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Trace element and isotopic effects arising from magma migration beneath mid-ocean ridgesThe trace element concentrations and isotopic ratios in the magma erupted on mid-ocean ridges may differ from those in the source material due to physical effects such as porous flow dispersion, exchange of trace elements between the fluid and solid phases during magma migration, and convective mixing in magma chambers. These differences are in addition to those produced by better known processes such as fractional crystallization and partial melting. The effects of the three former processes are described. It is predicted that magma typically reaches the subridge magma chambers with a spatial heterogeneity only slightly reduced from that of the source material, but with a subdued variation in time. Convective mixing then further reduces the spatial heterogeneity. Application of the results for convective mixing to a recent Fourier analysis of Sr-87/Sr-86 variations along the Mid-Atlantic Ridge suggests that the falloff in amplitude of variation observed with decreasing wavelength in the Mid-Atlantic Ridge data cannot be explained by convective mixing in magma chambers. Instead, it is postulated that this falloff is due to the mechanics of the production and/or the solid-state convective mixing of chemical and isotopic heterogeneities in the solid mantle.
Document ID
19910037076
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kenyon, Patricia M.
(Carnegie Institution of Washington Washington, DC, United States)
Date Acquired
August 15, 2013
Publication Date
December 1, 1990
Publication Information
Publication: Earth and Planetary Science Letters
Volume: 101
Issue: 4-Feb
ISSN: 0012-821X
Subject Category
Geophysics
Accession Number
91A21699
Funding Number(s)
CONTRACT_GRANT: NAGW-398
Distribution Limits
Public
Copyright
Other

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