Middle Tertiary Magmatism in East Central Nevada

该项目将利用内华达州中东部庞大的中第三纪中-硅质火山作用的岩石学格架作为基础：(1)通过完成卡拉马祖凝灰岩的分带工作，研究在系统演化中的瞬间作用的岩石学过程；(2)详细分析系统开始、高潮和衰落期间的同位素和结构变化；以及(3)演化岩浆系统的质量和热平衡的发展。内华达州中东部的岩石特别适合于这项研究，因为它们代表了大量(数千立方公里)的准铝质岩浆，与之相当的侵入岩浆可能是典型的“钙质”岩基。此外，它们的年龄、结构、矿物学、常量元素、微量元素和同位素组成都与岩浆系统的三个阶段的演化相一致。

This project will use the petrologic framework of voluminous, middle Tertiary, intermediate to silicic volcanism in east- central Nevada as a basis for : (1) A study of the petrologic processes acting at an instant in the evolution of the system, by completing work on zonation in the Kalamazoo Tuff; (2) A detailed analysis of isotopic and textural changes during inception, climax, and waning of the system; and (3) Development of a mass and thermal budget of an evolving magma system. The rocks of east-central Nevada are particularly suited for this study because they represent a large volume (thousands of cubic kilometers) of metaluminous magma, the intrusive equivalent of which could be a typical "calcalkaline" batholith. Also, they have been characterized with respect to their age, texture, mineralogy, and major-element, trace-element, and isotopic compositions, all of which are consistent with a three stage evolution of the magmatic system.