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?).
