Testing the Recycled Gabbro Hypothesis for the Origin of “Ghost Plagioclase” Melt Signatures Using ⁸⁷ Sr/ ⁸⁶ Sr of Individual Olivine‐Hosted Melt Inclusions From Hawai'i

Melt inclusions with large, positive Sr anomalies have been described in multiple tectonic settings, and the origins of this unusual geochemical feature are debated. Three proposed, all involving plagioclase as source elevated Sr: (i) direct assimilation plagioclase-rich lithologies, (ii) recycled lower oceanic gabbro mantle source, (iii) shallow-level diffusive interaction between present day crust (i.e., plagioclase-bearing lithologies) percolating melt. A “ghost plagioclase” signature a anomaly without associated high Al2O3) is melt from Mauna Loa. We new 87Sr/86Sr measurements individual olivine-hosted three Hawaiian volcanoes, Loa, Loihi, Koolau. The data set includes Loa inclusion highest reported (or (Sr/Ce)N, which 7.2) for Hawai'i. All values within range previously lavas each volcano. Critically, (Sr/Ce)N lies narrow melts that lack signatures. Therefore, to explain ratio ghost using an ancient gabbro, gabbro-infused would had evolve, by chance, same (ghost plagioclase) signature. Alternatively, interactions cumulates mantle-derived provides simpler explanation presence melts.