A young crustal component in the Caroline plume

The geochemical variability in oceanic island basalts is linked to Earth’s deep mantle heterogeneity, with distinct mantle components of which origin is under debate. In this study, we found basalts from the Caroline Seamount Chain exhibit an unusually high primitive δ57Fe signature. The association of high δ57Fe with mildly depleted Nd–Hf isotope compositions indicates the involvement of a young crustal component in the Caroline plume, which was introduced into the Pacific Large Low Shear Velocity Province (LLSVP) by the subduction girdle surrounded Rodinia supercontinent about 600 million years ago. Similar endmembers are also found in basalts from hotspots near the boundary of the Pacific LLSVP, including Hawaii and Galapagos, but not seen in basalts from hotspots centered in the Pacific LLSVP. We suggest the circum-Rodinia subduction could lead to such preferential appearance of young crustal materials, and consequently result in the zoned compositional structure of the Pacific LLSVP.