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

• Published in: Geochimica et cosmochimica acta 2024-05, Vol.373, p.52-67
• Main Authors: Falkenberg, Jan J., Keith, Manuel, Haase, Karsten M., Klemd, Reiner, Kutzschbach, Martin, Grosche, Anna, Scicchitano, Maria Rosa, Strauss, Harald, Kim, Jonguk
• Format: Article
• Language: English
• Subjects: Black smokers; coupled SIMS δ34S and LA-ICP-MS trace element data; In-situ sulfide chemistry; Magmatic fluids; Magmatic volatile phase; Pyrite; Submarine hydrothermal systems
• ISSN: 0016-7037; 1872-9533
• DOI: 10.1016/j.gca.2024.03.026

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