Collaborative Research: Mesoproterozoic Tectonics of Inboard Southwestern Laurentia: Insight Into Assembly and Configuration of Rodinia From Study of Sedimentary Successions

合作研究：劳伦西亚西南内侧的中元古代构造：从沉积演替研究中洞察罗迪尼亚的组装和构造

• 批准号: 0208463
• 负责人: Karl Karlstrom
• 金额: $ 11.49万
• 依托单位: University of New Mexico
• 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 2006-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208463&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。正在测试的假设是，西南劳伦西亚沉积和构造的内侧记录，保存在暴露良好的沉积层序中，可用于了解周围板块边缘的应力，西南劳伦西亚排水模式和盆地的性质，以及可能的外侧碎屑来源的年龄。 该研究涉及结构、岩石学和地质年代学研究，旨在关联几个关键区域和单元并描述其来源特征。这些地区代表了曾经更广泛的沉积序列的保存遗迹；它们暴露得很充分，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。该研究集中在阿帕奇群（亚利桑那州）、翁卡群（大峡谷）、水晶泉地层（死亡谷）和拉诺拉地层（德克萨斯州）。研究人员正在重建区域克拉通内盆地和构造模式，并寻找可能的外侧碎屑来源的“指纹”。地质年代学研究包括：使用精确的 U-Pb 地质年代学对灰床进行测年、碎屑锆石的 U-Pb 测年、独居石颗粒的新原位 U-Pb 微探针测年以及云母颗粒的 Ar-Ar 激光测年。沉积构造研究通过寻找断层间的相变化以及与同构造岩浆作用的关系来评估哪些断层在沉积过程中活跃。岩石学研究强调使用标准岩石学技术来确定硅质碎屑岩的来源。涉及与沉积构造相关的地质年代学的详细区域测试有助于更好地了解劳伦西亚西部的构造环境，以及最有可能在 1.3-1.0 Ga 期间与劳伦西亚碰撞的邻近外侧大陆块。