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

这项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发展的理解，就在一个关键的、鲜为人知的收缩变形时期之前和期间。在此期间(最晚的侏罗纪)，造山作用分别关闭了克拉马斯山脉西部的加利斯盆地和马里波萨沉积盆地。盆地的沉积来源、沉积年龄、变质和变形程度的详细信息可能会在造山事件之前和期间提供最好的地质记录。该项目为本科生和研究生提供了关键的教育益处，需要整合一系列无法在课堂上复制的学科知识和技能。该项目将招收研究生和本科生中的女性和代表性不足的少数族裔学生，这些学生将全面参与研究，而不是观察员。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，将通过林业局地区和NSF Flyover Country®应用程序广泛传播强调这项研究和感兴趣的关键领域的实地指南，以提高公众的科学素养。对金矿开采的持续兴趣和形成这项研究重点的岩石的开采历史增加了公开参与的可能性。长期以来，克拉马斯山脉和西西耶兰省的上侏罗统加利斯和马里波萨地层一直被认为是理解美国科迪勒兰大陆边缘中-中生代历史的基础。晚侏罗世内华达造山的两种截然相反的构造模式对加利斯和马里波萨沉积的构造背景和时代有不同的解释。第一种模式提出马里波萨组的成因是在一个洋内盆地中，该盆地沿着相对倾斜的俯冲带逐渐闭合，而与年龄相当的加利斯组代表了一个原产于北美西缘的弧间盆地。在第二种模式中，这两种建造都发生在北美西部边缘向东倾斜的长期俯冲带上方的伸展盆地内。由于这些地层是在晚侏罗世内华达变形期间变形的最年轻的岩石，因此沉积年龄、沉积物来源、运动学和变形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。这种对每个盆地的全面和综合的分析，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、变质程度评估以及变形的时间和运动学分析，将为修改和完善对晚侏罗世大陆边缘的理解提供坚实的框架。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.