Collaborative Research: Neotectonics and Structural Development of the Northern Walker Lane

合作研究：沃克巷北部的新构造学和构造发展

• 批准号: 1419724
• 负责人: Steven Wesnousky
• 金额: $ 45.56万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 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=1419724&HistoricalAwards=false
• 关键词: Collaborative; Research; Neotectonics; Structural; Development

The Walker Lane is a major element of the North American-Pacific plate boundary. This northwest trending zone of discontinuous active faults and disrupted topography that sits between the Sierra Nevada on the west and the north-northeast trending faults and ranges of the Great Basin to the east is associated with a well-defined zone of northwest-directed right-lateral shear based on GPS data. The Walker Lane has been suggested to mark the future site of the primary plate boundary thus research on the zone is fundamental to gaining an understanding of how a transform fault initiates and eventually becomes organized into a through-going plate boundary. This project focuses on a portion of northern Walker Lane in western Nevada where geologic evidence of this right-lateral shear is not evident and there is a discrepancy between geologic and GPS measurements of slip rate. LiDAR, geochronologic, and paleomagnetic data collected in this study are used to resolve this mismatch, detect unrecognized faults, and test if rotation of crustal blocks accommodates shear zone motion. The societal and scientific impact of the research will be enhanced by inclusion of both high school and undergraduate science students in the proposed research. The results will aid in assessment of seismic hazards in the Reno-Carson City corridor.This project focuses on the portion of the Walker Lane in Nevada that encompasses the Lake Tahoe, Carson, Smith, Mason, Antelope, Bridgeport and Walker Lake basins and Carson and Wabuska structural lineaments. Here, geodetic data indicate ongoing northwest directed right-lateral shear strain is accumulating at about 5 to 6 mm/year and cumulative shear displacement of 20-30 km has enigmatically resulted in the development of a set of roughly en echelon normal fault-bounded basins in the absence of any major northwest-directed strike-slip faults. This project will collect and analyze LiDAR for evidence of strike-slip along the major structures of the region, apply cosmogenic, optically stimulated luminescence, and radiocarbon dating to identified offset surfaces to better quantify the rate at which faults are slipping, and utilize gravity and paleomagnetism to clarify the long-term structural development of the basins. The project will test the hypothesis that the displacement field across the region is taken up by a combination of vertical-axis rotations, southeastward translation of crustal blocks approximately parallel to the Walker Lane, and opening of the en-echelon set of basins. The goals of the research are to: (1) locally clarify whether or not the mismatch in geodetic rates is real, (2) assess whether or not the blocks bounding the basins record rotation and, if so, related to observed basin asymmetry, (3) compare the collected observations in the framework of prior hypotheses concerning the structural development of this portion of the Walker Lane, and (4) and integrate the mode of deformation observed here to elsewhere in the Walker Lane and the San Andreas fault system with an aim toward understanding the processes associated with the structural initiation of a continental strike-slip fault system.

沃克巷是北美-太平洋板块边界的主要组成部分。这个西北走向的断裂带和破碎的地形位于内华达山脉西部和东北偏北走向的断裂带和大盆地东部之间，根据GPS数据，这个断裂带与一个明确的西北走向的右侧剪切带有关。沃克巷被认为是未来主要板块边界的标志，因此对该带的研究对于理解转换断层如何开始并最终组织成贯穿的板块边界是至关重要的。该项目的重点是内华达州西部Walker Lane北部的一部分，该地区右侧剪切的地质证据并不明显，并且地质和GPS测量的滑移率之间存在差异。本研究中收集的激光雷达、地质年代学和古地磁数据用于解决这种不匹配，检测未识别的断层，并测试地壳块体的旋转是否适应剪切带运动。研究的社会和科学影响将通过包括高中和本科理科学生在拟议的研究中得到加强。研究结果将有助于评估里诺-卡森市走廊的地震危险性。该项目重点关注内华达州沃克巷的一部分，包括太浩湖、卡森湖、史密斯湖、梅森湖、羚羊湖、布里奇波特湖和沃克湖盆地，以及卡森湖和瓦布斯卡湖的构造轮廓。在这里，大地测量数据表明，在没有任何主要的西北走向走滑断层的情况下，正在进行的西北方向的右侧剪切应变以大约5至6毫米/年的速度累积，20-30公里的累积剪切位移神秘地导致了一组大致呈雁梯队状的正断层边界盆地的发展。该项目将通过激光雷达收集和分析该地区主要构造的走滑证据，应用宇宙成因、光激发光和放射性碳定年技术来确定偏移面，以更好地量化断层滑动的速度，并利用重力和古地磁来阐明盆地的长期构造发展。该项目将测试一个假设，即整个地区的位移场是由垂直轴旋转、大致平行于沃克巷的地壳块体向东南平移以及雁梯队盆地开放的组合所占据的。研究的目标是：(1)局部澄清大地测量速率的不匹配是否真实；(2)评估盆地边界块是否记录了旋转，如果有，是否与观测到的盆地不对称有关；(3)在先前关于沃克巷这部分构造发育的假设框架内比较收集到的观测结果。(4)将这里观察到的变形模式与沃克巷和圣安德烈亚斯断层系统的其他地方相结合，目的是了解与大陆走滑断层系统的构造起源相关的过程。