the eastern Snake River Plain , Idaho Extension-driven right-lateral shear in the Centennial shear zone adjacent to
the eastern Snake River Plain , Idaho Extension-driven right-lateral shear in the Centennial shear zone adjacent to
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东部斯内克河平原，爱达荷州延伸驱动的百年剪切带右旋剪切
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发表时间：
2013
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通讯作者：
S. Kattenhorn
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作者：
S. Payne;R. Mccaffrey;S. Kattenhorn
利用全球定位系统（GPS）的地表速度和重力势能（GPE）变化来评估百年剪切带（位于伸展的百年构造带（蒙大拿-爱达荷州）和东部蛇河平原（爱达荷州）火山地形之间的ne向调节带）右侧剪切的原因。对假设的“书架”断裂模式进行了验证，发现百年构造带的正断层不适合分布的右旋剪切。相反，GPS数据显示，百年构造带的快速伸展与斯内克河平原的缓慢变形区域相邻，推动了它们之间以0.3-1.5毫米/年的速度进行的右侧剪切。百年构造带由于地势较高，GPE变化支持重力坍缩的速率高于蛇河平原东部，后者由于地势较低，地形平坦，地壳成分较致密，GPE变化较小。在40 - 45公里宽的百年剪切带观测到的地表速度梯度显示了由于走滑断裂、分布的简单剪切、区域尺度的旋转或它们的某种组合而造成的分布变形。在百年剪切带中，横向剪切速度最快的是最靠近黄石高原的地方，在东北向的地震活动性带中记录了带右侧走滑分量的断平面解。在这里，两条盆地和山脉正断层沿其段有全新世和晚更新世的滑动，这表明它们可能在右侧剪切作用下相互连接。我们还认为，在现有的ne向断裂上可能容纳右侧走滑运动。岩石圈GSA数据存储库项目2013226 doi:10.1130/L200.1复制许可，请联系editing@geosociety.org |©2013美国地质学会doi:10.1130/L200.1岩石圈，于2013年6月3日在线发布
We evaluate global positioning system (GPS) surface velocities and gravitational potential energy (GPE) variations to assess the causes of right-lateral shear in the Centennial shear zone, a NE-trending accommodation zone between the extensional Centennial tectonic belt (Montana-Idaho) and volcanic terrain of the eastern Snake River Plain (Idaho). We test the hypothesized “bookshelf” faulting model and fi nd that the normal faults in the Centennial tectonic belt do not accommodate distributed dextral shear. Instead, GPS data reveal that rapid extension in the Centennial tectonic belt adjacent to the much more slowly deforming region of the Snake River Plain drives right-lateral shear between them at rates of 0.3–1.5 mm yr–1. GPE variations support gravitational collapse at a higher rate in the Centennial tectonic belt due to higher topography than in eastern Snake River Plain, which has lower GPE variations due to its low-relief, fl at topography and a denser crustal composition. Surface velocity gradients observed in GPS data across the 40–45-km-wide Centennial shear zone reveal distributed deformation due to strike-slip faulting, distributed simple shear, regional-scale rotation, or some combination thereof. In the Centennial shear zone, the fastest lateral shearing is closest to the Yellowstone Plateau, where fault plane solutions with components of right-lateral strike slip are documented within a NE-trending zone of seismicity. Here, two Basin and Range normal faults have Holocene and late Pleistocene slip along their segments that suggest they each may have linked under right-lateral shear. We also propose that right-lateral strike-slip motion may be accommodated on existing NE-trending faults. LITHOSPHERE GSA Data Repository Item 2013226 doi: 10.1130/L200.1 For permission to copy, contact editing@geosociety.org | © 2013 Geological Society of America as doi:10.1130/L200.1 Lithosphere, published online on 3 June 2013