Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: AGU Advances
The most isotopically-enriched Hawaiian magmas are sourced in the most depleted peridotites which result in a larger melt productivity per unit time. Although this is counterintuitive to many, it is the buoyancy that determines the upwelling rate of the plume and thus the processing rate of the mantle. The isotopic composition of the Hawaiian magmas show that the plume consists mostly out of peridotite that have undergone various degrees of depletion due to earlier melting near the Earth’s surface. Magmatic flux of the Hawaiian plume increases with increasing degree of depletion of peridotite. This increased depletion results in a blank “canvas” for heterogeneities to biases the melts to more enriched isotopic compositions.
The eruption volume and rate of the Hawaiian hot spot has seen significant variations over the last 47 million years. Béguelin et al. [2025] use a minimum set of assumptions and a wide range of compositional space for a peridotitic mantle and recycled oceanic crust (igneous and sedimentary) to calculate, by Monto Carlo simulations, the relative abundance of each component in the Hawaiian plume. More enriched isotopic composition and increased magma production is explained by increased plume flux due to higher buoyancy related to prior melt depletion of the predominant peridotite component. The isotope signatures are becoming more enriched as the signal of the more depleted peridotite is overwhelmed by the recycled component.
The dominant peridotitic component of the plume determines its density and buoyancy with the more melt-depleted peridotite being less dense and more buoyant. If the plume shifts to a more melt-depleted peridotite, its melt production per unit, time increases due to the higher upwelling rate while the isotopic composition in the magmas shifts to compositions of the enriched components. This model explains the increase in magma volume over the last 3 million years compared to the earlier history Hawaiian magmatism and the waxing and waning of magmatic activity.
Citation: Béguelin, P., Stracke, A., Ballmer, M. D., Huang, S., Willig, M., & Bizimis, M. (2025). Variations in Hawaiian plume flux controlled by ancient mantle depletion. AGU Advances, 6, e2024AV001434. https://doi.org/10.1029/2024AV001434
—Vincent Salters, Editor, AGU Advances