Zircon in Iceland: Elucidating Generation and Evolution of Silicic Magma and Juvenile Crust

冰岛的锆石：阐明硅质岩浆和新生地壳的生成和演化

• 批准号: 1220523
• 负责人: Calvin Miller
• 金额: $ 33.29万
• 依托单位: Vanderbilt University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1220523&HistoricalAwards=false
• 关键词: Zircon; Iceland; Elucidating; Generation; Evolution

The 2010 eruption of Eyjafjallajökoll, which paralyzed international air traffic, called attention to Iceland?s geological uniqueness and potential global impact. Both the explosive behavior of its many active volcanoes and the plentiful geothermal energy resources that power the clean island nation are linked to unusual oceanic magma systems that yield abundant silicic lava, ash, and granitic rocks. This project emphasizes the mineral zircon as a tracer to explore the processes operating in Iceland at present and in the past to generate silicic magmas, build a continent-like island in the mid-Atlantic, and power its dynamic volcanic and geothermal systems. Iceland?s size and the thickness of its crust, as well as its copious silicic magmatism, make it unique among Earth?s oceanic islands. These characteristics have led previous researchers to propose that the island provides a modern example of the early stages of formation of permanent, low-density continental crust, perhaps mimicking the initiation of the first continents over four billion years ago. Notably lacking in the extensive studies of Icelandic geology are investigations of zircon, which have elsewhere provided the underpinnings for much of our understanding of magmatic processes and the origin and evolution of the Earth?s crust. Zircon, a mineral typically associated with the silicic rocks of continents and island arcs, is the most durable and reliable material for radiometric dating of high-temperature processes and at the same time provides information about the environments in which it grows. Although a majority of Iceland?s crust is low in silica (basalt) and therefore poor in zircon, the island's higher-silica rocks (granite and rhyolite) carry sufficient zircon to elucidate its history. This investigation builds on pilot studies by the investigators using radiometric dating and elemental and isotopic compositions of zircon to clarify the processes by which silicic magmas are generated in Iceland and stored and modified prior to eruption. The research will refine understanding of how magmatic and related geothermal systems work in Iceland. In so doing, it will also address issues of evolving climate (did the change from temperate to glacial conditions affect magmatic processes?) and tectonic construction of Iceland (what roles do rifting and plume processes play in production of silicic magma?; is Iceland underlain by fragments of ancient continental crust that remain from the opening of the Atlantic?).

2010年Eyjafjallajökoll火山爆发，导致国际空中交通瘫痪，人们开始关注冰岛。美国的地质独特性和潜在的全球影响。它的许多活火山的爆炸行为和为这个清洁的岛国提供动力的丰富的地热资源都与产生丰富的硅熔岩、火山灰和花岗岩的不寻常的海洋岩浆系统有关。该项目强调矿物锆石作为示踪剂，探索冰岛现在和过去产生硅岩浆的过程，在大西洋中部建造一个类似大陆的岛屿，并为其动态火山和地热系统提供动力。冰岛?它的大小和地壳的厚度，以及丰富的硅质岩浆活动，使它在地球上独一无二。大洋岛屿。这些特征使先前的研究人员提出，该岛提供了永久低密度大陆地壳形成早期阶段的现代例证，可能模仿了40多亿年前第一批大陆的形成。在对冰岛地质的广泛研究中，明显缺乏对锆石的调查，而锆石在其他地方为我们理解岩浆过程和地球的起源和演化提供了基础。地壳。锆石是一种通常与大陆和岛弧的硅质岩石有关的矿物，它是高温过程的辐射定年法中最耐用、最可靠的材料，同时也提供了有关其生长环境的信息。尽管冰岛的大多数？S地壳硅质（玄武岩）含量低，因此锆石含量低，岛上的高硅质岩石（花岗岩和流纹岩）携带足够的锆石来说明其历史。这项调查建立在研究人员利用放射性测年法和锆石元素和同位素组成进行的初步研究的基础上，以澄清冰岛硅岩浆在喷发前产生、储存和修改的过程。这项研究将完善对冰岛岩浆和相关地热系统如何工作的理解。在此过程中，它还将解决气候演变问题（从温带到冰川条件的变化是否影响了岩浆过程？）和冰岛的构造构造问题（裂谷和羽流过程在硅岩浆的产生中起什么作用？冰岛是否被大西洋打开后遗留下来的古代大陆地壳碎片所覆盖？）