Multi-source hydrothermal mineralisation in the ultramafic-hosted Mirae-2 vent field, Central Indian Ridge

• DOI: 10.1007/s00126-025-01347-x
• Publication Date: 2025-01-23T09:22:07Z
• Authors: Sun Ki Choi; Jonguk Kim; Sang Joon Pak; Wonnyon Kim; Hwimin Jang; Ryoung Gyun Kim
• Keywords: Ultramafic rock; Mineral resource classification

Modern seafloor massive sulfide deposits distributed along mid-ocean ridges are typically classified as ridge basalt- and ultramafic-hosted types, based on mineralogical geochemical characteristics that result from the different water–rock interactions between two substrates. However, Mirae-2 vent field (MVF-2) Central Indian Ridge, which was newly discovered slope of an oceanic core complex, deviates this common concept. Mineralogical data indicate formation chimney mound samples primarily controlled by changes in physicochemical fluid conditions (temperature, pH, ƒS2, ƒO2) driven varying degrees fluid–seawater mixing. In particular, prevalence assemblages (pyrrhotite + isocubanite Fe-rich sphalerite), Cu–Au-rich mineralisation, enrichments Co (average = 1109 ppm) Sn (203 similar to those other deposits, but high amounts barite galena, Ba (> 100,000 Pb (up 8.91 wt%) reflect contribution distinct metal sources than ultramafic The extremely positive δ34S values pyrite 15.1 ± 1.7‰) pyrrhotite (+ 6.37 0.5‰) metals S MVF-2 were likely derived serpentinised rocks with intense mixing fluids seawater, whereas unusually radiogenic isotope ratios sphalerite (206Pb/204Pb 18.531–18.559, 207Pb/204Pb 15.540–15.564, 208Pb/204Pb 38.632–38.693) suggest enriched basalts (i.e., basalts) near axis also had important role supply some (Pb Ba) fluids. Our results multi-stage fluid-rock reactions basalt subsequent produced multi-source hydrothermal fluids, thereby resulting mineralogy geochemistry compared deposits.