70 Ma chemical zonation of the Tristan-Gough hotspot track
Joana Rohde et al., GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1-3, 24148 Kiel, Germany. Posted online 25 Jan. 2013; http://dx.doi.org/10.1130/G33790.1.
Hotspot tracks are age-progressive chains of volcanoes that form as lithosphere moves over a mantle plume. Some Pacific hotspot tracks display a spatial geochemical zonation with distinct isotopic domains attributed to their location above the margin of the Pacific superplume, a large-scale low-shear velocity province in the lower mantle beneath the southern Pacific. Joana Rohde and colleagues investigate geochemical variations along the Tristan-Gough hotspot track in the South Atlantic to evaluate if such spatial compositional heterogeneities also exist in the Atlantic. They observe that the isotopic compositions display a bilateral zonation with two distinct mantle source compositions, making Tristan-Gough the first chemically zoned plume to be recognized overlying the African superplume. Moreover, the zonation is traced for at least 70 million years, four times
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