Mantle Plumes and Entrainment: Isotopic Evidence
- 24 April 1992
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 256 (5056) , 517-520
- https://doi.org/10.1126/science.256.5056.517
Abstract
Many oceanic island basalts show sublinear subparallel arrays in Sr-Nd-Pb isotopic space. The depleted upper mantle is rarely a mixing end-member of these arrays, as would be expected if mantle plumes originated at a 670-kilometer boundary layer and entrained upper mantle during ascent. Instead, the arrays are fan-shaped and appear to converge on a volume in isotopic space characterized by low 87 Sr/ 86 Sr and high 143 Nd/ 144 Nd, 206 Pb/ 204 Pb, and 3 He/ 4 He ratios. This new isotopic component may be the lower mantle, entrained into plumes originating from the core-mantle boundary layer.Keywords
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