Timing of Intracontinental Deformation across the Eastern Mono Basin, California and Nevada

北美板块和太平洋板块之间的现代变形分布在北美西部从圣安德烈亚斯断层向东到西部盆岭省的广阔区域。东部的莫哈韦沙漠和内华达州和大盆地之间的地区形成了一个分布变形带，容纳了太平洋和北美板块之间约25%的相对运动。南部的变形位于东加州剪切带内，北部位于步行者车道带内，该车道带的特征是西北走向的断层，其地震震源机制和GPS速度指示了张扭变形。本项目测试的假设是，早中新世至中中新世期间与扭张系统相关的变形位于莫诺盆地地区的内华达州山脉前缘以东，然后在晚中新世向东进入米纳偏转。为此，研究小组正在对渐新世至上新世的镁铁质至中等熔岩流、流纹质熔结凝灰岩、莫诺盆地地区（Huntoon山谷、Adobe丘陵、羚羊山脉、Cowtrack山脉）的沉积物进行详细的古地磁研究，以确定垂直轴旋转的空间和时间模式。野外构造研究结合火山岩和侵入岩的40 Ar/39 Ar地质年代学被用来约束断层的几何学、运动学、断层滑动的大小和变形的时间。东加州剪切带和步行者巷带，一个从莫哈韦沙漠延伸到加州北方/内华达州西北部的地带，是重要的断层系统，容纳了北美和太平洋板块之间的大部分运动，其中大部分运动由圣安德烈亚斯断层承担。然而，这个复杂的断裂带的构造演化仍然知之甚少。该项目旨在解决这个难题的一个重要部分，因为它将有助于更好地理解变形如何随着时间的推移而变化。该项目有学生参与的重要组成部分。提高学生的技术和基础科学技能将培训和促进少数民族和代表性不足的学生的研究工作。

Modern deformation between the North American and Pacific plates is distributed across a wide zone of western North America from the San Andreas fault eastward into the western Basin and Range Province. The eastern Mojave Desert and the region between the Sierra Nevada and Great Basin form a zone of distributed deformation that accommodates about 25 percent of the relative motion between the Pacific and North American plates. Deformation to the south is localized within the Eastern California Shear Zone and to the north in the Walker Lane Belt, which today is characterized by northwest-trending faults with associated earthquake focal mechanisms and GPS velocities that are indicative of transtensional deformation. This project tests the hypothesis that deformation associated with the transtensional system during the early to mid-Miocene was located east of the Sierra Nevada front in the area of the Mono Basin prior to stepping east into the Mina Deflection in the late Miocene. To do so the research team is carrying out a detailed paleomagnetic study of the Oligocene to Pliocene mafic to intermediate lava flows, rhyolitic ignimbrites, sediments in the Mono Basin area (Huntoon Valley, Adobe Hills, Antelope Mountains, Cowtrack Mountains) to determine the spatial and temporal patterns of vertical axis rotation. Field structural studies coupled with 40Ar/39Ar geochronology of volcanic and intrusive rocks are used to constrain the fault geometry, kinematics, magnitude of fault slip, and the timing of deformation.The Eastern California Shear Zone and Walker Lane Belt, a zone that stretches from the Mojave Desert to northern California/northwestern Nevada, are important fault systems that accommodate a substantial portion of the motion of between the North American and Pacific plates, with most of the motion taken up by the San Andreas fault. However, the tectonic evolution of this complex fault zone remains poorly understood. This project aims to resolve an important part of the puzzle in that it would contribute to a better understanding of how deformation shifts through time. The project has a significant component of student involvement. Improving students' technological and basic science skill-sets will train and foster research endeavors for minority and underrepresented students.