Collaborative Research: Brittle-plastic deformation, fluid-rock interaction, and extensional reactivation along Laramide thrust faults in the Sangre de Cristo Mountains, Colorado

合作研究：科罗拉多州桑格雷德克里斯托山脉拉拉米德逆冲断层沿线的脆塑性变形、流体-岩石相互作用和伸展再活动

• 批准号: 2115719
• 负责人: John Singleton
• 金额: $ 25.76万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2115719&HistoricalAwards=false
• 关键词: Collaborative; Research; Brittle; plastic; deformation

This collaborative project investigates the deformation history of structures involved in formation of the Rocky Mountains and Rio Grande rift in southern Colorado. Through detailed fieldwork and laboratory analyses, the investigators will evaluate the timing and directions of motion along fault zones and the role of fluids in weakening these zones and facilitating tectonic activity. These results will help geoscientists better understand how rock strength affects fundamental mountain-building processes. This project will directly support thesis work for three Colorado State University graduate students and three Washington and Lee University undergraduate students, who will disseminate research results via publications and conference presentations. The study area in the Sangre de Cristo Mountains borders Great Sand Dunes National Park, which receives over half a million visitors each year, and the investigators will communicate research results with the park geologist to help provide additional geological context for educational outreach. This project will also support three years of an interdisciplinary student-led research seminar on the Sangre de Cristo Mountains within the Colorado State University Department of Geosciences. This seminar will involve at least 15 students (graduate and undergraduate) and 7 faculty members from across the Department, exposing students to a highly interdisciplinary approach to research. The project area in the Sangre de Cristo Mountains exposes some of the deepest Laramide and Rio Grande rift structural levels in the Rocky Mountain region, offering a rare opportunity to investigate deformation near the brittle-plastic transition. The investigators hypothesize that fluid-rock interactions weakened faults in this region, allowing contractional deformation to take place at relatively low stresses during the Laramide orogeny and extensional reactivation to occur on structures not optimally oriented for failure during development of the Rio Grande rift. Widespread shortening across the Laramide orogen may have been facilitated by fluid-related weakening, and extensional reactivation of thrust faults may represent a fundamental component of orogenic collapse. The investigators will test their hypotheses using a multidisciplinary research approach that includes geologic mapping, microstructural analysis, electron backscatter diffraction, Fourier transform infrared spectroscopy, stable isotope analysis, fluid inclusion analysis, geochemistry, and geo/thermochronology. Data generated in this project will provide key constraints on the stresses, temperatures, deformation mechanisms, and fluid involvement associated with intraplate shortening near the strongest part of the crust. This research will also shed light on the relations between Laramide contraction and Rio Grande rift extension and the role of shear zone geometry and rheology on extensional reactivation, providing a framework for understanding extensional reactivation of thrusts in other orogens.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.

这个合作项目调查的变形历史的结构参与形成的落基山脉和格兰德河裂谷在南部科罗拉多。通过详细的实地考察和实验室分析，研究人员将评估沿着断层带运动的时间和方向，以及流体在削弱这些区域和促进构造活动方面的作用。 这些结果将有助于地球科学家更好地了解岩石强度如何影响基本的造山过程。该项目将直接支持三名科罗拉多州立大学研究生和三名华盛顿和李大学本科生的论文工作，他们将通过出版物和会议演讲传播研究成果。Sangre de Cristo山脉的研究区域与每年接待50多万游客的大沙丘国家公园接壤，研究人员将与公园地质学家交流研究结果，以帮助为教育推广提供额外的地质背景。该项目还将支持在科罗拉多州立大学地球科学系内举办为期三年的由学生领导的关于Sangre de Cristo山脉的跨学科研究研讨会。本次研讨会将涉及至少15名学生（研究生和本科生）和7名教师来自整个部门，让学生接触到高度跨学科的研究方法。 Sangre de Cristo山脉的项目区暴露了落基山脉地区最深的Laramide和格兰德河裂谷构造层，为研究脆塑性转变附近的变形提供了难得的机会。研究人员假设，流体-岩石相互作用削弱了该地区的断层，使收缩变形发生在相对较低的应力在Laramide orthopathy和伸展复活发生在结构上没有最佳取向的失败在格兰德河裂谷的发展。广泛缩短整个Laramide造山带可能是由流体相关的削弱，和逆冲断层的伸展活动可能是一个基本组成部分的造山塌陷。研究人员将使用多学科研究方法来测试他们的假设，包括地质测绘，显微结构分析，电子背散射衍射，傅立叶变换红外光谱，稳定同位素分析，流体包裹体分析，地球化学和地质/热年代学。在这个项目中产生的数据将提供与地壳最强部分附近板内缩短相关的应力，温度，变形机制和流体参与的关键约束。这项研究也将阐明Laramide收缩和格兰德河裂谷延伸之间的关系，剪切带的几何形状和流变学的作用，对拉伸复活，提供了一个框架，为理解在其他orogenes.This奖项的逆冲断层的拉伸复活反映了NSF的法定使命，并已被认为是值得通过使用该基金会的智力价值和更广泛的影响审查标准进行评估的支持。