The Emperor‐Hawaiian Chain Magmatism: 80 Ma of Isothermal Melting

Abstract The Emperor–Hawaiian volcanic chain, which extends across the Pacific Plate, is a classic example of a structure formed through the interaction between a long‐lived mantle melting anomaly and the moving oceanic lithosphere. Olivine‐rich rocks sampled along the chain were examined using Cr‐spinel and melt inclusions hosted in the most primitive olivine phenocrysts to constrain the characteristics of the mantle source and its melting conditions. The studied samples represent the Detroit (76–81 Ma), Suiko (61 Ma) and Koko (48–49 Ma) seamounts, as well as sand from Papakōlea Beach (<150 Ka Puʻu Mahana tuff ring related to Mauna Loa volcano) on Hawai'i Island. Thermometric data derived from olivine–spinel and olivine–melt pairs indicate that there is no significant temperature difference between old Emperor seamounts and modern Hawai'i, whereas trace‐element compositions of liquidus olivine and reconstructed melts suggest a progressive increase in melting depth. Mantle potential temperature of modern Hawai'i is estimated as ∼1,490 ± 84°C, which is in agreement with previous geophysical modeling.