Collaborative Research: Mesoproterozoic Tectonics of Inboard Laurentia: Insight Into Assembly and Configuration of Rodinia

合作研究：劳伦西亚内侧的中元古代构造：洞察罗迪尼亚的组装和配置

• 批准号: 0208323
• 负责人: Matthew Heizler
• 金额: $ 4.92万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208323&HistoricalAwards=false
• 关键词: Collaborative; Research; Mesoproterozoic; Tectonics; Inboard

This project is investigating Mesoproterozoic (1300-1000 Ma) sedimentary rocks in the western U.S. to test aspects of the controversial Rodinia hypotheses. The hypothesis being tested is that the inboard record of sedimentation and tectonics in southwestern Laurentia, preserved in well-exposed sedimentary successions, can be used for understanding stresses at the surrounding plate margins, nature of drainage patterns and basins in southwestern Laurentia, and the age of possible outboard sources of detritus. The research involves structural, petrologic, and geochronologic study aimed at correlation of, and characterizing provenance for, several key areas and units. These areas represent preserved remnants of once more extensive sedimentary successions; they are well exposed, but widely separated, and correlations have been hampered by a lack of reliable geochronology. The study concentrates on the Apache Group (Arizona), Unkar Group (Grand Canyon), Crystal Spring Formation (Death Valley), and Lanora Formation (Texas). The researchers are reconstructing the regional intracratonic basinal and tectonic patterns and searching for a "fingerprint" of possible outboard sources of detritus. The geochronological studies involve: dating ash beds using precise U-Pb geochronology, U-Pb dating of detrital zircons, new in situ U-Pb microprobe dating of monazite grains, and Ar-Ar laser dating of mica grains. Sedimentary-tectonic studies are evaluating which faults were active during deposition by looking for facies changes across faults and relationships to syntectonic magmatism. Petrologic studies are emphasizing provenance of siliciclastic rocks using standard petrologic techniques. Detailed regional tests involving geochronology linked to sedimentary tectonics are providing better understanding of the tectonic setting of western Laurentia and hence the most likely adjacent outboard continental masses that collided with Laurentia from 1.3-1.0 Ga.

该项目正在调查美国西部的中元古代（1300-1000 Ma）沉积岩，以测试有争议的罗迪尼亚假说的各个方面。该假设的验证是，在暴露良好的沉积序列中保存下来的劳伦西亚西南部沉积和构造的舷内记录，可以用来了解周围板块边缘的应力、劳伦西亚西南部的排水模式和盆地的性质，以及可能的碎屑来源的舷外年龄。该研究涉及构造、岩石学和地质年代学研究，旨在对几个关键地区和单元的物源进行对比和表征。这些地区代表了曾经更广泛的沉积序列的保存遗迹；它们暴露得很好，但相隔很远，而且由于缺乏可靠的地质年代学，相关性受到了阻碍。研究集中在阿帕奇组（亚利桑那州）、昂卡尔组（大峡谷）、水晶泉组（死亡谷）和拉诺拉组（德克萨斯州）。研究人员正在重建区域性的克拉通内盆地和构造模式，并寻找可能的外部碎屑来源的“指纹”。地质年代学研究包括：用精确的U-Pb地质年代学对火山灰层进行定年，对碎屑锆石进行U-Pb定年，对独居石颗粒进行新的原位U-Pb探针定年，对云母颗粒进行Ar-Ar激光定年。沉积构造研究通过寻找断层间的相变化及其与同构造岩浆作用的关系来评价哪些断层在沉积过程中是活跃的。岩石学研究正利用标准岩石学技术强调硅质碎屑岩的物源。详细的区域测试包括与沉积构造相关的地质年代学，可以更好地了解西劳伦西亚的构造环境，从而更好地了解在1.3-1.0 Ga期间与劳伦西亚碰撞的最有可能相邻的外部大陆块。