SEMINAR - Jasper Konter

The Origin and Geologic Evolution of Seamounts in the Pacific Ocean

Jasper Konter
Department of Geological Sciences
San Diego State University

Wednesday, November 7th, 1:00pm GMCS 422

The “hotspot” hypothesis predicts that time-progressive linear chains of oceanic intraplate volcanoes (OIV) are formed on tectonic plates that pass over buoyantly rising plumes from fixed deep mantle sources. However, this hypothesis has been called into question by an alternate mechanism, which explains OIV chains by lithospheric extension and mantle melts rising to the surface along lithospheric fractures. Distinguishing between these models is very important because they imply a profoundly different dynamic and chemical state of the mantle that is likely to substantially influence the chemical evolution of the Earth. I will present new geochemical data from a geochemical study of several seamount chains in the Western Pacific, all likely erupted over the seismically anomalous Pacific mantle. These data provide a >100 myr geochemical record that can be related to three geochemically distinct active OIVs in the Cook-Austral region with the help of plate motion models. In a geophysical and geodynamic context these volcanoes should most likely be viewed as the result of deep mantle plumes, while lithospheric cracks are probably a secondary factor.