GEOL 5903 Seminar: Alicia Moning
31 March, 2017
GEOL 5903 Seminar: Alicia Moning
Title: "Mantle Plumes: Do they exist? Icelandic Volcanism as an example"
Location: Huggins Science Hall, Room 336, 12:30 p.m.
Abstract:
Iceland began to form approximately 60 million years ago, when the North American and Eurasian plates separated to form the North Atlantic Ocean. Iceland resulted from anomalously large amounts of upwelling of magma in one area along the constructive margin. Hence, although plate tectonics plays a role in the formation of Iceland, the large amounts of magma needed to form a land mass, and have continued upwelling, as seen in Iceland today, requires another component to the story. Mantle plumes were proposed 50 years ago to explain anomalously large areas of magmatic activity such as Iceland, but remain controversial. A mantle plume is a column of hot mantle rock rising toward the Earth’s surface, driven by heat. The upwelling of hot mantle produces a “hot spot” of volcanic activity on the Earth’s surface. Seismic tomography and whole-rock and isotopic geochemistry provide strong arguments for a mantle plume under Iceland; for example, the chemical characteristics of the least evolved lava of Iceland are different from N-MORB. However, crustal thickness as well as lack of evidence for temperature anomalies underneath Iceland are evidence that no mantle plume is present.