Collaborative Research: Insights into plume-lithosphere interactions from Hawaiian mantle xenoliths

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This study will involve petrographic work, mineral chemical analysis (major and trace elements), and Hf, Os, Sr, Pb, and Nd isotope study of mineral separates from spinel peridotite and garnet "pyroxenite suite" xenoliths from the post-erosional Honolulu Volcanics (HV) of Oahu. The xenoliths come from three vents: Salt Lake crater (SLC) is located on the rim of the Koolau volcano; and Kaau and Pali vents are located close to its caldera. The first order goal under this award is to infer xenolith origins using the combined isotopic and mineral chemical information. The isotopic information and mineral thermobarometry on the xenoliths will allow the PIs to recognize the types of materials (subducted crust and mantle or even lower mantle or transition zone materials) that may have been brought up by the Hawaiian plume versus those that have a lithospheric origin. The study will offer a direct insight into the isotopic variability of the shallow mantle beneath Oahu irrespective of their origin in the plume, the lithosphere, or as a mixed product of plume, lithosphere or asthenosphere- derived components. Once these are identified, existing models on Hawaiian volcanism and lithospheric processes may be fine-tuned or better models may be proposed.