Rust marks second-hand crust

Article Abstract:

The major-element chemistry of the Hawaiian mantle plume is significantly different from that of the upper-mantle source of mid-ocean-ridge basalts. Radiogenic isotope surveys attribute the differences to the presence of higher levels of iron oxide in the Hawaiian plume due to recycling of ocean crust. The results are significant for seismologists and geodynamicists as iron concentration significantly influences the physical properties of rocks, such as density and seismic velocity. The major-element composition serves as a testing ground for theories related to the origin of mantle plumes.

Usage, Observations, Earth, Radiochemical analysis, Ferric oxide, Mantle (Geology)

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Isotopic evidence for Late Cretaceous plume-ridge interaction at the Hawaiian hotspot

Article Abstract:

Sr-Nd-Pb isotopic analyses of samples from the next-to-oldest seamount in the Hawaiian hotspot track, the Detroit seamount at 51 degrees N, are presented. There is evidence that, 81 Myr ago, the Hawaiian hotspot produced volcanism with an isotopic signature exactly the same as mid-ocean ridge basalt.

Geology, Stratigraphic, Stratigraphy, Seamounts, Cretaceous period

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Helium not in store

Article Abstract:

The ratio of helium isotopes in some oceanic volcanoes seemed to demand a reservoir of virgin primordial gas in the Earth's mantle. They require layered convection that seismologists cannot detect and geodynamics cannot reproduce in their models and need a primordial deep mantle.

United States, Science & research, Volcanological research, Helium, Helium isotopes, Mantle convection

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