Collaborative Research:Processing Magma and Constructing Plutons in the Upper Crust:Insights on Magma Chambers from Top-to-Bottom Views of Plutons and Associated Volcanic Sequences

了解岩浆如何从源头到最终的岩石安息地的旅程是至关重要的理解地壳演化，岩浆上升和就位的力学及其与构造的关系，和喷发过程。 上地壳岩浆房中的储存一直是，现在仍然是这段旅程中大多数观点的核心。 然而，近年来，岩浆房的概念，发生在其中的过程，以及它与最终构造的岩体的关系已经被强烈地重新评估。 许多被广泛接受的观点（例如，岩浆房在其大部分“生命周期”中大多是缺乏晶体的岩浆体）受到了质疑。 我们建议调查内华达州的埃尔多拉多山脉和高地山脉中异常暴露的岩体和可能的等效火山序列的演化，并测试有关岩浆进入，驻留，现有的数据，包括一般的绘图和一个相当大的数据集的40 Ar/39 Ar年龄和整个-岩石元素和同位素分析为这一研究提供了良好的初步基础。 我们将增加现有的数据库，但我们的主要重点将是更新的传统方法和新方法的结合（非常详细的内部岩体结构绘图;详细的岩相学使用成分成像强调分区，反应结构和辅助矿物特征;晶体粒度分布分析;原位铅和锶同位素分析的长石;离子探针测年的锆石）。 这种方法将阐明这些岩浆房的演化，包括它们的填充和补充;内部和外部过程（如对流，质量浪费，顶板坍塌和喷发）的破坏和重新排列;以及最终的岩体构造。 它还将使我们能够通过比较输入岩浆、输出（喷发的岩浆）和保留的物质（冥王星）来评估岩浆房的过滤效果，并限制喷发触发因素和喷发风格的控制。

MillerEAR-0107094Understanding how magma is processed on its journey from source to final rocky resting place is vital for understanding crustal evolution, the mechanics of magma ascent and emplacement and their relation to tectonics, and eruptive processes. Storage in upper crustal magma chambers has been, and still is, central to most views of this journey. However, concepts of the magma chamber, the processes that occur within it, and its relationship to plutons that are ultimately constructed have been intensely reevaluated in recent years. Many widely held views (e.g. that magma chambers are mostly crystal-poor bodies of magma throughout most of their "lifespan") have been called into question. We propose to investigate the evolution of exceptionally exposed plutons and probable equivalent volcanic sequences in the Eldorado Mountains and Highland Range, Nevada, and to test hypotheses about the mechanical and chemical processing of magma as it enters, resides in, and is extracted from magma chambers.Existing data that include general mapping and a sizable data set of 40Ar/39Ar ages and whole-rock elemental and isotopic analyses provide a sound initial basis for this study. We will add to the existing data base, but our main emphasis will be on a combination of updated traditional and new methods (very detailed mapping of internal pluton structures; detailed petrography using compositional imaging to emphasize zoning, reaction textures, and accessory mineral features; crystal size distribution analysis; in situ Pb and Sr isotope analysis of feldspars; ion probe dating of zircon). This methodology will clarify the evolution of these magma chambers, including their filling and replenishment; disruption and rearrangement by internal and external processes such as convection, mass wasting, roof collapse, and eruption; and, ultimately, pluton construction. It will also permit us to evaluate the filtering effect of magma chambers by comparing input magmas, outputs (erupted magmas), and retained materials (plutons), and to constrain eruptive triggers and controls of eruptive styles.