13 June, 2008 (16:00 GMT), 5 Merrion Square, Dublin 2.

Speaker: John O’Conner (VU University Amsterdam)
Title: Testing a new hotspot-plume model for the Hawaiian-Emperor Chain.

Abstract:

Although fixed hotspots and mantle plumes have been fundamental hypotheses in marine geosciences for more than 30 years, both are now being widely disputed. Whether or not mantle plumes form hotspots and their associated volcanic trails, the fixity of such mantle upwellings, and the depth(s) and composition(s) of their sources are of pivotal importance for geodynamic models of the mantle and the motions of tectonic plates. Volcanic propagation along seamount chains, most notably the archetypal Hawaiian-Emperor Chain with its Great Bend, is the key observation underpinning the notion that tectonic plates drift over fixed hotspots/plumes. But, we are proposing a different model for the Hawaiian-Emperor Chain on the basis of isotopic ages for new volcano samples and information about mantle flow inferred from diverse geophysical sources. I will talk about our new model for the Hawaiian-Emperor Chain and projects planned for testing its validity on a significantly more global scale. Understanding what these new data might mean will continue to depend critically on inferring fundamental information about the mantle from tomography, numerical modeling, plate reconstructions and possibly also the timing of major global environmental and biotic changes.