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The argon constraints on mantle structure
Author(s) -
Allègre Claude J.,
Hofmann Albrecht,
O'Nions Keith
Publication year - 1996
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 - 10.1029/96gl03373
Subject(s) - mantle (geology) , geology , solid earth , argon , isotope , structure of the earth , geophysics , physics , atomic physics , nuclear physics
The 40 Ar budget of the Earth offers a powerful and straightforward argument in favour of the existence of a layered structure to the mantle. Whereas K‐Ar‐isotope systematics have been included as part of various discussions of mantle structure previously a simple and straightforward argument is presented here. Because 40 Ar is produced by 40 K the amount of K in the Earth may be constrained from 40 Ar budgets. The atmospheric 40 Ar budget implies that approximately half of all 40 Ar produced within the Earth since its formation is retained within the solid Earth. It is argued that this additional 40 Ar is located principally in the lower mantle.