HIGH-HE-3 PLUME ORIGIN AND TEMPORAL-SPATIAL EVOLUTION OF THE SIBERIAN FLOOD BASALTS

被引:162
作者
BASU, AR
POREDA, RJ
RENNE, PR
TEICHMANN, F
VASILIEV, YR
SOBOLEV, NV
TURRIN, BD
机构
[1] BERKLEY GEOCHRONOL CTR, BERKELEY, CA 94709 USA
[2] RUSSIAN ACAD SCI, INST MINERAL & PETROL, NOVOSIBIRSK 630090, RUSSIA
[3] US GEOL SURVEY, MENLO PK, CA 94025 USA
关键词
D O I
10.1126/science.269.5225.822
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
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 He-3/He-4 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-He-3 SFBP plume with a suboceanic-type upper mantle beneath Siberia.
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页码:822 / 825
页数:4
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