Collaborative Research: Structure and Dynamics of the North American Craton - An EarthScope Swath from the Ozarks to the Grenville Front

合作研究：北美克拉通的结构和动力学 - 从奥沙克到格伦维尔锋线的 EarthScope 地带

• 批准号: 1053354
• 负责人: Gary Pavlis
• 金额: $ 67.54万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-15 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1053354&HistoricalAwards=false
• 关键词: Collaborative; Research; Structure; Dynamics; North

This project is directed at improving our understanding of the lithosphere-scale structure of North America's stable continental interior (Midcontinent cratonic platform). The study area includes some of the world?s best examples of cratonic platform lithosphere structures. Specifically, it spans the Ozark Dome and the Illinois Basin (including the abrupt boundary between them along which the Precambrian/Cambrian unconformity displays over 7.5 km of structural relief), as well as the Rough Creek Graben and other major fault zones including the Wabash Valley Seismic Zone. It also crosses major Proterozoic sutures and the enigmatic Eastern Granite-Rhyolite province. The study is intended to address seven fundamental tectonic issues: (1) structure of intracratonic uplifts and basins; (2) Proterozoic assembly of the North American cratonic platform; (3) deep structure of intracontinental rifts and fault-and-fold zones; (4) lithospheric controls on intraplate seismicity; (5) deep structure of the midcontinent?s unusual anorogenic granite-rhyolite province; (6) structural and lithospheric controls on ?cratonization? of the North American platform; and (7) understanding the nature of the strong gravity and magnetic-field anomalies in the region. The project is focused on operation of a three-dimensional, broadband, passive seismic array centered over the Illinois Basin. The array is embedded within the Earthscope Transportable Array, and is designed to provide enhanced resolution of subsurface structures in the region. The experiment involves deployment of 120 temporary seismograph stations over a 3-year period coinciding with the operation of the Transportable Array in the area; site occupation will roll in four distinct stages using a maximum of 60 simultaneously operating stations. The acquired seismic data are being analyzed using a variety of state-of-the-art seismic analysis tools: travel-time tomography using teleseismic P and S waves; wave-field imaging using industry-developed methods of stacking signals to improve signal-to-noise ratio and ?migration? of inferred seismic sources to their proper geometric position; and a detailed analysis of seismicity recorded on this dense array, to better locate earthquake sources and characterize faults. Estimates from previous work in the area suggest that approximately 100 local earthquakes and 12,000 mining explosions will be recorded during the course of the three-year field experiment. The project also incorporates an integrated education and outreach component, involving: (1) in-service teacher workshops designed to expand the pool of master teachers knowledgeable about EarthScope science; (2) a teacher Research Fellows program to include high school science teachers in summer research teams; (3) involvement of students and the public in EarthScope-related activities using already established connections with schools, pre-college research symposia, and State Survey outreach programs (field trips; open houses; public presentations); (4) development of material for "Active Earth" displays for regional outreach, and for incorporation in widely used introductory geoscience textbooks; (5) engagement of undergraduate students through a Research Experience for Undergraduates program; and (6) graduate student education three research universities.

该项目旨在提高我们对北美稳定大陆室内（中大陆的克拉通平台）岩石圈规模结构的理解。 研究领域包括世界上一些岩石圈结构的最佳例子。 具体而言，它跨越了Ozark圆顶和伊利诺伊州盆地（包括沿它们之间的突然边界，前寒武纪/寒武纪的不整合体显示了超过7.5 km的结构浮雕），以及Rough Creek Graben和其他主要断层区域，包括Wabash Valley地震区。 它还跨越主要的植物缝合线和神秘的东部花岗岩 - 丝醇省。 该研究旨在解决七个基本构造问题：（1）裂谷内隆起和盆地的结构； （2）北美克拉通平台的properokoic集会； （3）肠内裂谷和断层和折叠区域的深层结构； （4）岩石圈对板内地震性的控制； （5）中大陆的深层结构，不寻常的厌氧 - 丝状省； （6）对cratonization的结构和岩石圈控制？北美平台； （7）了解该地区强重力和磁场异常的性质。 该项目的重点是以伊利诺伊州盆地为中心的三维，宽带，被动地震阵列的运行。 该阵列嵌入了可运输的地球阵列中，旨在提供该地区地下结构的增强分辨率。 该实验涉及在3年的时间内部署120个临时地震仪站，与该地区可运输阵列的运行一致；现场职业将使用最多60个同时运营的站点在四个不同的阶段滚动。 正在使用各种最先进的地震分析工具分析获得的地震数据：使用远距离震动P和S波的旅行时间层析成像；使用行业开发的堆叠信号方法来提高信噪比和迁移的波浪现象？推断的地震来源，以达到其适当的几何位置；以及对此密集阵列记录的地震性的详细分析，以更好地定位地震来源并表征故障。 该地区先前工作的估计表明，在三年实地实验过程中，将记录大约100次当地地震和12,000次采矿爆炸。 该项目还结合了综合的教育和外展部分，其中涉及：（1）在职教师研讨会，旨在扩大对Earthscope Science知识渊博的大师教师的库； （2）一项教师研究研究员计划，包括夏季研究团队中的高中科学教师； （3）使用已经建立的与学校建立联系，大学前研究研讨会和州调查外展计划（实地考察；开放式房屋；公共演讲）的学生和公众参与与地球相关的活动； （4）开发用于区域外展的“活跃地球”展示的材料，并将其纳入广泛使用的地球科学教科书中； （5）通过本科课程的研究经验与本科生的参与； （6）研究生教育三所研究。