Basin and Range Geoscientific Experiment (BARGE)

该项目涉及一项综合的、多学科的研究，以量化大陆地壳深部和最上层地幔对伸展的反应，从而确定岩石圈的大水平应变与均衡控制的垂直运动的关系。主要研究人员计划利用“自然实验”，在岩石圈的最上部与高度扩展的地形和构造稳定的块体之间的突然边界有关的一个大应变梯度。他们选择了科罗拉多高原的西部边缘进行研究。它非常适合完成他们的研究目标，有几个原因：(1)这里的过渡特别突然；(2)地质背景为简单的伸展前地壳构造；(3)具有很好的大规模伸展运动史；(4)米德湖的大型内陆水道为进行深入的地球物理研究提供了独特的环境，这些研究可以精确地在地质研究中对伸展过程中地壳隆起的边界进行横切。他们建议将地质和地质年代学研究、湖泊本身的“海洋”多通道地震反射剖面与陆地上的三分量地震仪阵列记录结合起来，以控制地震速度结构并开发该地区的层析成像图像。再加上重力模型，他们就能解开岩石圈对严重拉伸应变反应的运动学和动力学。

This project involves an integrated, multi-disciplinary investigation to quantify how the deep continental crust and uppermost mantle respond to extension, and to thus establish how large horizontal strains of the lithosphere relate to vertical motions controlled by isostasy. The principal investigators plan to use the "natural experiment" of a large strain gradient in the uppermost part of the lithosphere associated with the abrupt boundary between highly extended terrain and a tectonically stable block. They have chosen the western margin of the Colorado Plateau to study. It is ideally suited for accomplishing their research objectives for several reasons: (1) the transition is particularly abrupt here; (2) the geologic setting indicates a simple pre- extensional crustal structure; (3) it has a well-understood large- scale extensional kinematic history; (4) the large inland waterway of Lake Mead provides a unique environment in which to perform deep geophysical studies that transect the boundary in precisely the location where geological studies place bounds on crustal uplift during extension. They propose to integrate geological and geochronologic studies, "marine" multi-channel seismic reflection profiling in the lake itself, integrated with land-based recordings on an array on three-component seismometers to provide control on seismic velocity structure and to develop tomographic images of the region which, together with gravity modeling will allow them to unravel the kinematics and dynamics of the lithosphere's response to severe extensional strain.