(Table T1) Geochemistry of anhydrite separates from hydrothermal veins and vug fills of ODP Leg 193 sites, PACMANUS field@en

Sr and S isotope data as well as trace element data for anhydrite samples from Sites 1188 and 1189 in the PACMANUS hydrothermal area are presented here. 87Sr/86Sr ratios range from 0.7050 to 0.7086, suggesting that the anhydrites precipitated from fluids that were variably influenced by entrained seawater (0%–89%). d34S values range between 18.1 per mil and 22.5 per mil, indicating the main source of sulfate is seawater that may be affected to small extents by sulfide oxidation or magmatic sulfate input (d34S < 21 per mil) and minor sulfate reduction (d34S > 21 per mil). Rare earth element (REE) concentrations are highly variable, particularly at Site 1188. Chondrite-normalized REE pattern shapes comprise light REE enriched, light REE depleted, mid-REE enriched, and variable positive and negative Eu anomalies. Significant correlations between trace element and isotopic compositions are lacking. Anhydrite from Site 1188, a site of diffuse venting, has systematically lower d34S and higher Sr contents and somewhat lower average 87Sr/86Sr than anhydrite from Site 1189. This is possibly a consequence of the different fluid flow regime with diffuse flow at Site 1188 and focused flow at Site 1189.本文展示了PACMANUS热液区1188与1189站位硬石膏样品的锶（Sr）、硫（S）同位素数据及微量元素数据。87锶/86锶（87Sr/86Sr）比值介于0.7050至0.7086之间，表明该区域硬石膏由混入0%~89%海水的流体沉积形成。δ34S值介于18.1‰与22.5‰之间，指示硫酸盐的主要来源为海水，其可能受硫化物氧化或岩浆硫酸盐输入（δ34S＜21‰）的轻度影响，同时伴随微弱的硫酸盐还原作用（δ34S＞21‰）。稀土元素（Rare Earth Element, REE）含量差异显著，尤其在1188站位更为突出。球粒陨石标准化稀土元素配分模式可分为轻稀土富集型、轻稀土亏损型、中稀土富集型，且存在不同程度的铕（Eu）正异常与负异常。微量元素组成与同位素组成之间未发现显著相关性。与1189站位的硬石膏相比，以弥散式喷溢为特征的1188站位硬石膏的δ34S值系统性偏低，锶含量更高，且平均87Sr/86Sr比值略低。这一差异可能源于两处站位不同的流体流动机制：1188站位为弥散式流体流动，而1189站位为集中式流体流动。