Tectonic Processes in Upper Crustal Normal Fault Systems

9628262韦尼克内华达州南维尔京山脉，位于高度延伸的米德湖地区的最东端。我们要求提供资金，以便在内华达州南维尔京山脉完成详细的地质测绘和地质年代学研究。就暴露、地层分辨率、地形起伏和重建的区域基准而言，南维尔京山脉是世界上地壳上叠瓦式正断层结构的最佳范例之一。到目前为止，PI和研究生罗伯特·布雷迪绘制的地图表明，多米诺骨牌风格、滚转铰链和翻滚运动学都可能在系统内活跃，但可能在裂缝走向的不同时间和地点起作用。因此，该地区有可能测试这些模型的适用性，并可能确定一系列倾斜区块中的结构位置如何影响它们的发展。除了地质填图外，我们还建议对选定的样品进行Ar/Ar和U-Th/He测年，以分别确定盆地形成和地块去顶板的绝对年龄。在后一种方法中，矿物磷灰石的闭合温度非常低，约为70oC，这将是He测年在伸展构造问题上的首次应用。

9628262 Wernicke The South Virgin Mountains, Nevada, occupy the easternmost portion of the highly extended Lake Mead region. We request funds for completion of detailed geologic mapping and geochronologic studies in the South Virgin Mountains Nevada. In terms of exposure, stratigraphic resolution, topographic relief and a regional datum for reconstruction, the South Virgin Mountains are among the best examples of upper crustal imbricate normal fault structure in the world. Mapping to date by the PI and graduate student Robert Brady suggests that domino-style, "rolling-hinge," and rollover kinematics are all probably active within the system, but may be operative at different times and places across strike of the rift. Hence the area offers the potential to test the applicability of these models, and possibly determine how structural position within a series of tilted blocks influences their development. In addition to geologic mapping, we propose to complete Ar/Ar and U-Th/He dating of selected samples to establish absolute ages of basin formation and unroofing of the blocks, respectively. In the case of the latter method, which has a uniquely low closure temperature of about 70oC in the mineral apatite, this project will be the first application of He dating to the problem of extensional tectonics.