Current Research

Plume-Ridge Interaction Plume-ridge interaction involves the combined effects of a self-spreading, buoyant mantle-plume and a nearby divergent plate boundary (i.e. mid-ocean ridge). Through examination of the depth-integrated stresses due to this interaction, we can calculate the stress field in the lithosphere as a fraction of the lithospheric yield strength (at right). The pattern is sensitive to the plume-ridge separation distance and the size of the transform fault as well as the far field and local boundary conditions. Formation of Volcanic Lineaments The process of diking and volcano loading decreases the integrated tension in the underlying lithosphere and leads to tensile stress concentrations near the ends of a lineament. This will promote new volcanism and lengthening of the lineament in a manner much like a giant crack in the lithosphere. Volcanism initiates where magma supply is high and tension is a large fraction of the lithospheric yield strength near the ridge axis. Volcanism subsequently propagates away from the ridge roughly according to the preexisting lithospheric stress field. Plume Heat Flux Recently published in Earth and Planetary Science Letters and featured in Nature (Mittelstaedt and Tackley, 2006), we perform a study on the heat flux carried by mantle plumes from the core-mantle boundary to the base of the lithosphere. We find that the heat flux carried by plumes is much less than the heat flux out of the CMB.

The above bathymetry map (top) shows the series of lineaments found between the Galapagos Archipelago and the Galapagos Spreading Center. The lower image is the result of modeling the stresses introduced in the lithosphere by a spreading mantle plume near a mid-ocean ridge. The tic marks are lines of least depth-integrated tension and predict possible trajectories of lineament formation. Image after Mittelstaedt and Ito (2005)