Petrologic Evolution of the Northern Eldorado Mountains, Southern Nevada

位于内华达州南部、亚利桑那州西部和加州东南部的科罗拉多河下游伸展走廊是研究大陆伸展和岩浆活动之间相互作用的理想天然实验室。大多数100%的扩展集中在相当短的时间间隔（1-4百万年）。之后断层活动和火山活动迅速减少。本研究将集中于内华达州北方埃尔多拉多山脉的构造/构造和岩石学演化，那里已经有良好的地质填图、高精度40 Ar/39 Ar地质年代学和构造分析数据库。火山岩在大规模拉张前、拉张中和拉张后的常量元素地球化学变化，可以反映岩浆岩在拉张过程中对下地壳和地幔流变学变化的响应。这一研究结果将直接证明伸展速率与高度伸展大陆岩石中镁铁质岩浆成分变化之间的关系，并将对其他伸展构造环境具有广泛的应用价值。

The lower Colorado River extensional corridor in southern Nevada, western Arizona and southeastern California is an ideal natural laboratory in which to examine the interplay between continental extension and magmatism. Most of the 100% extension was concentrated over a rather short time interval (1-4 m.y.) after which both faulting and volcanism decreased rapidly. This study will focus on the structural/tectonic and petrological evolution of the northern Eldorado Mountains in Nevada, where a good data base of geological mapping, high precision 40Ar/39Ar geochronology and structural analysis already exists. Changes in major element geochemistry in the volcanic rocks erupted before, during and after large-scale extension will show how the magmatic rocks responded to rheological changes in the lower crust and mantle during extension. The results of this study will provide direct documentation of the relationship between rates of extension and changes in the composition of mafic magmas in highly extended continental terranes, and will have wide-reaching application to other extensional tectonic environments.