Collaborative Research: Testing models for the Late Jurassic Nevadan Orogeny: Age, provenance, and structural evolution of the Galice and Mariposa basins, OR and CA

拟议的研究将提高对俄勒冈州南部和加利福尼亚州北部北美大陆边缘的发展的理解，就在一个关键的和知之甚少的收缩变形时期之前和期间。在这一时期（晚侏罗世），造山活动分别封闭了克拉马斯山脉西部的加利斯和马里波萨沉积盆地和塞拉山脉西部的马里波萨盆地。盆地沉积物来源、沉积年代、变质作用和变形程度的细节，可能提供造山事件之前和期间的最佳地质记录。该项目为本科生和研究生提供了重要的教育效益，需要整合一系列学科知识和技能，而这些知识和技能在课堂上是无法复制的。该项目将在研究生和本科生阶段招收女性和少数族裔学生，这些学生将成为研究的全面参与者，而不是旁观者。通过这项研究的体验式学习将提供技能发展和培训，这将直接转化为STEM劳动力。此外，突出这项研究和关键兴趣领域的实地指南将通过森林服务区和NSF Flyover Country®应用程序广泛传播，以提高公众的科学素养。对金矿开采的持续兴趣和形成本研究重点的岩石的开采历史增加了公众参与的可能性。克拉马斯山脉和西塞拉利昂省的上侏罗统加利斯组和马里波萨组一直被认为是了解美国科迪勒拉大陆边缘中中生代历史的基础。晚侏罗世内华达造山运动的两种相反的构造模式不同地解释了加利斯和马里波萨沉积的构造背景和时代。第一个模型认为马里波萨组的起源是在一个洋内盆地中，该盆地沿着相反倾斜的俯冲带逐渐关闭，而年龄相当的加利斯组代表了一个原产于北美西部边缘的弧间盆地。在第二种模式中，这两种地层都出现在沿北美西部边缘东倾的长寿命俯冲带之上的张拉盆地中。由于这些地层构成了内华达晚侏罗世变形期间最年轻的岩石，因此沉积年龄、沉积物来源以及变形的运动学和样式的细节对于提供所提出的构造模型和评估其可行性至关重要。对这些盆地进行全面、综合的分析，包括岩相特征、碎屑锆石U-Pb年龄和Hf分析、重矿物分析、沉积构造解释、变质程度评估、变形时间和运动学分析，将为修改和完善对晚侏罗世大陆边缘的认识提供一个强有力的框架。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The proposed research will improve the understanding of the development of the North American continental margin in southern Oregon and northern California just prior to and during a critical and poorly understood period of contractional deformation. During this time (the Latest Jurrassic), mountain building closed the Galice and Mariposa sedimentary basins in the western Klamath and Sierra mountains, respectively. Details of the basins’ sediment sources, depositional ages, and extent of metamorphism and deformation may provide the best geologic record just prior to and during the mountain-building event. The project provides key educational benefits for students at the undergraduate and graduate level, requiring integration of a range of disciplinary knowledge and skills that cannot be duplicated in a classroom. The project will recruit women and underrepresented minority students at graduate and undergraduate levels, and these students will be full participants in the research, not observers. The experiential learning through this research will provide skill development and training that will translate directly to the STEM workforce. In addition, field guides highlighting this research and key areas of interest will be broadly disseminated through Forest Service districts and the NSF Flyover Country® app, improving public scientific literacy. The ongoing interest in gold mining and the mining history of the rocks that form the focus of this research increase the likelihood of public engagement.The Upper Jurassic Galice and Mariposa Formations in the Klamath Mountains and western Sierran provinces have long been considered fundamental to understanding the mid-Mesozoic history of the U.S. Cordilleran continental margin. Two opposing tectonic models for the Late Jurassic Nevadan orogeny variously interpret the tectonic setting and age of Galice and Mariposa deposition. The first model invokes the genesis of the Mariposa Formation in an intra-oceanic basin that progressively closed along oppositely dipping subduction zones, while the age-equivalent Galice Formation represents an inter-arc basin native to the western margin of North America. In the second model, both formations occur within transtensional basins above an east-dipping, long-lived subduction zone along the western North American margin. Because these strata constitute the youngest rocks deformed during the Late Jurassic Nevadan deformation, details of depositional age, sediment provenance, and the kinematics and style of deformation are critical to informing the proposed tectonic models and assessing their viability. This comprehensive and integrated analysis of each of these basins that includes petrofacies characterization, detrital zircon U-Pb age and Hf analysis, heavy mineral analysis, interpretation of sedimentary structures, assessment of the degree of metamorphism, and analysis of the timing and kinematics of deformation, will provide a robust framework for modification and refinement of the understanding of the Late Jurassic continental margin.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.