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

科罗拉多高原下方地幔岩石圈的拉拉米德再层化：捕虏体研究

• 批准号: 1524768
• 负责人: Alan Chapman
• 金额: $ 16.34万
• 依托单位: Macalester College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-10-01 至 2018-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1524768&HistoricalAwards=false
• 关键词: Laramide; Relamination; Mantle; Lithosphere; Beneath

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.

该奖项将为地球科学领域初级研究员的职业发展提供支持。该研究将促进新的合作并加强与亚利桑那大学和莱斯大学科学家的旧伙伴关系。该项目将构成智力基础并支持三名本科生的培养。亚利桑那大学扩展项目针对 6 至 8 年级的学生开展了一项基于课堂和实地的外展计划，该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。这项研究的结果将为 Earthscope 的基本目标做出贡献，并将发表在主要同行评审的科学期刊和面向非专业人士的文章中。这项研究产生的数据将通过综合地球数据应用程序、EarthChem 和 PetDB 数据库向公众开放。越来越多的地球物理数据表明北美西部下方大陆地幔近期的地质活动性。一些证据表明，南加州下方的地幔岩石圈由于白垩纪晚期的浅俯冲事件而在构造上向东移动，并“重新层压”到科罗拉多高原过渡带（亚利桑那州中部）下方的大陆岩石圈底部。主要研究人员将通过比较来自这两个地区的地幔捕虏体的岩石成因和热历史来检验这一假设。如果亚利桑那州和加利福尼亚州的捕虏体套件以类似的方式演化，那么就可以为显生宙的重大位移和随后美国西南部地幔岩石圈的重建提供有力的证据。这项研究将为了解北美西部下方的地幔位移提供地球动力学和地质背景。这项研究将为美国西南部地幔岩石圈的起源和演化提供关键约束，增强识别全球现代和古代类似环境的能力，更好地了解俯冲角对克拉通活动边缘过渡区地幔岩石圈稳定性的影响，并很有可能识别南加州地幔岩石圈的残余物，该残余物已被“重新层压”在下面 亚利桑那州中部。这一结果意味着南加州地幔碎片发生了 500 公里的构造位移，并为科罗拉多高原相对于邻近地质省份的长期强度以及高原下方活跃的岩石圈分层提供了有趣的解释。