Two magma bodies beneath the summit of Kilauea Volcano unveiled by isotopically distinct melt deliveries from the mantle

Aaron J. Pietruszka; Daniel E. Heaton; Jared P. Marske; Michael O. Garcia

doi:10.1016/j.epsl.2014.12.040

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Two magma bodies beneath the summit of Kilauea Volcano unveiled by isotopically distinct melt deliveries from the mantle

Aaron J. Pietruszka·Daniel E. Heaton·Jared P. Marske·Michael O. Garcia

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Abstract

The summit magma storage reservoir of Kīlauea Volcano is one of the most important components of the magmatic plumbing system of this frequently active basaltic shield-building volcano. Here we use new high-precision Pb isotopic analyses of Kīlauea summit lavas—from 1959 to the active Halema‘uma‘u lava lake—to infer the number, size, and interconnectedness of magma bodies within the volcano's summit reservoir. From 1971 to 1982, the 206 Pb/ 204 Pb ratios of the lavas define two separate magma mixing trends that correlate with differences in vent location and/or pre-eruptive magma temperature. These relationships, which contrast with a single magma mixing trend for lavas from 1959 to 1968, indicate that Kīlauea summit eruptions since at least 1971 were supplied from two distinct magma bodies. The locations of these magma bodies are inferred to coincide with two major deformation centers identified by geodetic monitoring of the volcano's summit region: (1) the main locus of the summit reservoir &sim;2–4 km below the southern rim of Kīlauea Caldera and (2) a shallower magma body <2 km below the eastern rim of Halema‘uma‘u pit crater. Residence time modeling suggests that the total volume of magma within Kīlauea's summit reservoir during the late 20th century (1959–1982) was exceedingly small (&sim;0.1–0.5 km 3 ). Voluminous Kīlauea eruptions, such as the ongoing, 32-yr old Pu‘u ‘Ō‘ō rift eruption (>4 km 3 of lava erupted), must therefore be sustained by a nearly continuous supply of new melt from the mantle. The model results show that a minimum of four compositionally distinct, mantle-derived magma batches were delivered to the volcano (at least three directly to the summit reservoir) since 1959. These melt inputs correlate with the initiation of energetic (1959 Kīlauea Iki) and/or sustained (1969–1974 Mauna Ulu, 1983-present Pu‘u ‘Ō‘ō and 2008-present Halema‘uma‘u) eruptions. Thus, Kīlauea's eruptive behavior is partly tied to the delivery of new magma batches from the volcano's source region within the Hawaiian mantle plume.

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Earth and Planetary Science Letters Article

Source-reported bounding extent: 19.344188652729514° to 19.38451428768728° latitude; -155.20042419433594° to -155.12231826782227° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Aaron J. Pietruszka, Daniel E. Heaton, Jared P. Marske, Michael O. Garcia. 2015. Two magma bodies beneath the summit of Kilauea Volcano unveiled by isotopically distinct melt deliveries from the mantle. https://doi.org/10.1016/j.epsl.2014.12.040

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