Development of a 4-D Model of Crustal Evolution in the Northern Rocky Mountains

为了优化在北方落基山脉/大平原中EarthScope（ES）资源的当前和未来部署，来自佛罗里达大学、蒙大拿州立大学和美国地质调查局的一组地球科学家正在进行针对开发综合时空（即，四维地壳演化格架。 特别是，该地区包含北美大陆地壳最神秘的部分之一，大福尔斯构造带（GFTZ）。 这种长寿的地壳结构在北美拥有最广泛的岩石记录（年龄为40亿年），并对该地区的地质历史产生了重大影响，包括断层和地震活动的年轻时期，岩浆活动和矿床的分布，以及资源丰富的沉积盆地的形成。 例如，GFTZ和Trans-Hudson造山带的交汇处，大约在18亿年前形成，现在是一个主要的石油资源省，威利斯顿盆地。 同样，北方落基山脉的中生代构造复活、岩浆活动、地震活动和矿化作用都集中在GFTZ，这就为古代构造和事件如何控制现代地球过程和资源分布提供了额外的可能性。（离子探针U-Pb），热年代学（多颗粒和单颗粒40 Ar-39 Ar），（主要和微量元素）技术，从露头，深测试威尔斯，和捕虏体（地幔和下地壳的碎片通过火山爆发带到地表）。 这些结果对于优化ES资源的部署和最终为北美北方落基山脉/北方大平原部分开发一个综合的4-D框架都至关重要。 这个四维框架对于以下几个方面至关重要：1）揭示地质记录中最有趣的大陆形成事件之一，即北美劳伦阶的形成; 2）了解地壳和地幔中的混合碰撞事件是如何记录的; 3）这些古代事件在多大程度上影响了随后北方落基山脉/大平原的地壳和岩石圈演化。 该研究小组正在利用所有三个组织（佛罗里达大学，蒙大拿州立大学和美国地质调查局）的设施。 研究生和本科生的参与为地质和分析技能提供了重要的劳动力培训。 这项研究的结果将被集成到不断发展的蒙大拿州地理信息系统/DEM地质图基础正在开发的蒙大拿州州立大学。 所有地球化学和地质年代学数据将以交互式网络格式在数字和空间上显示，并可供地球科学家、教育工作者和公众访问。 还将通过会议介绍和同行评审期刊传播结果。

0545751MuellerIn order to optimize current and future deployment of EarthScope (ES) resources in the northern Rocky Mountains/Great Plains, a group of earth scientists from the University of Florida, Montana State University, and the U.S. Geological Survey are conducting research directed toward development of an integrated temporal and spatial (i.e., 4-D) framework for crustal evolution in this region. In particular, this region contains one of the most enigmatic segments of continental crust in North America, the Great Falls tectonic zone (GFTZ). This long-lived crustal structure has the most temporally extensive rock record in North America (ages to 4 billion years) and has had a major impact on the geologic history of this region, including younger episodes of faulting and seismicity, distribution of magmatism and ore deposits, and the creation of resource-rich sedimentary basins. For example, the intersection of the GFTZ and Trans-Hudson orogen, which developed ~ 1.8 billion years ago, is now the site of a major petroleum resource province, the Williston basin. Similarly, Phanerozoic structural reactivation, magmatism, seismicity, and mineralization in the northern Rocky Mountains is concentrated in the GFTZ, which leads to additional possibilities of how ancient structures and events may control modern earth processes and the distribution of resources.The research group is applying modern geochronologic (ion probe U-Pb), thermochronologic (multi-and single grain 40Ar-39Ar), and geochemical (major and trace elements) techniques to samples from outcrops, deep test wells, and xenoliths (pieces of the mantle and lower crust brought to the surface via volcanic eruptions). These results will be critical for both optimizing the deployment of ES resources and ultimately developing an integrated 4-D framework for the northern Rocky Mountain/northern Great Plains portion of North America. This 4-D framework is essential to: 1) unraveling one of the most intriguing episodes of continent formation in the geologic record, the formation of Laurentian North America; 2) understanding how the amalgamating collisional events were recorded in the crust and mantle; and 3) to what extent these ancient events affected subsequent crustal and lithospheric evolution in the northern Rocky Mountains/Great Plains. The research team is utilizing facilities from all three organizations (University of Florida, Montana State University, and the U.S. Geological Survey). Student participation at the graduate and undergraduate level is providing critical workforce training in geologic and analytical skills. The results of this research will be integrated into the evolving Montana GIS/DEM geologic map base being developed at Montana State University. All of the geochemical and geochronologic data will be numerically and spatially displayed in an interactive web format and accessible to geoscientists, educators, and the general public. Results will also be disseminated via meeting presentations and peer reviewed journals.