Sulfur isotopic compositions of sulfides along the Southwest Indian Ridge: implications for mineralization in ultramafic rocks

Sulfur isotopes of hydrothermal vent fossils and insights into microbial sulfur cycling within a lower Paleozoic (Ordovician‐early Silurian) vent community

“…In contrast, our δ 34 S results are as low as −7‰ (Table 1). They are within the range of values reported by Ding et al (2021) from the Southwest Indian Ridge, where pyrite δ 34 S values of −3.6‰ to −23.8‰ were interpreted to suggest microbial sulfate reduction. Thus, our results also indicate a potential biological influence on pyrite sulfur isotope composition.…”

“…At equilibrium conditions, pyrite should have δ 34 S values greater than that of associated vent fluid, but in practice, the δ 34 S values are often lighter, possibly as a result of precipitation from lower temperature fluids (Rouxel et al, 2004) or via thiosulfate intermediates (Ono et al, 2007). δ 34 S values of hydrothermal vent sulfide minerals below approximately −4‰ have been interpreted to indicate contributions from microbial sulfate reduction (MSR) (Ding et al, 2021; Eickmann et al, 2020; Peters et al, 2010). MSR is considered to be a particularly important process at sedimented hydrothermal vents (Fowler et al, 2019; McDermott et al, 2015) and in the hydrothermal vent subsurface, where it occurs during the low‐temperature alteration of oceanic crustal rocks (Ono et al, 2012; Rouxel et al, 2004).…”

Ore genesis of the Huangshaping skarn W–Mo–Pb–Zn deposit, southern Hunan Province, China: insights from in situ LA-MC-ICP-MS sulphur isotopic compositions

“…Sulphur isotopic compositions of sulphides can be indicators of the sources of sulphur and evolution of the hydrothermal fluids from which these minerals precipitated (e.g. Ault & Williams-Jones, 2004;Ding et al 2016bDing et al , 2020. In addition to Huangshaping deposit Mo and Pb-Zn mineralization, in which sulphides are the dominant ore-forming minerals, W mineralization in the deposit also has a close relationship with sulphides, including the observed coexistence of wolframite with columbite and molybdenite in quartz veins cross-cutting the granite porphyry (Ding et al 2017), and both scheelite and arsenopyrite coexist in quartz veins within sericite-quartz alteration (Fig.…”

Seafloor Hydrothermal Activity around a Large Non-Transform Discontinuity along Ultraslow-Spreading Southwest Indian Ridge (48.1–48.7° E)

“…The SWIR is characterized by a starved magma supply; however, locally enhanced magmatism caused by focused melt injection and sufficient permeability generated by tectonic activity provide conditions to drive hydrothermal circulation [9]. The confirmed hydrothermal fields along the SWIR occur on segment centers, including Duanqiao [55], Tiancheng [56] and Mount Jourdanne [57], and on detachment faults of the rift valley walls, including Yuhuang [58], Longqi [9] and Tianzuo [29]. Our newly inferred hydrothermal anomaly sites based on plume mapping and the previously reported SDF occupy various morphotectonic settings (white boxes in Figure 1b) around the large NTD area (Figures 7-9).…”

“…In contrast to slow OSRs, the size of NTDs along ultraslow OSRs is generally larger due to the more starved magma supply at segment ends and the larger spacing between spreading cells [22,28], and thus they account for a certain fraction of the total ridge length. Due to limited surveys and complicated geological settings, however, only one inactive ultramafic-hosted hydrothermal field on a detachment fault (i.e., Tianzuo [29]) has been confirmed at NTDs along ultraslow OSRs. It remains unclear along ultraslow OSRs which factors contribute to the occurrence of hydrothermal activity at NTDs and whether they could be potential areas in fertilizing hydrothermal activities.…”