High-3He plume origin and temporal-spatial evolution of the Siberian flood basalts
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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 40Ar/39Ar 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-chondritic, 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.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | High-3He plume origin and temporal-spatial evolution of the Siberian flood basalts |
| Series title | Science |
| DOI | 10.1126/science.269.5225.822 |
| Volume | 269 |
| Issue | 5225 |
| Year Published | 1995 |
| Language | English |
| Publisher | American Association for the Advancement of Science |
| Description | 4 p. |
| First page | 822 |
| Last page | 825 |