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Metal isotope signatures from lava-seawater interaction during the 2018 eruption of Kīlauea

Lookup NU author(s): Professor Sam Wilson

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© 2020 The AuthorsThe 2018 eruption of Kīlauea was associated with massive input of molten lava into the coastal ocean, which altered seawater chemistry and increased phytoplankton production. In seawater plumes advected away from the site of lava entry, we observed elevated concentrations of over a dozen metals relative to background seawater and unique isotopic compositions of Fe, Cu, Ni, Cd and Zn. The δ56Fe of iron released from lava was lower than basaltic, riverine and coastal iron from Hawaiʻi, but similar to observations of other high-temperature hydrothermal vent fluids. However, rapid precipitation led to only modest enrichments in dissolved iron (<10 nM), with increasing dissolved δ56Fe likely due to fractionation associated with ligand-mediated dissolution of particulate Fe. The isotopic composition of copper and nickel show evidence for two-endmember mixing between background seawater and a lava source. While the Ni isotopic endmember reflected basaltic δ60Ni, endmember δ65Cu, δ66Zn, and δ114Cd were isotopically lighter than basalt. We hypothesize that high diffusivity and volatility of chalcophile elements leads to strong kinetic fractionation in rapidly cooling lavas, similar to Cu, Zn and Cd isotopic patterns observed in tektites. The isotopic signatures of Cu and Ni observed during the 2018 eruption of Kīlauea far exceed their normal seawater range and may be useful for identifying large-scale lava input into ocean waters during the formation of large igneous provinces and other episodes of volcanism.


Publication metadata

Author(s): Hawco NJ, Yang S-C, Foreman RK, Funkey CP, Dugenne M, White AE, Wilson ST, Kelly RL, Bian X, Huang K-F, Karl DM, John SG

Publication type: Article

Publication status: Published

Journal: Geochimica et Cosmochimica Acta

Year: 2020

Volume: 282

Pages: 340-356

Print publication date: 01/08/2020

Online publication date: 28/05/2020

Acceptance date: 04/05/2020

Date deposited: 16/12/2021

ISSN (print): 0016-7037

ISSN (electronic): 1872-9533

Publisher: Elsevier Ltd

URL: https://doi.org/10.1016/j.gca.2020.05.005

DOI: 10.1016/j.gca.2020.05.005


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