Evidence for two shield volcanoes exposed on the island of Kauai, Hawaii

The island of Kauai has always been interpreted as a single shield volcano, but lavas of previously correlated reversed-to-normal magnetic-polarity transitions on opposite sides of the island differ significantly in isotopic composition. Samples from west Kauai have ⁸⁷Sr/⁸⁶Sr < 0.7037, ϵ_Nd ≥ 6.14, and ²⁰⁶Pb/²⁰⁴Pb > 18.25; samples from east Kauai have ⁸⁷Sr/⁸⁶Sr > 0.7037, ϵ_Nd ≤ 6.14, and ²⁰⁶Pb/²⁰⁴Pb < 18.25. Available data suggest that a younger eastern shield grew on the collapsed flank of an older western one.