TY - JOUR TI - Trace-element compositions of sulfides from inactive Tianzuo hydrothermal field, Southwest Indian Ridge: Implications for ultramafic rocks hosting mineralization AU - Ding, Teng AU - Wang, Jia AU - Tao, Chunhui AU - Dias, Ágata Alveirinho AU - Liang, Jin AU - Wang, Yuan AU - Chen, Jie AU - Wu, Bin AU - Huang, Hui T2 - Ore Geology Reviews AB - The recently explored inactive Tianzuo hydrothermal field, in the amagmatic segment of the ultraslow-spreading Southwest Indian Ridge (SWIR), is closely associated with detachment faults. In this site, sulfide minerals are hosted by serpentine-bearing ultramafic rocks and include high-temperature (isocubanite, sphalerite, and minor pyrrhotite) and low-temperature (pyrite I, marcasite, pyrite II, and covellite) phases. In this study, trace-element concentrations of isocubanite and pyrite II were used to elucidate mineralization processes in ultramafic rocks hosting sulfides. Results show that isocubanite is enriched in metals such as Cu, Co, Sn, Te, Zn, Se, Pb, Bi, Cd, Ag, In, and Mn, and pyrite II is enriched in Mo and Tl. The marked enrichment in Te, Cu, Co, and In in isocubanite (compared with Se, Zn, Ni, and Sn, respectively) is most likely due to the contribution of magmatic fluids from gabbroic intrusions beneath the hydrothermal field. The intrusion of gabbroic magmas would have enhanced serpentinization reactions and provided a relatively oxidizing environment through the dissolution of anhydrite precipitated previously in the reaction zone, within high temperature and low pH conditions. This might have facilitated the extraction of metals by initial hydrothermal fluids, leading to the general enrichment of most metals in isocubanite. Metals in pyrite II have compositions similar to those of isocubanite, except for strong depletion in magmatically derived Te, Cu, Co, and In. This means that serpentinization processes had a dominating role in pyrite II precipitation as well. The enrichment of pyrite II in Mo and Tl is also indicative of seawater contribution in its composition. The study concludes that serpentinization reactions contribute effectively both to high- and low-temperature sulfide mineralization at Tianzuo hydrothermal field, with gabbroic intrusions further promoting high-temperature sulfide mineralization, providing additional metals, fluids and heat. In contrast, low-temperature sulfide mineralization occurred during the cooling of gabbroic intrusions, with decreasing rates of serpentinization reactions and a significant influence of seawater. DA - 2022/01/01/ PY - 2022 DO - 10.1016/j.oregeorev.2021.104421 DP - ScienceDirect VL - 140 SP - 104421 J2 - Ore Geology Reviews LA - en SN - 0169-1368 ST - Trace-element compositions of sulfides from inactive Tianzuo hydrothermal field, Southwest Indian Ridge UR - https://www.sciencedirect.com/science/article/pii/S0169136821004479 Y2 - 2022/09/21/13:41:17 KW - SWIR KW - Serpentinization KW - Sulfide KW - Tianzuo KW - Trace-element KW - Ultramafic rocks ER - TY - JOUR TI - Sulfur isotopic compositions of sulfides along the Southwest Indian Ridge: implications for mineralization in ultramafic rocks AU - Dias, Ágata AU - Ding, Teng AU - Tao, Chunhui AU - Liang, Jin AU - Chen, Jie AU - Wu, Bin AU - Ma, Dongsheng AU - Zhang, Rongqing AU - Wang, Jia AU - Liao, Shili AU - Wang, Yuan AU - Yang, Weifang AU - Liu, Jia AU - Li, Wei AU - Zhang, Guoyin AU - Huang, Hui T2 - Mineralium Deposita DA - 2020/10/31/ PY - 2020 DO - 10.1007/s00126-020-01025-0 DP - DOI.org (Crossref) J2 - Miner Deposita LA - en SN - 0026-4598, 1432-1866 ST - Sulfur isotopic compositions of sulfides along the Southwest Indian Ridge UR - http://link.springer.com/10.1007/s00126-020-01025-0 Y2 - 2021/03/30/07:28:44 ER - TY - JOUR TI - Serpentinization and its implications for ultramafic-hosted sulfide mineralization: A case study at the Tianzuo hydrothermal field, 63.5°E, Southwest Indian Ridge AU - Ding, Teng AU - Dias, Ágata Alveirinho AU - Wang, Jia AU - Tan, Tingting AU - Liang, Jin AU - Wu, Bin AU - Tao, Chunhui T2 - Marine Geology AB - Reaction of ultramafic rocks with seawater and subsequent serpentinization has been considered one of the most important factors controlling the formation of ultramafic-hosted seafloor massive sulfide (UM-SMS) deposits. However, the mineralization processes responsible for these deposits remain poorly understood, in particular because they are less abundant as compared with their basaltic counterparts. In this work, serpentinites with different alteration grades collected at the Tianzuo hydrothermal field (THF), Southwest Indian Ridge, were studied. Mineralogical and chemical analyses were performed in the secondary opaque minerals resulting from serpentinization to understand the role of this process during the formation of UM-SMS deposits. Our results show that these opaque minerals mainly consist of magnetite, hematite, pentlandite, and minor pyrite, suggestive of high but varying oxygen and sulfur fugacities. The hematite is characterized by an enrichment in Mg, Si, Ni, and Co as compared with magnetite. Pentlandite associated with hematite has elevated and consistent Ni contents as compared with that associated with magnetite. These results indicate that breakdown and decomposition of primary silicate and sulfide minerals during serpentinization has controlled the sources of ore-forming materials. Concentrations of Te are variable and show a positive correlation with Ni in pentlandite associated with magnetite or hematite, suggesting that gabbroic intrusions provided additional material to the hydrothermal system. Oxidation and sulfidation conditions are ideal for the formation of trisulfur ion S3− in THF, which can significantly improve the capability of hydrothermal fluids for leaching ore-forming metals from the wall rocks, promoting the formation of THF. In addition of reduced systems, hydrothermal fluids with high oxygen and sulfur fugacities triggered by extensive seawater infiltration can most likely also develop in ultramafic-hosted systems. These results suggest that the areas with well-developed fractures are promising candidates for further exploration of UM-SMS deposits along mid-oceanic ridges. DA - 2023/01/01/ PY - 2023 DO - 10.1016/j.margeo.2022.106969 DP - ScienceDirect VL - 455 SP - 106969 J2 - Marine Geology LA - en SN - 0025-3227 ST - Serpentinization and its implications for ultramafic-hosted sulfide mineralization UR - https://www.sciencedirect.com/science/article/pii/S0025322722002407 Y2 - 2022/12/25/11:11:31 KW - Opaque minerals KW - Oxidation and sulfidation KW - Sulfide mineralization KW - Tianzuo hydrothermal field KW - Ultramafic rocks ER -