Middle Tertiary Magmatism in East Central Nevada

本项目将利用内华达州中东部大量中第三纪、中至硅质火山活动的岩石学框架作为基础：(1)通过完成卡拉马祖凝灰岩的分带工作，研究在系统演化过程中瞬间作用的岩石学过程；(2)详细分析了该体系初始、高潮和衰亡时期的同位素和结构变化；(3)演化中的岩浆系统的质量和热收支的发展。内华达州中东部的岩石特别适合这项研究，因为它们代表了大量（数千立方公里）的含金属岩浆，其侵入物可能是典型的“钙碱性”基。并对其年龄、结构、矿物学、主元素、微量元素、同位素组成等特征进行了分析，与岩浆系统的三阶段演化相一致。

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.