Collaborative research: Andean Plutonic Perspectives on Generation, Storage, and Eruption of Rhyolite

合作研究：安第斯深成流纹岩生成、储存和喷发的观点

基本信息

批准号：
1650232
负责人：
Bradley Singer
金额：
$ 25.4万
依托单位：
University of Wisconsin-Madison
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-01-15 至 2019-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1650232&HistoricalAwards=false
关键词：
Collaborative research Andean Plutonic Perspectives

项目摘要

Large-scale, caldera-forming volcanic eruptions, for example those characteristic of Yellowstone National Park, owe their explosivity and widespread impact to the composition of molten rock called magma that fuels their plumbing systems. Yet, the generation of such magma plumbing systems, and how the erupted volcanic rock rhyolite is related to the unerupted magma that crystallizes at depth to form plutons of rock called granite that makes up the continental crust which we live on, remains unknown and highly controversial among earth scientists. Our study focuses on the formation of a plutonic body of granite in the southern Andes in Chile that preserves a record of processes required to generate large quantities of potentially explosive volcanic rhyolite. We will map spatially distinct rock types, measure their compositions, and determine the compositions of the constituent minerals that comprise this very young, and exceptionally well-exposed pluton. A multidisciplinary approach using modern geochemical methods, geochronology, and numerical modeling will then be used to interpret the processes, timescales, and thermal history of magma that are preserved in this pluton. We aim to bring the discipline of igneous petrology one step closer to a universal model of magma dynamics that incorporates both the plutonic and volcanic realms.High silica granites are hypothesized to form via crystal-melt fractionation in the shallow crust yet, the resulting crystal residues are rarely identified and can be difficult to distinguish from plutons whose compositions plot along liquid lines of descent. Bulk rock compositional mass balance in the late Miocene Risco Bayo-Huemul plutonic complex in the Southern Andes of Chile suggests that lithological differences reflect crystal concentration in response to melt extraction. We aim to combine field observations with U-Pb petrochronology of zircon and titanite, 40Ar/39Ar thermochronology, compositional and isotopic measurements of whole rocks and minerals within the plutonic complex, and thermal modeling to: (1) establish the rates and mechanisms of emplacement, (2) identify individual magma batches and assess any interaction between them, (3) determine the timescales of crystallization and cooling of individual magma batches and system-wide, (4) establish petrogenetic relationships between the Risco Bayo and Huemul plutons including subdomains within each, and (5) evaluate whether eruptible rhyolitic melt may have formed within this system. This young plutonic complex preserves a detailed record of a process commonly associated with the formation of rhyolite that has propelled large silicic eruptions during the past million years within the adjacent Andean subduction zone.

大规模的，形成火山口的火山喷发，例如黄石国家公园的特征，其爆炸性并广泛影响了称为岩浆的熔融岩石的组成，该岩浆燃料燃烧了他们的管道系统。然而，这种岩浆管道系统的产生以及爆发的火山岩石流纹岩如何与未爆发的岩浆相关，该岩浆在深度上结晶而形成了名为Granite的岩石的岩石，构成了我们所生活的大陆壳，在地球科学家中仍然是未知和高度争议的。我们的研究重点是在智利安第斯山脉南部的安第斯山脉的花岗岩体形成，保留了产生大量潜在爆炸性火山纹状体所需的过程记录。我们将在空间上绘制不同的岩石类型，测量其组成，并确定组成矿物质的组成，这些矿物构成了这种非常年轻且暴露得很好的岩体。然后，将使用现代地球化学方法，地质学和数值建模的多学科方法来解释保留在该柱子中的岩浆的过程，时间表和热历史。我们的目的是将火成岩的纪律带到一个较近的岩浆动力学模型，该模型既包含了岩浆和火山域。假设高二氧化硅花岗岩是通过晶体融化的分馏中形成的，在浅层壳中尚未将晶体残留物与液体形成量很难划分，从而形成了晶体残留物。智利安第斯山脉南部的中新世晚期Bayo-Huemul Plutonic复合物中的大块岩石组成质量平衡表明，岩性差异反映了响应熔体提取的晶体浓度。我们的目的是将现场观察与锆石和钛矿的U-PB石化学结合，40AR/39AR的热量学，组成和同位素测量在岩石络合物中整个岩石和矿物质的测量以及热建模中的整个岩石和矿物质，以及：（1）确定型号的速率和机制，（2）确定型号和机械的机制，（2）识别型号（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）（2）识别出（2）的互动（2）（2）（4）（4）在risco bayo和Huemul Pluton之间建立岩性关系，包括每个子域内的子域，以及（5）评估该系统中是否可能形成可爆发的流纹岩熔体。这种年轻的岩体复合物保留了通常与流纹岩形成相关的过程的详细记录，该过程在过去一百万年内在邻近的安第斯俯冲带中推动了大型硅质喷发。