Jura-Cretaceous Sinistral Displacement of Terranes Along the Northern Cordilleran Margin

汝拉-白垩纪北科迪勒拉边缘地体左旋位移

• 批准号: 1818509
• 负责人: George Gehrels
• 金额: $ 20.19万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-12-01 至 2022-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1818509&HistoricalAwards=false
• 关键词: Jura; Cretaceous; Sinistral; Displacement; Terranes

One of the most controversial aspects of North American geology concerns the degree to which rocks extending from California to Alaska have been transported south and then north along the continental margin due to convergence and translation between the North American and ancestral Pacific tectonic plates during Late Cretaceous-Paleogene time. Some relationships suggest limited mobility - geologic features remain close to where they formed. In contrast, other data sets suggest thousands of kilometers of transport - rocks in much of Alaska, British Columbia, Washington, and Oregon first moved south to the latitude of Mexico, and then moved back north to their present positions. The uncertainty in coast-wide transport hinders our ability to reconstruct the geologic evolution of western North America and to understand the origin (and future discovery) of important energy and mineral resources located in these regions. This project focuses on determining the amount of southward motion accommodated on fault systems that extend from northwestern Washington to southern Alaska. In addition to the scientific goals of the project, the award is supporting important societal outcomes by training students in an important discipline that is contributing to the development of a diverse, globally competitive STEM workforce. The research project also involves collaboration with researchers from the British Columbia Geological Survey.This project involves field and laboratory analysis of fault systems that may have accommodated up to 1600 km of southward motion of rock assemblages. The investigators will conduct detailed structural analyses to determine the amounts of displacement on recognized faults, map areas between recognized faults to evaluate continuity, and collect samples that will constrain when motion occurred. Field studies will focus on faults in coastal British Columbia given that these are the best-known segments of the faults - their extensions into Alaska and Washington are not well constrained. The scientific objectives of the project include: 1) testing the hypotheses that each of these two fault record approximately 800 kilometers of Late Jurassic-Early Cretaceous sinistral motion, (2) evaluating the alternative interpretation that the Insular and Intermontane tectonostratigraphic terranes are separated by an Early Cretaceous suture zone, (3) using this new information to evaluate current models for Cordilleran paleogeography, and (4) establishing the sinistral faults as world-class examples of shear zones operating within an active magmatic arc during oblique subduction. Field and laboratory analyses will be conducted in large part by undergraduate students at the University of Arizona in an effort to provide opportunities to learn techniques of geologic mapping in a frontier area, and to perform geochronologic and geochemical analyses using state-of-the-art instruments at the Arizona LaserChron Center (University of Arizona). Each student will be sufficiently engaged in the field and laboratory studies that they will be able to prepare a manuscript for publication that includes detailed and regional geologic maps, descriptions of critical structural/intrusive relations, large geochronologic and geochemical data sets, and interpretations of broad significance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

北美地质学最具争议的方面之一是，由于北美晚期北美和太平洋构造板之间的融合和转化，在白垩纪晚期的北美和太平洋构造板之间的融合和翻译，从加利福尼亚到阿拉斯加的岩石沿着大陆边缘向南运输。一些关系表明有限的移动性 - 地质特征仍然接近它们形成的位置。相比之下，其他数据集表明，在阿拉斯加，不列颠哥伦比亚省，华盛顿和俄勒冈州大部分地区的岩石中，数千公里的岩石首先向南移至墨西哥纬度，然后向北移至他们现在的职位。沿海运输的不确定性阻碍了我们重建北美西部地质演变并了解这些地区重要能源和矿产资源的起源（以及未来发现）的能力。该项目着重于确定从华盛顿西北部到阿拉斯加南部的断层系统上的南部运动量。除了该项目的科学目标外，该奖项还通过在重要学科中培训学生的重要社会成果支持重要的社会成果，这有助于发展多样化的全球竞争性STEM劳动力。该研究项目还涉及与不列颠哥伦比亚省地质调查局的研究人员的合作。该项目涉及对故障系统的现场和实验室分析，这些故障系统可能容纳了高达1600公里的岩石组合运动。研究人员将进行详细的结构分析，以确定公认故障的位移量，公认的故障之间的地图以评估连续性，并收集在运动时会约束的样品。鉴于这些是最著名的部分，因此现场研究将重点放在不列颠哥伦比亚沿岸的断层 - 它们向阿拉斯加和华盛顿的扩展没有很好的约束。该项目的科学目标包括：1）测试假设的两个故障记录中的每一个，大约800公里的侏罗纪晚期 - 白垩纪的辛迪斯特运动，（2）评估替代性解释，该解释是隔离和跨内部构造构造的构造构造术语的分离的，使用了早期的杂货店，以此来评估这种模型，以此来评估这种新的杂物（3）。古地理学和（4）建立罪行断层作为在倾斜俯冲过程中活跃岩浆弧内运行的剪切区的世界一流的例子。亚利桑那大学的本科生将在很大程度上进行现场和实验室分析，以便提供机会，以学习在边境地区学习地质映射技术，并使用亚利桑那州Laserchron Laserchron Center（Arizona University of Arizona）使用最先进的地质学和地球化学分析进行地质学和地球化学分析。 Each student will be sufficiently engaged in the field and laboratory studies that they will be able to prepare a manuscript for publication that includes detailed and regional geologic maps, descriptions of critical structural/intrusive relations, large geochronologic and geochemical data sets, and interpretations of broad significance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review 标准。

项目成果

Evidence for regionally continuous Early Cretaceous sinistral shear zones along the western flank of the Coast Mountains, coastal British Columbia, Canada

加拿大不列颠哥伦比亚省沿海海岸山脉西侧早白垩世左旋剪切带区域连续的证据

• DOI: 10.1130/ges02502.1
• 发表时间: 2022
• 期刊: Geosphere
• 影响因子: 2.5
• 作者: Wang, Jordan W.;Gehrels, George;Kapp, Paul;Sundell, Kurt
• 通讯作者: Sundell, Kurt