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

2010 年埃亚菲亚德拉火山喷发导致国际空中交通瘫痪，引起人们对冰岛地质独特性和潜在全球影响的关注。 许多活火山的爆发行为和为这个清洁岛国提供动力的丰富地热能源都与不寻常的海洋岩浆系统有关，这些岩浆系统产生丰富的硅质熔岩、火山灰和花岗岩。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质岩浆的过程，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。冰岛的面积和地壳厚度，以及丰富的硅质岩浆作用，使其在地球上的海洋岛屿中独一无二。 这些特征使得之前的研究人员提出，该岛提供了永久低密度大陆地壳形成早期阶段的现代例子，可能模仿了四十亿多年前第一块大陆的形成。 冰岛地质学中明显缺乏对锆石的广泛研究，而锆石在其他地方为我们对岩浆过程以及地壳起源和演化的理解提供了基础。 锆石是一种通常与大陆和岛弧的硅质岩石相关的矿物，是用于高温过程放射性测年的最耐用、最可靠的材料，同时提供有关其生长环境的信息。 尽管冰岛大部分地壳的二氧化硅（玄武岩）含量较低，因此锆石含量也较低，但岛上的高硅质岩石（花岗岩和流纹岩）含有足够的锆石来阐明其历史。 这项调查建立在研究人员利用放射性测年以及锆石的元素和同位素组成进行试点研究的基础上，以阐明冰岛硅质岩浆的生成过程以及在喷发前储存和改变的过程。 该研究将加深对冰岛岩浆和相关地热系统如何运作的理解。 在此过程中，它还将解决气候演变的问题（从温带条件到冰川条件的变化是否影响岩浆过程？）和冰岛的构造构造（裂谷和羽流过程在硅质岩浆的产生中发挥什么作用？冰岛下面是否有大西洋开口时残留的古代大陆地壳碎片？）。

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?).