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High-3He plume origin and temporal-spatial evolution of the Siberian flood basalts

Science
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Abstract

An olivine nephelinite from the lower part of a thick alkalic ultrabasic and mafic sequence of volcanic rocks of the northeastern part of the Siberian flood basalt province (SFBP) yielded a 40ArX39Ar plateau age of 253.3 ?? 2.6 million years, distinctly older than the main tholeiitic pulse of the SFBP at 250.0 million years. Olivine phenocrysts of this rock showed 3He/4He ratios up to 12.7 times the atmospheric ratio; these values suggest a lower mantle plume origin. The neodymium and strontium isotopes, rare earth element concentration patterns, and cerium/lead ratios of the associated rocks were also consistent with their derivation from a near-cnondritic, primitive plume. Geochemical data from the 250-million-year-old volcanic rocks higher up in the sequence indicate interaction of this high-3He SFBP plume with a suboceanic-type upper mantle beneath Siberia.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title High-3He plume origin and temporal-spatial evolution of the Siberian flood basalts
Series title Science
Volume 269
Issue 5225
Year Published 1995
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Science
First page 822
Last page 825
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