SGER: The Owens River as a TIltmeter for Long Valley Caldera: Exploratory Dating of its Oxbow Sediments Using Tephrochronology

长谷的欧文斯河沿着火山口的护城河环绕着复活的圆顶的北部和东部，并显示出地貌证据，表明它的路线已经被圆顶的隆起改变了一段相当长的时间，比过去的十年要长得多。在下游15公里的大部分地区，河流由两条平行的曲流带组成，由一个几乎平面的河间面（200-300米宽）隔开，没有显示出最近河流活动的痕迹。这两个带显示出基本相同的弯曲幅度和波长，但年龄不同。较老的曲流带，现在携带着一个小的不合适的河流，总是比新的外部河道的主流更靠近圆顶，并且海拔高30-60厘米。这条河显然是经过一段时间的横向倾斜后跳入新河道的。河流间表面到河流轴线的投影表明，可能发生了15至35米的总隆起。在欧文斯河最下游的6公里处，洪泛区显示出多达6条可识别的不同年代的曲流带（一些位于现代河道的外侧，另一些位于河道的内侧），这些曲流带似乎记录了下沉和复苏的事件。了解河流在这些曲流带中占据的绝对年龄，可以为我们提供一个圆顶重新出现和下沉的时间估计。我们特别感兴趣的是，火山口北部的Mono陨石坑和Inyo陨石坑的喷发活动是否与欧文斯河通道的迁移行为在时间上有关，从而可能与板条箱底部的复活和下沉有关。

The Owens River at Long Valley follows the caldera's moat around the N and E sides of the resurgent dome and shows geomorphic evidence that its course has been modified by uplift of the dome over a period of time considerably longer than the last ten years. In most of its lower 15km, the river consists of two parallel meander belts separated by a nearly planar interfluvial surface (200-300m wide) that shows no trace of recent river activity. The two belts display essentially identical meander amplitude and wavelength, but are not the same age. The older meander belt, now carrying a small underfit stream, invariably lies closer to the dome than the main flow in the new outboard channel, and sits some 30-60 cm higher in elevation. The river apparently jumped into the new channel after some period of lateral tilting. Projection of the interfluvial surface to the axis of the some suggests that total uplift of 15 to 35 meters may have occurred. In the lowermost six km of its course, the Owens River floodplain shows as many as six identifiable meander belts of different age (some lying outboard and other lying well inboard of the modern channel) that appear to record events of subsidence as well as resurgence. Knowing the absolute ages of the river's occupancy of each of these meander belts may provide us an estimate of the timing of the resurgence and subsidence of the dome. We are particularly interested to know whether eruptive activity in the Mono Craters and Inyo Craters north of the caldera has been tied in a temporal way to the migratory behavior of the Owens River channel, and thus possible to the resurgence and subsidence of the crate floor.