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Interaction of mantle dregs with convection: Lateral heterogeneity at the core‐mantle boundary
Author(s) -
Davies Geoffrey F.,
Gurnis Michael
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i013p01517
Subject(s) - mantle (geology) , geology , core–mantle boundary , mantle convection , geophysics , convection , mantle wedge , hotspot (geology) , amplitude , mechanics , subduction , seismology , tectonics , physics , quantum mechanics
Preliminary numerical models indicate that chemically denser material (dregs) at the base of the mantle would have substantial lateral variations in thickness induced by convection of the overlying mantle, and might well form discontinuous aggregations below mantle upwellings. A model with a density contrast of about 2 per cent and an initial uniform thickness of the denser layer of 100 km yields a discontinuous distribution with maximum thickness 230 km and bottom topography of several kilometers amplitude, in reasonable accord with recent seismological observations of vertical and lateral structure. Heat flux out of the core is probably strongly modulated laterally by mantle convection, while mantle dregs will complicate and possibly amplify this effect. Such modulation may be relevant to long‐term (10 7 ‐ 10 8 year) variations in the magnetic field.