High-3He Plume Origin and Temporal-Spatial Evolution of the Siberian Flood Basalts

A. R. Basu, R. J. Poreda, P. R. Renne, F. Teichmann, Y. R. Vasiliev, N. V. Sobolev, B. D. Turrin
1995 Science  
0.0124 ±+ 0.003, using negative thermal ionization techniques and fractionation correcting to a 194Pt/ 95pt ratio of 0.9734 (38). 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
more » ... his 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
doi:10.1126/science.269.5225.822 pmid:17778742 fatcat:xmk5yoru2zh2tjtqth4tsvtrse