Mantle Plumes and Entrainment: Isotopic Evidence
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 87Sr/86Sr and high 143Nd/144Nd, 206Pb/204Pb, and ^3He/^4He ratios. This new isotopic component may be the lower mantle, entrained into plumes originating from the core-mantle boundary layer.
- Publication:
-
Science
- Pub Date:
- April 1992
- DOI:
- 10.1126/science.256.5056.517
- Bibcode:
- 1992Sci...256..517H
- Keywords:
-
- Basalt;
- Earth Mantle;
- Entrainment;
- Isotopic Enrichment;
- Plumes;
- Geochronology;
- Ocean Bottom;
- Radioactive Age Determination;
- Volcanoes;
- Geophysics