RUI: Mechanisms of Hybridization in Silicic Magma Chambers Affected by Mafic Injections and Their Imprint on Granite: The Vinalhaven Magmatic Complex, coastal Maine

RUI：受镁铁质注入影响的硅质岩浆房的杂交机制及其在花岗岩上的印记：缅因州沿海的维纳尔黑文岩浆杂岩

• 批准号: 0003555
• 负责人: David Hawkins
• 金额: $ 10.44万
• 依托单位: Denison University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0003555&HistoricalAwards=false
• 关键词: RUI; Mechanisms; Hybridization; Silicic; Magma

Wiebe/HawkinsEAR-0003260/0003555The goal of this project is to investigate how the injection of mafic magma into a shallow silicic magma chamber affects the chemical and isotopic composition of rocks preserved in granite plutons. The Vinalhaven pluton is an ideal setting for this study because mafic input to a silicic magma chamber is well preserved in feeders and as layered deposits of mafic and hybrid intermediate to silicic rocks. These rocks provide a spatial and temporal framework that will permit us to evaluate the petrographic, geochemical, and isotopic signature of hybridization both proximal and distal to the point of entry of the individual mafic replenishments, as well as in the overlying "homogeneous" granite. Our work will focus on intragrain trace element and isotopic variations through microanalysis of selected minerals, using laser ablation ICPMS and ID-TIMS. We will also employ high-precision U-Pb geochronology to constrain the active lifetime of the Vinalhaven magma chamber and attempt to link the preserved magmatic record to the preserved eruptive record of genetically related volcanic rocks. In the first year, this project will incorporate a Keck Geology Consortium Project with nine undergraduates who will undertake 4 weeks of field work. This research bears directly on the origin and emplacement of granite. We believe that studies of mineral zoning are likely to show that adjacent crystals have very different histories of crystallization. This information, combined with the common isotopic variability of a granite and field evidence for multiple replenishments of diverse magmas, strongly suggests that the bulk chemical and isotopic compositions of granite are neither the records of a single magma source nor equivalent to volcanic liquids erupted from the chamber.

Wiebe/Hawkinsert-0003260/0003555该项目的目标是研究镁铁质岩浆注入浅部岩浆房如何影响花岗岩岩体中保存的岩石的化学和同位素组成。 Vinalhaven岩体是一个理想的设置为这项研究，因为基性岩输入到一个岩浆房保存完好的馈线和层状矿床的基性岩和混合中间到辉长岩。 这些岩石提供了一个空间和时间的框架，将使我们能够评估的岩相，地球化学和同位素的杂交签名的近端和远端的个人镁铁质沉积物的入口点，以及在上覆的“同质”花岗岩。 我们的工作将集中在晶粒内微量元素和同位素的变化，通过微分析选定的矿物，使用激光烧蚀ICPMS和ID-TIMS。我们还将采用高精度的U-Pb地质年代学来限制Vinalhaven岩浆房的活动寿命，并试图将保存的岩浆记录与保存的火山岩喷发记录联系起来。在第一年，该项目将包括一个凯克地质联合会项目，9名本科生将进行为期4周的实地考察。 这一研究直接关系到花岗岩的成因和侵位。我们相信，矿物环带的研究很可能表明，相邻的晶体有非常不同的结晶历史。 这一信息，结合常见的同位素变化的花岗岩和现场证据的多个不同的岩浆，强烈表明，大部分的化学和同位素组成的花岗岩既不是一个单一的岩浆源的记录，也不等同于火山液体从房喷发。