Collaborative Research: Investigating Slip Distribution over Multiple Timescales across the Central Walker Lane: Implications for the Evolution of an Active Tectonic Plate Boundary

合作研究：调查中央沃克巷多个时间尺度的滑移分布：对活动板块边界演化的影响

• 批准号: 1419855
• 负责人: Warren Sharp
• 金额: $ 7.46万
• 依托单位: Berkeley Geochronology Center
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1419855&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Slip; Distribution

The Walker Lane is an enigmatic zone of northwest-trending belt of deformation that straddles the California and Nevada border and is nearly 700 kilometers long. It is primarily characterized by northwest-striking faults that show evidence of right-lateral shear. The faults of the Walker Lane have formed in response to deformation related to relative motion of the Pacific and North American tectonic plates as they slide past one another. The goal of this study is to investigate the spatial and temporal distribution of fault slip and motion along a set of active faults across the relatively narrow eastern part of the central Walker Lane in Nevada. This research will yield the first fault slip rates from right-lateral (dextral) faults using modern geologic techniques collected over multiple time scales on these faults. The results will bracket the timing of dextral faulting and will result in more accurate fault slip rates during the Quaternary (i.e., from about 2.6 million years to the present-day). The data obtained in this study will aid in developing improved estimates of seismic hazards in the region. In addition to the scientific objectives of the study, the project will contribute to strengthening and diversify the geoscience academic workforce through mentorship of two early career scientists; it will promote interdisciplinary research projects through collaborations among students, faculty, and researchers from multiple institutions; it will contribute to the training of the next generation of scientists by involvement in research and high impact inquiry-based course activities; will disseminate these activities to the teaching community for adoption in their own courses to increase geoscience literacy; and will enhance scientific literacy of the public by developing an outreach program of lectures and online land- and aerial-based videos. The project represents collaboration and partnerships between educational and research institutions of diverse scale and mission, as well as with state and governmental agencies. The principal investigators will investigate the spatial and temporal distribution of faulting and fault kinematics along a set of active northwest-striking dextral faults across the relatively narrow eastern part of the central Walker Lane, Nevada. The research involves an integrated program of geologic mapping including terrestrial laser scanning structural and kinematic studies, and geochronology using 40Ar/39Ar, terrestrial cosmogenic 10Be and 36Cl, and U-series dating. The research is motivated by: ongoing GPS studies of contemporary dextral strain accumulation in the central Walker Lane; geologic studies of dextral strain release across wider zones of deformation in the northern and southern Walker Lane; and proposed changes in the forces driving deformation over time including edge forces (related to changing directions and rates of relative motion between the Pacific and North American plates) and internal forces (increased gravitational potential energy as a consequence of recent uplift of the Sierra Nevada). The Walker Lane is a zone of dextral shear that accommodates approximately 25% of the Pacific-North American relative plate motion that is superimposed on Basin and Range extension. Our proposed research program across the central Walker Lane will yield dextral fault slip rates collected over multiple time scales (millions to thousands) and brackets on the timing of dextral faulting. Documenting the strain release patterns along faults in this part of the Walker Lane will allow the principal investigators to characterize the spatial and temporal patterns of strain release along faults in this part of the Walker Lane. Combining these data with similar geologic studies ongoing elsewhere in the Walker Lane, and studies ongoing throughout the Walker Lane will allow the principal investigators to document the magnitude of strain partitioning among the western and eastern central Walker Lane, the adjacent Basin and Range, and the northern Walker Lane. Examination of these data will allow assessment of whether patterns of strain in the Walker Lane have changed in synchrony with known changes in potential driving forces the western U.S. This project will support the continued development and application of U-series geochronological techniques for dating late Quaternary landforms and deposits. The combination of terrestrial cosmogenic radionuclide and U-series geochronology used in this study will provide a comprehensive evaluation of its application to dating late Quaternary landforms and deposits in the Great Basin that will inform future slip-rate studies in this region and worldwide.

沃克巷是西北走向变形带的一个神秘地带，横跨加利福尼亚州和内华达州边界，长近 700 公里。它的主要特征是西北走向的断层，显示出右旋剪切的证据。沃克巷断层的形成是由于太平洋和北美构造板块相互滑过时相对运动产生的变形所致。本研究的目的是调查内华达州沃克巷中部相对狭窄的东部沿一组活动断层的断层滑动和运动的时空分布。这项研究将利用在多个时间尺度上收集的现代地质技术，从右旋（右旋）断层中获得第一个断层滑动率。结果将确定右旋断层的时间，并得出第四纪期间（即从约 260 万年至今）更准确的断层滑动率。这项研究获得的数据将有助于改进对该地区地震灾害的估计。除了研究的科学目标外，该项目还将通过指导两名早期职业科学家，有助于加强地球科学学术队伍并使其多样化；它将通过多个机构的学生、教师和研究人员之间的合作来促进跨学科研究项目；它将通过参与研究和高影响力的探究课程活动，为下一代科学家的培训做出贡献；将向教学界传播这些活动，以便在他们自己的课程中采用，以提高地球科学素养；并将通过制定讲座和在线陆基和空中视频的外展计划来提高公众的科学素养。该项目代表了不同规模和使命的教育和研究机构以及州和政府机构之间的合作和伙伴关系。主要研究人员将调查内华达州沃克巷中部相对狭窄的东部沿一组活跃的西北走向的右旋断层的断层活动和断层运动学的时空分布。该研究涉及地质测绘综合计划，包括陆地激光扫描结构和运动学研究，以及使用 40Ar/39Ar、陆地宇宙成因 10Be 和 36Cl 以及 U 系测年的地质年代学。该研究的动机是：正在进行的关于沃克巷中部当代右旋应变积累的 GPS 研究；对沃克巷北部和南部更广泛的变形区域右旋应变释放的地质研究；并提出随着时间的推移驱动变形的力的变化，包括边缘力（与太平洋和北美板块之间相对运动的方向和速率的变化有关）和内力（由于最近内华达山脉的隆起而增加的重力势能） 。沃克巷是一个右旋剪切带，容纳了叠加在盆地和山脉延伸上的约 25% 的太平洋-北美相对板块运动。我们提出的跨沃克巷中部的研究计划将产生在多个时间尺度（数百万到数千）内收集的右旋断层滑移率以及右旋断层发生时间的范围。记录沃克巷这部分断层上的应变释放模式将使主要研究人员能够表征沃克巷这部分断层上应变释放的空间和时间模式。将这些数据与沃克巷其他地方正在进行的类似地质研究以及整个沃克巷正在进行的研究相结合，将使主要研究人员能够记录沃克巷中西部和东部、邻近盆地和山脉以及沃克巷北部。对这些数据的检查将有助于评估沃克巷的应变模式是否与美国西部潜在驱动力的已知变化同步变化。该项目将支持 U 系列地质年代学技术的持续开发和应用，以测定晚第四纪地貌的年代和存款。本研究中使用的陆地宇宙成因放射性核素和 U 系列地质年代学的结合将对其在大盆地晚第四纪地貌和沉积物测年中的应用进行全面评估，从而为该地区和全世界未来的滑移率研究提供信息。