Open AccessResponse of mantle transition zone thickness to plume buoyancy flux
Author(s) -
Das Sharma S.,
Ramesh D. S.,
Li X.,
Yuan X.,
Sreenivas B.,
Kind R.
Publication year - 2010
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2009.04403.x
Subject(s) - transition zone , geology , buoyancy , hotspot (geology) , plume , geophysics , mantle plume , classification of discontinuities , mantle (geology) , seismology , mechanics , tectonics , meteorology , lithosphere , physics , mathematical analysis , mathematics
SUMMARY 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 − P410s differential times ( t MTZ ), is determined. Our analyses suggest that the MTZ thickness beneath some hotspots correlates with the plume strength. The relationship between t MTZ , in response to the thermal perturbation, and the strength of plumes, as buoyancy flux B , follows a power law. This B–t MTZ behavior provides unprecedented insights into the relation of buoyancy flux and excess temperature at 410–660 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).