Four new hydrothermal vent fields were discovered on the slow spreading Central Indian Ridge (8–12°S; Segments 1–3), all located off‐axis on abyssal hill structures or Ocean Core Complexes (OCCs). Each site was characterized using seafloor observation (towed camera system), plume chemistry (Fe, Mn, and CH₄; Conductivity, Temperature, and Depth sensor [CTD]/Miniature Autonomous Plume Recorder [MAPR]), and rock sampling (TVgrab/dredges). Different styles of venting on each segment reflect different geological settings, rock types, likely heat sources, and fluid pathways. The segment 1 field was located on the western flank of the axial valley at the base of OCC‐1‐1. High‐temperature venting was inferred from plume characteristics and extensive seafloor sulfide mineralization, but only diffuse venting was observed. This site appears to be a magmatic‐influenced basaltic‐hosted system despite its off‐axis location. Two low‐temperature diffusely venting sites were located on abyssal hills 6 and 9 km off‐axis on Segment 2. Plume particle, metal, and CH₄ concentrations were all very low, suggesting dilution of hydrothermal fluids by intrusion of seawater into the highly permeable flank area fault zone. The “Onnuri Vent Field” (OVF), located at the summit of OCC‐3‐2, vented clear, low‐temperature fluids supporting abundant vent organisms (21 macrofaunal taxa). The plume particle signal was low to absent, but strong ORP anomalies correlated with high CH₄ and low metal concentrations. Sulfide mineralization was present, which suggests both serpentinization and magmatic/lithospheric influence on fluid composition. The detachment fault is the likely pathway for hydrothermal fluid circulation at this off‐axis location. These new vent field discoveries, especially the OVF, contribute valuable information toward understanding Indian Ocean hydrothermal systems and their ecology/biogeography.

中文翻译：

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在8-12°S沿中部印度洋脊发现活跃的热液排放场

在缓慢蔓延的中部印度洋脊（8–12°S； 1–3段）上发现了四个新的热液喷口，它们都偏心位于深渊丘陵结构或大洋核心群（OCC）上。使用海底观测（拖曳相机系统），羽流化学（Fe，Mn和CH ₄; 电导率，温度和深度传感器[CTD] /微型自主羽记录仪[MAPR]）以及岩石采样（TVgrab /挖泥机）。每个段上不同的放空方式反映了不同的地质环境，岩石类型，可能的热源和流体路径。段1场位于OCC-1-1底部轴向谷的西侧。从羽状特征和广泛的海底硫化物矿化推断出高温放空，但仅观察到弥散放空。尽管它位于离轴位置，但它似乎是一个受岩浆影响的玄武岩系。在段2的离轴深6和9 km处，有两个低温扩散通风点。羽状颗粒，金属和CH ₄浓度都非常低，表明海水侵入高渗透性侧翼断层带会稀释热液。位于OCC-3-2峰顶的“ Onnuri通风场”（OVF）可以排出透明的低温流体，以支持丰富的排放生物（21个大型动物分类群）。羽状颗粒信号低至不存在，但强烈的ORP异常与高CH ₄相关和低金属浓度。存在硫化物矿化作用，这表明蛇纹石化作用和岩浆/岩圈对流体成分的影响。脱离断层是该离轴位置热液循环的可能途径。这些新的发泄场发现，尤其是OVF，为理解印度洋热液系统及其生态/生物地理学提供了宝贵的信息。