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Topography at the core‐mantle boundary
Author(s) -
Bowin Carl
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/gl013i013p01513
Subject(s) - geoid , geology , mantle (geology) , core–mantle boundary , geophysics , geodesy , density contrast , gravity anomaly , inner core , planet , anomaly (physics) , physics , paleontology , measured depth , condensed matter physics , astronomy , oil field , astrophysics
Analysis of the Earth's gravity field using ratio of gravity to geoid (g/N) and cumulative degree contribution curve techniques improves resolution of the mass, depth, and dimensions of anomalous mass sources within the planet. The source for four of the ten major geoid anomalies of the Earth has large contributions from harmonic degrees 2 and 3, lie at the core‐mantle boundary, and the greatest has a mass anomaly of 4.2·10 22 grams. That boundary has a density contrast (4.4 gm/cm³) which is greater than at any other location, including the contrast at the Earth's surface with space. Thus, relatively small vertical undulations of that boundary produce very large mass anomalies. Topographic relief of less than 3 km at the core‐mantle boundary occurs, and accounts for the existence of the largest geoid anomalies occurring on the Earth.