Isotopic evolution of Mauna Loa and the chemical structure of the Hawaiian plume

[1] Abstract: New He isotopic data from the HSDP pilot hole core, lava accumulation rate models, and data from the literature are used to develop a 200,000 year isotopic record for the lava erupted from the Mauna Loa volcano. This record, coupled with an analogous record from Mauna Kea from the Hawaii Scientific Drilling Project (HSDP) pilot hole project and other literature data from the GEOROC database, are used to construct a ‘‘map’ ’ of lava isotopic compositions for the island of Hawaii. The isotopic map is converted to a map of the He and Nd isotopic compositions of melts from the mantle plume, which can be compared with a published melt supply map derived from geodynamic modeling. The resulting map of the plume indicates that values of helium 3He/4He> 20 Ra are confined to the core of the plume (radius 20–25 km) and correspond to potential temperatures>15658C, suggesting the He isotopic signal is derived from deep in the mantle. The 3He/4He map has close