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

2010年，导致国际空中交通瘫痪的埃亚菲亚德拉火山喷发，引起了人们对冰岛S地质独特性和潜在的全球影响的关注。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能资源都与产生丰富的硅质熔岩、火山灰和花岗岩的不同寻常的海洋岩浆系统有关。该项目强调将矿物锆石作为示踪剂，以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，并为其动态的火山和地热系统提供动力。冰岛？S的大小和地壳的厚度，以及丰富的硅质岩浆作用，使其在地球上的S海洋岛屿中独一无二。这些特征导致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范例，可能模仿了40亿多年前第一块大陆的起源。值得注意的是，对冰岛地质的广泛研究缺乏对锆石的研究，而在其他地方，这些研究为我们了解岩浆作用和地球的起源和演化--S地壳--提供了许多基础。锆石是一种矿物，通常与大陆和岛弧的硅质岩有关，是对高温过程进行辐射测年的最持久和最可靠的材料，同时提供了有关其生长环境的信息。虽然冰岛-S地壳的大部分硅质(玄武岩)含量较低，因此锆石含量较低，但岛上较高硅质岩石(花岗岩和流纹岩)中含有足够的锆石来阐明其历史。这项调查建立在调查人员利用放射性测年和锆石的元素和同位素组成进行初步研究的基础上，以澄清冰岛硅质岩浆在喷发前产生、储存和修改的过程。这项研究将加深对冰岛岩浆和相关地热系统如何工作的理解。通过这样做，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(裂谷作用和羽流过程在硅质岩浆的产生中扮演了什么角色？冰岛是不是被大西洋打开时遗留下来的古代大陆地壳的碎片所覆盖？)

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?).