Collaborative Research: A Late Cenozoic Record of Restraining Bend Initiation and Evolution along the Denali Fault at Mount McKinley, Alaska

该项目以阿拉斯加Denali断层的Mount McKinley抑制弯曲为目标，旨在研究结构滑动率与区域挖掘率之间的联系，以及抑制弯曲如何在应变分割的挤压系统中形成和演变。北美最高的山，麦金利山（6196米），位于迪纳利断层地图上17度弯曲的内部。在德纳里断裂带的北部，在这个弯道的外面，最高点是彼得圆顶（3221米），从德纳里断裂带向北不到15公里处的一个沉积盆地，海拔迅速下降。这种地形的不对称性表明，构造对局部发掘模式有很强的控制作用，这种抑制性弯曲在数百万年来对区域造山发育起着主要的控制作用。该研究将采用多温度计方法，结合断层模式和滑动率的新构造/结构分析，来限制麦金利山抑制弯曲的挖掘率和时间。研究人员将采用放射性碳、光激发发光和原位地球宇宙形成核素表面暴露测年技术，为研究区域的主要变形地貌提供年龄控制。此外，该研究的见解将与沿其他走滑断层的复杂断层几何形状的演化以及地质记录中对短暂和持续隆升/挖掘现象的认识进行比较。世界上主要的大陆内走滑断层在相对较短的距离内表现出断层几何形状的突变，通常以断层段之间的弯曲或台阶带的形式出现。这些构造复杂的断层带通常与断层附近明显的隆起或沉降有关。在这些复杂的断裂带中，沿更广泛的走滑系统的水平位移是如何划分为水平和垂直分量的，这是构造学研究的一个重点。特别是，由于沿走滑断层的断层几何形状的变化而产生的收缩带（即抑制弯曲）需要在断层附近发生明显的变形，以便地壳沿着长期水平运动的路径继续运动。因此，这些带似乎会向直断层段演化，但抑制弯曲仍然存在。为迪纳里断裂带及其邻近断裂带开发新的滑动速率数据，将为了解现代构造格局提供关键见解，并约束拟议的地壳块体的潜在边界。此外，该研究的见解将：1)允许与其他走滑断层（如圣安德烈亚斯断层和阿尔卑斯断层）的结构复杂性进行比较；2)有助于进一步了解大陆地壳广泛变形带内的地壳块体如何相互作用3)有助于识别地质记录中短暂和持续的隆升/挖掘现象。研究小组将与阿拉斯加州费尔班克斯流域学校的教育工作者密切合作，制定教育计划和教材，通过在地教育培养学生对科学的兴趣。通过与德纳里国家公园和自然保护区工作人员的密切合作，将促进通过该项目取得的科学进展的交流。由于在这个地震活跃地区发生了许多以前未知的断层，本研究的结果将对区域地震危险性评估作出重大贡献。

This project targets the Mount McKinley restraining bend of the Denali fault in Alaska in order to examine the linkages between structural slip rates and regional exhumation rates and how restraining bends can form and evolve in a strain-partitioned transpressional system. The highest mountain in North America, Mount McKinley (6,196 m), is situated on the inside of a 17 degree bend in the mapped trace of the Denali fault. North of the Denali fault, on the outside of this bend, the highest peak is Peter's Dome (3,221 m) with elevations rapidly decreasing away from the Denali fault to an aggradational basin less than 15 km to the north. This topographic asymmetry suggests a strong structural control on local exhumation patterns and that this restraining bend has been a primary control on regional orogenic development for several million years. The study will apply a multi-thermochronometer approach to constraining exhumation rates and timing along the Mount McKinley restraining bend in conjunction with a neotectonic/structural analysis of fault patterns and slip rates. The researchers will employ radiocarbon, optically stimulated luminescence, and in-situ terrestrial cosmogenic nuclide surface exposure dating techniques to provide age control for the major deformed landforms in this study area. Furthermore, insights from this study will be compared to the evolution of complex fault geometries along other strike-slip faults and the recognition of transient and persistent uplift/exhumation phenomena in the geologic record.Major intracontinental strike-slip faults around the world exhibit abrupt changes in the fault geometry over relatively short distances, often occurring as bends or step-over zones between fault segments. These zones of complex fault geometry are often associated with significant uplift or subsidence adjacent to the fault. Understanding how the horizontal displacement along the broader strike-slip system is partitioned into horizontal and vertical components in these complex fault zones is an ongoing focus of research in tectonics. In particular, contractional zones (i.e., restraining bends) that result from a change in fault geometry along a strike-slip fault require significant deformation adjacent to the fault for the crust to continue along the path of long-term horizontal motion. Therefore, it would seem that these zones would evolve toward a straight fault segment: yet restraining bends persist. Developing new slip rate data for the Denali fault and adjacent faults will provide key insights into the modern tectonic framework and constrain potential boundaries of proposed crustal blocks. Furthermore, insights from this study will: 1) allow comparison to the structural complexities along other strike-slip faults such as the San Andreas and Alpine faults; 2) help further understanding of how crustal blocks interact within broad deforming zones of continental crust 3) aid the recognition of transient and persistent uplift/exhumation phenomena in the geologic record. The research team will work closely with educators at the Watershed School in Fairbanks, Alaska, to develop educational plans and materials to foster student interest in science through place-based education. The communication of the scientific advances made through this project will be promoted through close collaboration with Denali National Park and Preserve staff. With numerous previously unknown faults occurring in this seismically-active region, results from this study will contribute significantly to regional seismic hazard assessments.