中国科学院地球化学研究所Linbo Shang团队研究了温度高达300°C时热液中铜形态的原位拉曼光谱。2025年5月20日出版的《地球化学学报》杂志发表了这项成果。

铜矿床的形成与热液作用密切相关。了解铜在热液流体中的迁移有助于重建成矿过程和破译矿床成因。铜主要以Cu⁺和Cu²⁺的形式存在于水热溶液中，其相互转化受氧化还原条件控制。在富含氯化物的地质流体中，Cu-Cl络合物被认为是铜运输的关键。然而，Cu-Cl配合物在不同水热条件下的具体类型和价态转变仍然知之甚少。

研究组采用原位拉曼光谱系统在25-300°C的饱和蒸汽压下分析Cu+HCl和CuCl₂+ K₂S₂O₃/H₂体系，阐明了温度、Cl^-浓度和氧化还原条件对铜形态的影响。。在Cu +HCl体系中，铜溶解为单价Cu-Cl配合物。在高温下（>200°C）下，[CuCl₂]⁻是优势种，而[CuCl₃]²⁻在较低的温度和较高的盐酸浓度下变得普遍。

对于Cu²⁺–Cl体系，优势物种从[Cu（H₂O）_n]²⁺（<50°C）转变为[CuCl₄]²⁻（100°C），并在300°C下进一步转变为[CuCl]⁺和[CuCl₂]⁰。还原剂（K₂S₂O₃/H₂）的引入促进了Cu²⁺→Cu⁺还原，从而稳定Cu⁺-Cl络合物并诱导部分铜沉淀。研究组观察到的富氯化物热液中铜的行为表明，高温氧化液促进了铜的活化，而冷却和氧化还原变化促进了沉积和矿石矿物的形成。

附：英文原文

Title: In situ Raman spectroscopic investigation of copper speciation in hydrothermal fluids at temperatures up to 300 °C

Author: Wang, Zhenglong, Shang, Linbo, Chou, I-Ming, Chen, Chen, Zhou, Yunhe, Li, Jianguo, Jiang, Ziqi, Gao, Xinwei, Wan, Ye

Issue&Volume: 2025-05-20

Abstract: The formation of copper deposits is closely related to hydrothermal processes. Understanding the migration of copper in hydrothermal fluids aids in reconstructing mineralization processes and deciphering deposit genesis. Copper primarily exists as Cu+ and Cu2+ in hydrothermal solutions, with redox conditions governing their interconversion. In chloride-rich geological fluids, Cu–Cl complexes are considered critical for copper transport. However, the specific types and valence transitions of Cu–Cl complexes under varying hydrothermal conditions remain poorly understood. This study employed in situ Raman spectroscopy to systematically analyze Cu+HCl and CuCl2+K2S2O3/H2 systems under saturated vapor pressure at 25–300 °C, elucidating the effects of temperature, Cl concentration, and redox conditions on copper speciation. In the Cu+HCl system, copper dissolved as monovalent Cu–Cl complexes. At high temperatures (>200 °C), [CuCl2] is the dominated species, whereas [CuCl3]2 becomes prevalent at lower temperatures and higher HCl concentrations. For the Cu2+–Cl system, the dominant species transitioned from [Cu(H2O)n]2+ (<50 °C) to [CuCl4]2 (100 °C) and further to [CuCl]+ and [CuCl2]0 at 300 °C. The introduction of reducing agents (K2S2O3/H2) facilitated Cu2+→Cu+ reduction, thereby stabilizing Cu+–Cl complexes and inducing partial copper precipitation. The behavior of copper in chloride-rich hydrothermal fluids observed in this study indicates that high-temperature oxidizing fluids facilitate Cu mobilization, while cooling and redox changes promote deposition and ore minerals formation.

DOI: 10.1007/s11631-025-00781-y

Source: https://link.springer.com/article/10.1007/s11631-025-00781-y