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内部（中大陆板块地台）岩石圈尺度结构的理解。 该研究领域包括一些世界？是最好的岩石圈构造的例子。 具体而言，它跨越了奥扎克穹丘和伊利诺伊盆地（包括它们之间的陡峭边界，沿该边界沿着，前寒武纪/寒武纪不整合面显示出超过7.5 km的构造起伏），以及粗溪地堑和其他主要断层带，包括瓦巴什山谷地震带。 它还穿过主要的元古代缝合线和神秘的东部花岗岩流纹岩省。 该研究旨在解决七个基本构造问题：（1）克拉通隆起和盆地的结构;（2）北美克拉通地台的元古宙组装;（3）陆内裂谷和断层-褶皱带的深部结构;（4）岩石圈对板内地震活动的控制;（5）中大陆的深部结构？（6）构造和岩石圈控制？同化？（7）了解该地区强重磁场异常的性质。 该项目的重点是一个三维，宽带，被动地震阵列在伊利诺伊盆地为中心的操作。 该阵列嵌入Earthscope便携式阵列，旨在提高该地区地下结构的分辨率。 该试验涉及在三年期间内部署120个临时地震仪台站，与该地区移动式地震台阵的运作同时进行;场地占用将分四个不同阶段进行，最多使用60个同时运作的台站。 正在使用各种最先进的地震分析工具分析所获得的地震数据：使用超声波P波和S波的走时层析成像;使用工业开发的叠加信号方法进行波场成像，以提高信噪比;移民？将推断出的震源定位到正确的几何位置;并对这一密集阵列上记录的地震活动进行详细分析，以更好地定位震源和确定断层。 根据以前在该地区工作的估计，在为期三年的实地试验期间，将记录到大约100次当地地震和12 000次采矿爆炸。 该项目还包括一个综合的教育和推广部分，包括：（1）在职教师讲习班，旨在扩大掌握地球观测科学知识的教师队伍;（2）教师研究员方案，将高中科学教师纳入暑期研究小组;（3）利用与学校的现有联系，大学预科研究座谈会，和州调查外联方案（实地考察;开放参观;公开演讲）;（4）为区域宣传开发“活动地球”展示材料，并将其纳入广泛使用的地球科学入门教科书;（5）通过本科生研究经验计划吸引本科生参与;（6）三所研究型大学的研究生教育。