Abstract—

The sulfur isotope composition of single sulfide grains has been studied taking into account their paragenetic sequence in the samples collected from three hydrothermal fields (Logatchev, Krasnov, and Rainbow), located in the northern part of the Mid-Atlantic Ridge. The δ³⁴S values of sulfides are +3.9 to +6, +7.1 to +9.8, and +2.1 to +8.4 ‰ in the Logatchev, Krasnov, and Rainbow fields, respectively. Late-generation sulfides within the studied domains (1–10 mm) of the samples are enriched in ³⁴S isotope relative to early generations, and the sulfur isotope composition shows no relationship with the composition of sulfide minerals. In single grains of hydrothermal barite, the δ³⁴S values exceed the generally accepted range for modern seawater sulfates. A model of the sulfur isotope fractionation in the hydrothermal system is proposed, based on the assumption of thermogenic sulfate reduction during fluid–rock interaction in the system, which is closed with respect to fluid. The model also takes into account simultaneous sulfur leaching from host rocks, the proportion of released sulfur from which depends on the progress of thermogenic sulfate reduction. Application of this model explains some well-known contradictions found in studying the sulfur isotope composition of sulfides from other hydrothermal fields in the World Ocean.

中文翻译：

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热液海底系统中硫化物生成过程中的硫同位素分馏：以大西洋中脊的Logatchev，Krasnov和Rainbow热液场为例

摘要—

考虑到从位于大西洋中脊北部的三个热液田（Logatchev，Krasnov和Rainbow）收集的样品中的单种硫化物序列，研究了单硫化物颗粒的硫同位素组成。的δ ³⁴硫化物的价值观分别3.9至6，7.1至9.8，和2.1至8.4‰在Logatchev，克拉斯诺夫，和彩虹领域，都。相对于早期世代，样品研究范围内的后期世代硫化物（1-10 mm）富含³⁴ S同位素，并且硫同位素组成与硫化物矿物的组成无关。在热液重晶石的单个颗粒时，δ ³⁴S值超过了现代海水硫酸盐的公认范围。提出了一个水热系统中硫同位素分馏的模型，该模型基于系统中流体与岩石相互作用期间生热硫酸盐还原的假设，该流体相对于流体是封闭的。该模型还考虑了从宿主岩中同时浸出硫的问题，硫的释放比例取决于生热硫酸盐还原的进度。该模型的应用解释了在研究世界海洋其他热液领域的硫化物的硫同位素组成时发现的一些众所周知的矛盾。