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Fuzzy patches on the Earth's core‐mantle boundary?
Author(s) -
Garnero Edward J.,
Jeanloz Raymond
Publication year - 2000
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 - 10.1029/2000gl008498
Subject(s) - mantle (geology) , core–mantle boundary , geology , geophysics , outer core , inner core , hotspot (geology)
Recent seismological investigations reveal the presence of highly anomalous structures at the base of the mantle, modeled as patches ≤5–50 km thick having ultralow‐velocities (−δV P ∼10–20%, −δV S ∼10–50%). Waveform modeling shows seismological data are compatible with the patches exhibiting a wide range of density increases, up to δρ∼60%, which can be ascribed to chemical contamination of the deep mantle by the core. Not all anomalies require lowermost mantle partial melting, and may be located just below or right at the core‐mantle boundary (CMB): a ∼1–3 km thick zone of finite rigidity (crystallization?) at the top of the outer core or, more generally, of gradational properties across the CMB can also explain observations. Fuzzy patches at the boundary may be zones of intense chemical and physical interactions between the mantle and core.