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.

步行者巷是北美-太平洋板块边界的主要组成部分。位于西部的Sierra内华达州和东部的大盆地的北-东北走向断层和范围之间的不连续活动断层和中断地形的西北走向区域与基于GPS数据的西北定向右侧剪切的明确区域相关。步行者巷已被建议标志着未来的网站的主要板块边界，因此，对该地区的研究是根本的，以获得一个转换断层如何启动，并最终成为组织成一个贯穿的板块边界的理解。本项目的重点是内华达州西部北方步行者巷的一部分，在该部分，右向剪切的地质证据并不明显，并且滑动速率的地质和GPS测量值之间存在差异。在这项研究中收集的激光雷达，地质年代学和古地磁数据被用来解决这种不匹配，检测未识别的故障，并测试地壳块体的旋转是否适应剪切带运动。这项研究的社会和科学影响将通过将高中和本科理科学生纳入拟议的研究来加强。该项目的重点是内华达州步行者巷的一部分，包括太浩湖、卡森、史密斯、梅森、羚羊、布里奇波特和步行者湖盆地以及卡森和瓦布斯卡构造线。在这里，大地测量数据表明，正在进行的西北方向的右行剪切应变积累约5至6毫米/年，累计剪切位移20-30公里，神秘地导致了一组大致雁行正断层为界的盆地的发展，没有任何主要的西北方向的走滑断层。该项目将收集和分析LiDAR，以获得该地区主要构造沿着走滑的证据，将宇宙成因、光激发光和放射性碳测年应用于已确定的偏移面，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。该项目将检验一种假设，即整个区域的位移场是由垂直轴旋转、大致平行于步行者巷的地壳块体向东南平移以及一组梯形盆地的张开所组成的。研究的目标是：（1）局部地澄清大地测量速率的不匹配是否是真实的，（2）评估界定盆地的块体是否记录了旋转，并且如果是，则与观察到的盆地不对称性有关，（3）在关于步行者巷的这一部分的结构发展的先前假设的框架内比较收集到的观测，（4）把这里所观察到的变形模式与步行者巷和圣安德烈亚斯断裂系统的其他地方结合起来，以了解大陆走滑断裂系统的构造启动过程。