Two deep-mantle sources for Paleocene doming and volcanism in the North Atlantic.

The North Atlantic Igneous Province (NAIP) erupted in two major pulses that coincide with the continental breakup and the opening of the North Atlantic Ocean over a period from 62 to 54 Ma. The unknown mantle structure under the North Atlantic during the Paleocene represents a major missing link in deciphering the geodynamic causes of this event. To address this outstanding challenge, we use a back-and-forth iterative method for time-reversed global convection modeling over the Cenozoic Era which incorporates models of present-day tomography-based mantle heterogeneity.

On the deep-mantle origin of the Deccan Traps.

The Deccan Traps in west-central India constitute one of Earth's largest continental flood basalt provinces, whose eruption played a role in the Cretaceous-Paleogene extinction event. The unknown mantle structure under the Indian Ocean at the start of the Cenozoic presents a challenge for connecting the event to a deep mantle origin. We used a back-and-forth iterative method for time-reversed convection modeling, which incorporates tomography-based, present-day mantle heterogeneity to reconstruct mantle structure at the start of the Cenozoic.

Kinematics and dynamics of the East Pacific Rise linked to a stable, deep-mantle upwelling.

Earth's tectonic plates are generally considered to be driven largely by negative buoyancy associated with subduction of oceanic lithosphere. In this context, mid-ocean ridges (MORs) are passive plate boundaries whose divergence accommodates flow driven by subduction of oceanic slabs at trenches. We show that over the past 80 million years (My), the East Pacific Rise (EPR), Earth's dominant MOR, has been characterized by limited ridge-perpendicular migration and persistent, asymmetric ridge accretion that are anomalous relative to other MORs.

Dynamic topography change of the eastern United States since 3 million years ago.

Sedimentary rocks from Virginia through Florida record marine flooding during the mid-Pliocene. Several wave-cut scarps that at the time of deposition would have been horizontal are now draped over a warped surface with a maximum variation of 60 meters. We modeled dynamic topography by using mantle convection simulations that predict the amplitude and broad spatial distribution of this distortion.

Geodynamic and seismic constraints on the thermochemical structure and dynamics of convection in the deep mantle.

We revisit a recent study by Forte & Mitrovica in which global geophysical observables associated with mantle convection were inverted and the existence of a strong increase in viscosity near a depth of 2000 km was inferred. Employing mineral-physics data and theory we also showed that, although there are chemical anomalies in the lowermost mantle, they are unable to inhibit the dominant thermal buoyancy of the deep-mantle mega-plumes below Africa and the Pacific Ocean. New Monte Carlo simulations are employed to explore the impact of uncertainties in current mineral-physics constraints on inferences of deep-mantle thermochemical structure.