Strong heterogeneity caused by deep mantle layering

Strong, Multi-Scale Heterogeneity in Earth's Lowermost Mantle.

The core mantle boundary (CMB) separates Earth's liquid iron outer core from the solid but slowly convecting mantle. The detailed structure and dynamics of the mantle within ~300 km of this interface remain enigmatic: it is a complex region, which exhibits thermal, compositional and phase-related heterogeneity, isolated pockets of partial melt and strong variations in seismic velocity and aniso...

Mantle layering across central South America

[1] Imaging of seismic velocity discontinuities along a 3000 km profile across central South America at 20 S suggests that the depth variations of the 410-km (d410) and 660-km (d660) discontinuities are closely associated with the high-velocity Nazca slab and juxtaposed low-velocity oceanic mantle beneath the slab. The mantle transition zone thickness ranges from 220 km in the oceanic mantle to...

Layering of a Thermochemical Plume in the Upper Mantle Beneath

Inefficiency caused by random matching and heterogeneity

I study an economy with sellers and buyers with unit supplies and unit demands. Both parties have valuations uniformly distributed on a unit interval. I quantify the inefficiency, compared to the Walrasian market, caused by a market where the agents meet randomly. There are several causes of inefficiency that I deal with separately. First, even if there is perfect information about valuations i...

Compositional mantle layering revealed by slab stagnation at ~1000-km depth.

Improved constraints on lower-mantle composition are fundamental to understand the accretion, differentiation, and thermochemical evolution of our planet. Cosmochemical arguments indicate that lower-mantle rocks may be enriched in Si relative to upper-mantle pyrolite, whereas seismic tomography images suggest whole-mantle convection and hence appear to imply efficient mantle mixing. This study ...