Pyrite trace element proxies for magmatic volatile influx in submarine subduction-related hydrothermal systems

Falkenberg J, Keith M, Haase K, Klemd R, Kutzschbach M, Grosche A, Scicchitano MR, Strauss H, Kim J (2024)

Publication Type: Journal article

Publication year: 2024

Journal

Book Volume: 373

Pages Range: 52-67

DOI: 10.1016/j.gca.2024.03.026

Abstract

Seafloor massive sulfides are modern analogues to ancient volcanogenic massive sulfide deposits, which are particularly enriched in volatile and precious metals (e.g., Te, Au, Ag, Cu, Bi, Se) in subduction-related settings. However, the sources of metals are still poorly constrained, and it remains elusive, whether magmatic volatile influx controls their distribution in submarine hydrothermal systems on the plate tectonic-scale. Here, we demonstrate, for the first time, that Te, As, and Sb contents as well as related Te/As and Te/Sb ratios vary systematically with the δ³⁴S composition of pyrite and native S, as reported by high-resolution coupled SIMS δ³⁴S and trace element LA-ICP-MS micro-analysis. The better correlation of element ratios (Te/As, Te/Sb) opposed to trace element contents (e.g., Te) with δ³⁴S in pyrite demonstrates that element ratios provide a more robust record of magmatic volatile influx than their absolute contents. On this basis, we define a quantitative threshold of high Te/As (>0.004) and Te/Sb (>0.6) ratios in pyrite that are indicative of magmatic volatile influx to submarine subduction-related hydrothermal systems. Two-component fluid mixing simulations further revealed that <5 % of magmatic volatile influx drastically changes the Te/As (and Te/Sb) ratio of the modelled fluid, but only slightly changes its δ³⁴S composition. This suggests that Te/As and Te/Sb ratios are more sensitive to a magmatic volatile influx into seawater-dominated hydrothermal systems than δ³⁴S signatures if the magmatic volatile influx was low. Beyond this, our results demonstrate that magma-derived fluid mixing with seawater only has a negligible effect on the magmatic volatile record of Te/As and Te/Sb, while the S isotope system is prone for seawater overprinting leading to commonly ambiguous source signatures. Thus, Te/As and Te/Sb systematics in pyrite provide a robust proxy to evaluate the contribution of magmatic volatiles to submarine hydrothermal systems from the grain- to plate tectonic-scale.

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Involved external institutions

Technische Universität Berlin Germany (DE) Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ Germany (DE) Westfälische Wilhelms-Universität (WWU) Münster Germany (DE) Korea Institute of Ocean Science and Technology (KIOST) / 한국해양연구원 Korea, Republic of (KR)

How to cite

APA:

Falkenberg, J., Keith, M., Haase, K., Klemd, R., Kutzschbach, M., Grosche, A.,... Kim, J. (2024). Pyrite trace element proxies for magmatic volatile influx in submarine subduction-related hydrothermal systems. Geochimica Et Cosmochimica Acta, 373, 52-67. https://doi.org/10.1016/j.gca.2024.03.026

MLA:

Falkenberg, Jan, et al. "Pyrite trace element proxies for magmatic volatile influx in submarine subduction-related hydrothermal systems." Geochimica Et Cosmochimica Acta 373 (2024): 52-67.

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