Laramide Relamination of Mantle Lithosphere Beneath the Colorado Plateau: A Xenolith Study

该奖项将为地球科学领域初级调查员的职业发展提供支持。这项研究将促进新的合作，并加强与亚利桑那大学和赖斯大学科学家的旧伙伴关系。该项目将为三名本科生的培养提供智力基础和支持。通过亚利桑那大学的延伸，一个面向6-8年级学生的课堂和实地推广计划将与这项研究相结合。通过该计划制作的课程材料将通过科学教育资源中心(SERC)与地球科学界共享。这项研究的结果将有助于地球望远镜的基本目标，并将在主要的同行评议的科学期刊上发表，并在一篇面向非专家的文章中发表。这项研究产生的数据将在综合地球数据应用程序、EarthChem和PetDB数据库中向公众开放。越来越多的地球物理数据表明，北美西部之下的大陆地幔在地质上最近的活动。几条证据表明，由于晚白垩世浅俯冲事件，南加州下方的地幔岩石圈在构造上向东移动，并与科罗拉多高原过渡带(亚利桑那州中部)之下大陆岩石圈的底部重新分层。首席研究员将通过比较这两个地区的地幔捕虏体的岩石成因和热史来检验这一假设。如果亚利桑那州和加利福尼亚州捕虏体组合以类似的方式演化，那么可以很好地证明美国西南地幔岩石圈的主要显生界位移和随后的重建。这项研究将提供地球动力学和地质背景，以了解北美西部之下的地幔位移。这项研究将对美国西南部地幔岩石圈的起源和演化提供关键约束，增强识别世界范围内现代和古代类似环境的能力，更好地理解俯冲角度对克拉通活动边缘过渡带地幔岩石圈稳定性的影响，以及识别出亚利桑那州中部之下被重新分层的南加州地幔岩石圈残留物的可能性很高。这一结果将意味着南加州地幔碎片的500公里构造位移，并为科罗拉多高原相对于邻近地质省份的长期强度和高原下活跃的岩石圈拆沉提供了有趣的解释。

This award will provide support for the career development of a junior investigator in the area of Earth Sciences. The study will foster new collaborations and enhance old partnerships with scientists at the University of Arizona and Rice University. This project will constitute the intellectual basis and support the training for three undergraduate students. A classroom- and field-based outreach program, through University of Arizona Extension and intended for students in grades 6-8, will be integrated with this research. Course materials produced through this program will be shared with the geosciences community through the Science Education Resource Center (SERC). The results from this study will contribute to the fundamental goals of Earthscope and will be published in major peer-reviewed scientific journals and in an article for non-specialists. Data resulting from this study will be made accessible to the public in Integrated Earth Data Applications, EarthChem, and PetDB databases.A growing body of geophysical data suggests geologically recent mobility of the continental mantle beneath western North America. Several lines of evidence suggest that mantle lithosphere beneath southern California was tectonically displaced eastward by a Late Cretaceous episode of shallow subduction and "relaminated" to the base of the continental lithosphere beneath the Colorado Plateau transition zone (central Arizona). The principal investigator will test this hypothesis by comparing the petrogenetic and thermal histories of mantle xenoliths derived from both areas. If Arizona and California xenolith suites evolved in a similar manner, then a strong case can be made for major Phanerozoic displacement and subsequent reconstruction of southwest U.S. mantle lithosphere. This study will provide a geodynamic and geologic context to understand mantle displacements beneath western North America. This research will provide key constraints on the origin and evolution of mantle lithosphere beneath the southwest U.S., an enhanced ability to recognize modern and ancient analogous settings worldwide, an improved understanding of the effects of subduction angle on the stability of mantle lithosphere at craton active margin transition zones, and a high probability of recognizing a remnant of the southern California mantle lithosphere that has been "relaminated" beneath central Arizona. This result would imply a 500 km tectonic displacement of the southern California mantle fragment and provide intriguing explanations for the long-term strength of the Colorado Plateau relative to adjacent geologic provinces and for active lithospheric delamination beneath the plateau.