Helmholtz Centre Potsdam
GFZ German Research Centre for Geosciences
Abstract (EDOC: 13978)
The debate concerning thermal plumes in the Earth's mantle, their geophysical detection and depth characterization remains contentious. Available geophysical, petrological and geochemical evidence is at variance regarding the very existence of mantle plumes. Utilizing P-to-S converted seismic waves (P receiver functions= from the 410 and 660 km discontinuities, we investigate disposition of these boundaries beneath a number of prominent hotspot regions. The thickness of the mantle transition zone (MTZ), measured as P660s-P410sdifferential times (tMTZ), is determined. Our analyses suggest that the MTZ thickness beneath some hotspots correlates with the plume strength. The relationship between TMTZ, in response to the thermal perturbation, and the strength of plumes, as buoyancy flux B, follows a power law excess temperature at 410 – 669 km depth below hotspots. We find that the strongest hotspots, which are located in the Pacific, are indeed plumes originating at the MTZ or deeper. According to the detected power law, even the strongest plumes may not shrink the transition zone by significantly more than ~ 40 km (corresponding to a maximum of 300-400° excess temperature).
(2010): Response of mantle transition zone thickness to plume buoyancy flux. Geophysical Journal International, 180, 1, 49-58.