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

点击翻译按钮获取中文摘要

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.