SO2 disproportionation impacting hydrothermal sulfur cycling: Insights from multiple sulfur isotopes for hydrothermal fluids from the Tonga-Kermadec intraoceanic arc and the NE Lau Basin

Peters C, Strauss H, Haase K, Bach W, De Ronde C, Kleint C, Stucker V, Diehl A (2021)

Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2021

Journal

Chemical Geology Elsevier

Book Volume: 586

Article Number: 120586

DOI: 10.1016/j.chemgeo.2021.120586

Abstract

Hydrothermal systems located at intra-oceanic volcanic arcs and in back-arc basins reveal a complex sulfur cycling. Here we present multiple sulfur isotope data for dissolved sulfide and sulfate in hydrothermal fluids from vent sites at the southern Kermadec and the northern Tonga island arcs and the NE Lau Basin. δ34S values for H2S range from −7.4 to +4.6‰ for hydrothermal fluids from arc volcanoes and from +0.2 to +4.5‰ for those located in the NE Lau Basin. Ranges for Δ33S values are −0.010 to +0.033‰ and −0.016 to +0.011‰, respectively. SO42− in fluids from hydrothermal vents at Macauley caldera, the Brothers volcanic cones, and Niua North show ranges in δ34S and Δ33S from +16.7 to +24.7‰ and +0.013 to +0.049‰. The multiple sulfur isotope data suggest a contribution to the hydrothermal sulfur budget from the disproportionation of magmatic SO2 for most hydrothermal vent sites from the Kermadec arc, whereas H2S at the NE Lau Basin vent sites is thought to result mainly from two-component mixing between host rock-derived sulfur and seawater sulfate with an additional local contribution from SO2 disproportionation. Data from Brothers NW Caldera suggest isotope exchange between H2S and SO42−, whereas lowering of fluid acidity by dissolution of mineral phases occurs at the Brothers Lower Cone. δ34S values between −8.5 and +3.1‰ and Δ33S values between +0.009 and +0.036‰ for elemental sulfur indicate changing redox conditions and/or a decrease of magmatic SO2 in the hydrothermal fluids at Macauley, Haungaroa, Brothers Lower Cone, Niua North and Niuatahi. We conclude that acid sulfate venting in particular shows the highest variability in sulfur isotopic composition of hydrothermal sulfur, irrespective of whether located at an intra-oceanic arc or in a back-arc basin. Sulfur isotope heterogeneity is due to variable contributions from SO2 disproportionation and host rock compositions.

Authors with CRIS profile

Karsten Haase Lehrstuhl für Endogene Geodynamik

Related research project(s)

Magmatic evolution of island arc and backarc crust and implications for hydrothermal venting in the NE Tonga arc (TONGARIFT) TONGARIFT Feb. 1, 2018 - March 31, 2020

Involved external institutions

Universität Bremen DE Germany (DE) Westfälische Wilhelms-Universität (WWU) Münster DE Germany (DE)

How to cite

APA:

Peters, C., Strauss, H., Haase, K., Bach, W., De Ronde, C., Kleint, C.,... Diehl, A. (2021). SO2 disproportionation impacting hydrothermal sulfur cycling: Insights from multiple sulfur isotopes for hydrothermal fluids from the Tonga-Kermadec intraoceanic arc and the NE Lau Basin. Chemical Geology, 586. https://dx.doi.org/10.1016/j.chemgeo.2021.120586

MLA:

Peters, Christian, et al. "SO2 disproportionation impacting hydrothermal sulfur cycling: Insights from multiple sulfur isotopes for hydrothermal fluids from the Tonga-Kermadec intraoceanic arc and the NE Lau Basin." Chemical Geology 586 (2021).

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