COHS深部板块流体中硫歧化作用驱动地幔楔氧化，这一成果由意大利都灵大学Andrea Maffeis等人合作取得。这一研究成果发表在2024年3月20日出版的国际学术期刊《科学进展》上。

研究人员应用电解流体热力学模拟了偏碳酸盐沉积物中黄铁矿的溶解行为，作为P、T和岩石氧化还原态的函数，条件为4.3千兆帕和730°C。在亚弧深度和铁橄榄石-磁铁矿-石英氧缓冲层的氧化还原条件下，黄铁矿的溶解通过歧化作用释放流体中的氧化硫，生成硫酸盐、亚硫酸氢盐和硫化物种类。

这些发现表明，在深度大于100km的俯冲板块内，氧化的、富含硫的碳-氧-氢-硫(COHS)流体的形成与板块的氧化还原状态无关，尤其是当碳酸盐稳定时，硫在氧化地幔楔时可能比伴随的溶解碳更有效。

据介绍，火山弧脱气的硫需要俯冲带流体释放溶解的硫酸盐离子(S⁶⁺)，与碳一起氧化亚弧地幔，但人们对亚弧深度俯冲流体中的硫形态的研究仍不清楚。

附：英文原文

Title: Sulfur disproportionation in deep COHS slab fluids drives mantle wedge oxidation

Author: Andrea Maffeis, Maria Luce Frezzotti, James Alexander Denis Connolly, Daniele Castelli, Simona Ferrando

Issue&Volume: 2024-03-20

Abstract: Sulfur degassed at volcanic arcs calls for dissolved sulfate ions (S⁶⁺) released by subduction-zone fluids, oxidizing (in association with carbon) the subarc mantle, but sulfur speciation in subduction fluids at subarc depths remains unclear. We apply electrolytic fluid thermodynamics to model the dissolution behavior of pyrite in metacarbonate sediments as a function of P, T and rock redox state up to 4.3 gigapascals and 730°C. At subarc depth and the redox conditions of the fayalite-magnetite-quartz oxygen buffer, pyrite dissolution releases oxidized sulfur in fluids by disproportionation into sulfate, bisulfite, and sulfide species. These findings indicate that oxidized, sulfur-rich carbon-oxygen-hydrogen-sulfur (COHS) fluids form within subducting slabs at depths greater than 100 kilometers independent from slab redox state and that sulfur can be more effective than the concomitantly dissolved carbon at oxidizing the mantle wedge, especially when carbonates are stable.

DOI: adj2770

Source: https://www.science.org/doi/10.1126/sciadv.adj2770