Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9529130 | Chemical Geology | 2005 | 14 Pages |
Abstract
Low 40Ar/36Ar ratios occur only in samples with low δ18O, consistent with a near-surface origin (i.e., alteration or assimilation of altered volcanics) of both the low δ18O and low 40Ar/36Ar in most samples. However, high 40Ar/36Ar ratios (up to 6500) measured in some samples-the samples that have the highest δ18O-is consistent with little or no alteration of these samples. These high 40Ar/36Ar samples have δ18O ±4.6â°, significantly lower than that of the MORB source region (5.2â°). It seems likely that, while alteration by meteoric fluids does influence oxygen isotopic composition, δ18O of the mantle source to these basalts is ±4.6â°. Low δ18O in the Icelandic mantle source could be the result of recycling lithospheric mantle, although this is not likely the source of high 3He/4He ratios in Iceland.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Pete Burnard, Darrell Harrison,