Osmium and neodymium isotopic constraints on the temporal and spatial evolution of Siberian flood basalt sources

Geochimica et Cosmochimica Acta
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Abstract

Picrites from the Gudchikhinsky suite, the oldest rocks examined, have ??Os of +5.3 to +6.1 and ??Nd of +3.7 to +4.0. The osmium and neodymium isotopic compositions of these rocks are similar to some modern ocean-island basalts (OIB), consistent with their derivation from an mantle plume. Picrites from the stratigraphically higher Tuklonsky suite have similar ??Os of +3.4 to +6.5, but ??Nd of -0.9 to -2.6. The similar ??Os, but lower ??Nd , suggest that some magmas from the same OIB-type, mantle source were contaminated by lithospheric components. A differentiated ankaramite flow, associated with the top of the stratigraphically higher Morongovsky suite, has ??Os of +9.8 to +10.2 and ??Nd of +1.3 to +1.4. The higher ??Os may indicate that the plume source was heterogeneous with respect to osmium isotopic composition, consistent with osmium isotopic measurements in rocks from other plume sources. Mg-rich, alkaline rocks (meymechites) from the Guli area that erupted much nearer the end of the flood-basalt event have ??Os of -1.2 to -2.6 and ??Nd of +3.7 to +4.9. These rocks were probably produced by low degrees of partial melting of mantle after the main stages of flood-basalt production. -from Authors

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Osmium and neodymium isotopic constraints on the temporal and spatial evolution of Siberian flood basalt sources
Series title Geochimica et Cosmochimica Acta
DOI 10.1016/0016-7037(96)89674-8
Volume 59
Issue 24
Year Published 1995
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Geochimica et Cosmochimica Acta
First page 5159
Last page 5168
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