋岛弧的可能性，特别是阿拉斯加东南部的早古生代亚历山大弧火山岩，而不是演化的大陆地壳（劳伦提斯或其他）。 岩石单元的实地测绘将评估具有北美与外来亲缘关系的奇利瓦克地区之间的遗传和结构关系。该项目的基本目标是对板块构造机制和活动大陆边形成过程的基本认识，研究计划旨在解决上述科学问题，并加强对学生的教育和培训，提高公众对太平洋西北部地球历史的兴趣和理解。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形成高级论文的基础。从这项研究中获得的知识将被纳入课堂，实地考察，并在西华盛顿大学教授校外太平洋西北地区实地课程的课程工作。关于更广泛的社区，除了技术出版物和讲座，拟议的研究结果将被纳入并将加强经常发生的实地考察的专业团体，如美国地质学会，地质教师全国协会，和西北地质学会。圣胡安群岛和瀑布的公共土地是全球旅游目的地，通过公园和流行的地质文献中的地质展示，为广大观众提供了机会。在华盛顿西部展示的大陆边缘构造的规模在任何知识水平上都是迷人的。