Lead isotope evidence for young trace element enrichment in the oceanic upper mantle

Article Abstract:

The isotopic composition of lavas from several central Atlantic islands are probably associated with the uranium/lead (U/Pb) fractionation that took place while the local oceanic lithosphere was being formed. Analysis of neodymium, strontium and lead isotope levels from Madeira, Trinidade and elsewhere suggest also that the U/Pb fractionation probably happened at shallow depths of the mantle adjacent to the spreading mid-ocean ridge. These regions of influx from the mantle have been highly stable.

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Thallium isotopic evidence for ferromanganese sediments in the mantle source of Hawaiian basalts

Article Abstract:

Hawaiian picrites with osmium isotope anomalies exhibit pronounced thallium isotope variations and caesium/thallium ratios with values far lower than commonly observed for mantle-derived rocks. A sedimentary origin for the osmium isotope anomalies is inferred and implies a core-mantle interaction as a feasible explanation for the osmium isotope variations of the Hawaiian picrites.

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Inside the cosmic blender

Article Abstract:

The geochemists discuss the Solar System's isotopic composition which has tantalizing small variations. They are investigating the mechanisms and types of the stars producing these variations.

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