127-9 Isotope and Geochemical Characteristics of Lavas from GVP 243030 of the Tonga Arc in the Context of Hunga Tonga.

Session: Mineralogy, Geochemistry, Petrology, and Volcanology Student Session

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Abstract:

The Tonga Arc seamount designated GVP 243030, located 33 kilometers northwest of the main island of Tongatapu (Kingdom of Tonga), has not been studied despite recorded eruptions in 1911, 1923, 1999, and 2017 and proximity to populated areas (Global Volcanism Project, 2017). The nearby volcano Hunga Tonga-Hunga Ha’apai, erupted in 1912, 1937, 1988, 2009, and 2015, with the most recent being the 2022 VEI 6 eruption, which resulted in destructive tsunamis, ashfalls, and measurable impacts on global climate through stratospheric sulfur and water injection (Le Mevel et al., 2023; Walker and de Ronde, 2024). The GVP 243030 seamount likely poses similar hazards that necessitate characterizing its geochemical composition to place it in context with other volcanoes in the arc and determine whether the seamount is capable of eruptions similar in scale to Hunga Tonga.

We present petrological and geochemical evaluations of two volcanic rocks dredged from the GVP 243030 seamount in the context of erupted material from Hunga Tonga. Samples were crushed and picked for crystal-free groundmass and then analyzed for major and trace element concentrations as well as isotope ratio analyses of rubidium-strontium, uranium-thorium, radium-thorium, and calcium-barium isotopes. Lava bombs from the GVP 243030 seamount contain higher abundances of forsterite and pyroxene in contrast to Hunga Tonga eruptives, potentially indicating different petrogenetic and magma staging histories.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9573

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