Spatial Variations in Magmatic Volatile Influx and Fluid Boiling in the Submarine Hydrothermal Systems of Niuatahi Caldera, Tonga Rear-Arc

Falkenberg J, Keith M, Haase K, Sporer C, Bach W, Klemd R, Strauss H, Storch B, Peters C, Rubin KH, Anderson MO (2022)


Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2022

Journal

Book Volume: 23

Journal Issue: 4

DOI: 10.1029/2021GC010259

Abstract

Submarine caldera volcanoes may host several hydrothermal systems along the caldera wall and related to volcanic cones. Fluid boiling and magmatic volatile influx are common processes in shallow (<2,000 mbsl) subduction zone-related environments causing variations in the mineralogical and chemical composition of seafloor hydrothermal mineralizations that remain poorly constrained. The submarine caldera of Niuatahi volcano, Tonga rear-arc, hosts four active vent sites discharging high temperature fluids (<334 degrees C) with variable salinities (369-583 mM Cl) that are indicative of fluid boiling, recorded by distinct Te/As and Te/Au in pyrite, sphalerite, and chalcopyrite. High sulfidation mineral assemblages (e.g., enargite), stable S isotope data and similar trace element signatures in sulfides and native S condensates suggest a minor and/or infrequent contribution of magmatic SO2 to the hydrothermal systems located proximal to the caldera center causing a volatile element (e.g., Se, Bi, Te) enrichment. The hydrothermal system at the northern caldera wall is decoupled from the magmatic SO2 source, as revealed by radiogenic Pb isotopes. Instead, S isotope and trace element constraints propose a host rock-dominated hydrothermal system, lacking a magmatic volatile influx. The observed hydrothermal fractionation processes (fluid boiling) and the distinct metal (loid) sources (magmatic volatiles vs. host rock) represent a continuum from magmatic volatile- to host rock-dominated hydrothermal systems within the Niuatahi caldera. This leads to seafloor mineralizations with spatially selective trace element enrichments, like Te, Se, and Bi (+/- Au, Ag) in the caldera center compared to Au, Ag, Zn, Cd, and Pb at the northern caldera wall.

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How to cite

APA:

Falkenberg, J., Keith, M., Haase, K., Sporer, C., Bach, W., Klemd, R.,... Anderson, M.O. (2022). Spatial Variations in Magmatic Volatile Influx and Fluid Boiling in the Submarine Hydrothermal Systems of Niuatahi Caldera, Tonga Rear-Arc. Geochemistry Geophysics Geosystems, 23(4). https://dx.doi.org/10.1029/2021GC010259

MLA:

Falkenberg, Jan, et al. "Spatial Variations in Magmatic Volatile Influx and Fluid Boiling in the Submarine Hydrothermal Systems of Niuatahi Caldera, Tonga Rear-Arc." Geochemistry Geophysics Geosystems 23.4 (2022).

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