Collaborative Research: Testing the Existence of Magma Mush Zones and Potential Processes of Magma Differentiation in the Mid-crust with In situ Mineral Geochemistry

对大陆边缘火山下岩浆管道系统的详细了解对于理解大陆地壳的演化和生长及其对地壳变形和矿床形成的相关影响至关重要。了解岩浆管道系统过程的时间和长度尺度，有助于揭示火山喷发的空间分布、类型和频率及其相关危害。尽管我们对大陆边缘岩浆作用的认识在深度上有了很大的提高，但关于次火山岩浆储层中大量岩浆的规模，甚至存在与否，岩浆体之间通过大陆地壳厚度的相互联系，以及改变这些岩浆化学性质的过程的重要性和程度，争论仍在继续。这项研究的目的是通过研究在加利福尼亚约塞米蒂国家公园暴露出来的深埋岩体（在深处形成的古代岩浆岩）来调查这些缺失的、但至关重要的谜团。传统的大块岩石元素和同位素分析留下了太多关于地壳岩浆系统结构的基本问题，本研究通过对岩体中单个晶体进行微观地球化学分析的新方法来解决这些问题。该研究还将为数值模拟工作提供更好的数据，并具有指导未来深部岩石研究的巨大潜力。本研究将采用纹理约束、元素和同位素地球化学分析方法，对图伦侵入杂岩战略选择地点的组成非均质造岩和辅助矿物进行分析。它曾经是一个复合的，中地壳弧岩浆库，来测试以下假设。(1)深部岩体的矿物分带和包裹体关系记录了清晰、可解读的岩浆历史。(2)中地壳储层中存在相互连通的岩浆浆液带。(3)深部注入岩浆与共存的泥状岩浆带之间发生了富晶岩浆的混合作用。(4)晶液分离是中地壳的重要过程；因此，许多深成岩是堆积的，并不代表液体成分。验证这些假设将有助于评估中地壳弧深岩体的两种模型。一个岩脉模型预测岩浆在地壳深处获得它们的化学特征。热区域?并迅速上升到次火山储层，而不产生大的岩浆体。岩浆泥柱模型预测，岩浆形成垂直分布广泛的储层，并在许多地壳水平上经历成分改变。矿物分析将有助于识别不同的矿物种群，解释普遍的岩浆过程，评估同时期岩浆的存在与否及其尺寸，以及这些岩浆化学“交流”的能力。

Detailed knowledge of magma plumbing systems beneath continent-margin volcanoes is crucial for understanding the evolution and growth of continental crust and the associated effects on crustal deformation and ore deposit formation. Understanding the time and length scales of processes in the magma plumbing system sheds light on the spatial distribution, type and frequency of volcanic eruptions and associated hazards. Although our understanding of continent-margin magmatism at depth is vastly improving, debate continues as to the dimensions, and even existence, of large magma volumes in sub-volcanic magma reservoirs, the interconnectivity between magma bodies through the thickness of the continental crust, and the importance and extent of processes that modify the chemistry of such magmas. The aim of this study is to investigate these missing, but critical pieces of the puzzle through study of plutons - ancient magmatic rocks formed at depth - as exposed in Yosemite National Park, California. Traditional bulk-rock element and isotope analyses have left too many fundamental questions about the architecture of crustal magmatic systems, resolution of which is a goal of this study through a new approach of utilizing micro-scale geochemical analysis of individual crystals in plutons. This research will also provide better data for numerical modeling efforts and has great potential to guide future studies of plutonic rocks.This study will use texturally-constrained, element and isotope geochemical analysis of compositionally heterogeneous rock-forming and accessory minerals from strategically selected sites of the Tuolumne Intrusive Complex ? which was once a composite, mid-crustal arc magma reservoir - to test the following hypotheses. (1) Mineral zoning and inclusion relationships in plutonic rocks record distinct, decipherable magmatic histories. (2) Interconnected magma mush zones exist in mid-crustal reservoirs. (3) Mixing of crystal-rich magmas occurs between magmas injected from deeper levels and coexisting mush zones. (4) Crystal-liquid separation is an important process in the middle crust; consequently, many plutonic rocks are cumulate and do not represent liquid compositions. Testing these hypotheses will allow assessment of two models for mid-crustal arc plutons. A dike model predicts that magmas attain their chemical signatures in deep-crustal ?hot zones? and rise rapidly to sub-volcanic reservoirs without producing large magma bodies. A magma mush column model predicts that magmas form vertically-extensive reservoirs and undergo compositional modification at many crustal levels. Mineral analysis will allow identification of distinct mineral populations, interpretation of prevalent magmatic processes, assessment of the presence or absence of coeval magmas and their dimensions, and the ability of such magmas to chemically ?communicate?.