近日，昆明理工大学韩润生团队报道了云南大红山铜-铁-钴多金属矿床钴的成矿机制。这一研究成果于2025年12月29日发表在《地球化学学报》上。

大红山铜铁钴矿床作为康滇铜铁多金属带的关键实例，呈现火山喷流沉积、变质作用及热液叠加等多种矿化形式。该矿床富含铜、铁、钴、金、钼等元素，且受构造控制显著。尽管近期研究揭示了矿石中钴元素的高度差异性富集现象，但其赋存状态、富集规律与作用机制尚不明确。研究组采用电子探针显微分析仪与激光剥蚀电感耦合等离子体质谱技术，通过对钴矿物、黄铁矿、黄铜矿及磁铁矿等关键矿石矿物的分析，明确了钴的富集特征：钴矿物含钴量达31.00%–34.26%；黄铁矿通过类质同象替代作用含钴0.01%–5.38%；磁铁矿包体中钴含量为55.37–226 ppm，黄铜矿包体中为0–290 ppm。

在280米中段岩相填图揭示出明显的空间分异规律：硫化矿石钴富集程度最高（平均261.63 ppm），其次为氧化矿石（42.7–241.9 ppm）、交代钠化凝灰岩（18.7–148.1 ppm）、石榴石黑云母片岩（80.0–143.3 ppm）、碳酸盐矿物（21.1–70.7 ppm）及石英（2.5–59.8 ppm）。从背斜核部（勘探线B136–B120）向翼部钴含量递减的趋势，凸显了底巴都背斜构造对矿化的控制作用。

成矿模型构建了三级富集过程：（1）火山喷流沉积阶段，含钴氯配合物在岩浆流体与海水混合及氧化事件中分解，形成钴矿物及阶段Ⅰ黄铁矿的初始富集；（2）区域变质阶段（290–330°C，盐度16%–32%），通过流体萃取与重结晶实现钴的再活化，并以类质同象形式进入阶段Ⅱ黄铁矿；（3）热液叠加阶段在低温（245.1–92.3°C）和差异氧化还原条件下，沿裂隙形成分带矿物组合（[黄铁矿+黄铜矿]→斑铜矿→辉铜矿），钴元素在该阶段参与阶段Ⅲ黄铁矿的形成。

附：英文原文

Title: Mineralization Mechanism of Cobalt in the Dahongshan Copper-Iron-Cobalt Polymetallic Deposit in Yunnan, China

Author: Kang, Xuhao, Han, Runsheng, Zhao, Yanwei, Zhao, Dong, Gong, Hongsheng, Meng, Liuqing, Mao, Xing, Sun, Long, Zhou, Yinkang

Issue&Volume: 2025-12-29

Abstract: The Dahongshan Cu–Fe–Co deposit, a key example of the Kangdian Cu–Fe polymetallic belt, features several forms of mineralization, including volcanic exhalative-sedimentation, metamorphism, and hydrothermal superposition. This deposit is rich in Cu, Fe, Co, Au, and Mo and exhibits strong structural control. Although recent studies have demonstrated highly variable enrichment of Co in ores, knowledge about its occurrence, enrichment patterns, and mechanisms is lacking. This study examined these aspects using an electron probe micro-analyzer and laser ablation inductively coupled plasma mass spectrometry. This revealed clear Co enrichment in key ore minerals, indicated by the presence of cobaltite, pyrite, chalcopyrite, and magnetite. Cobaltite comprised 31.00%–34.26% of the Co detected. Pyrite, indicating isomorphic substitution by Co, accounted for 0.01%–5.38% of the Co detected. Lower Co concentrations were detected in inclusions in magnetite (55.37 ppm–226 ppm) and chalcopyrite (0–290 ppm). Mapping of lithofacies at the 280 m level revealed clear spatial differences. Cobalt enrichment was highest in sulfide ores, averaging 261.63 ppm, followed by oxide ores (42.7 ppm–241.9 ppm), metasomatic albitized tuff (18.7 ppm–148.1 ppm), garnet-biotite schist (80.0 ppm–143.3 ppm), carbonate minerals (21.1 ppm–70.7 ppm), and quartz (2.5 ppm–59.8 ppm). Co-reduction from the anticlinal core (exploration lines B136–B120) to the edges highlights how the Dibadu anticline affects the structure. The metallogenic model outlines a three-stage enrichment process: (1) Volcanic exhalative sedimentation occurs, and Co forms sulfides as Co–Cl (CoCl42-) complexes break down. This breakdown occurs when igneous fluids mix with seawater and during oxidation events, resulting in significantly enriched cobaltite and stage pyrite (I). (2) The second stage involves regional metamorphism at 290–330 °C and 16%–32% salinity, which helps to remobilize Co via fluid extraction and recrystallization, thereby adding Co to stage pyrite (II) via isomorphism. (3) Hydrothermal superposition creates zoned mineral groups ([pyrite+chalcopyrite]→bornite→chalcocite) along fractures at lower temperatures (245.1–92.3 °C) and with varying redox states. In this stage, the presence of Co supports stage (III) pyrite formation.

DOI: 10.1007/s11631-025-00835-1

Source: https://link.springer.com/article/10.1007/s11631-025-00835-1