成矿流体与含铁围岩反应可生成大量黄铁矿并伴随金的高效沉淀，然而含Au-As-S的多元流体交代含铁碳酸盐围岩形成载金黄铁矿的矿物学过程还有待揭示。本文运用水热实验模拟了Au-As-S多元流体交代菱铁矿的成矿过程，采用X射线衍射（XRD）、拉曼光谱（Raman）、扫描电子显微镜（SEM）和电子探针显微分析（EPMA）等方法表征了菱铁矿蚀变前后的矿物学特征。结果表明：含Au-As-S的多元热液流体交代菱铁矿可生成载金黄铁矿，且黄铁矿的平均颗粒尺寸受控于初始溶液的As浓度；当初始溶液As浓度从0升至100 ppm，黄铁矿的平均颗粒尺寸减小约56%；初始溶液As浓度越高，进入黄铁矿结构中的As则越多，也更有利于流体中的Au以晶格金的形式进入黄铁矿；所形成的载金黄铁矿的Au与As含量呈现显著的正相关性，即存在As-Au耦合关系，与已报道的载金黄铁矿中的现象一致。该研究不仅深入剖析了菱铁矿在含Au-As-S的多元流体蚀变前后的矿物学演化特征，还有助于对载金黄铁矿中Au-As耦合关系成因的认识。

The Jiangnan Orogenic Belt is a world-renowned metallogenic region for Au-W-Sb mineralization, with the Wangu deposit being a representative one. Previous research has demonstrated that tungsten in this Au-W-Sb deposit is sourced from the hosting metasedimentary rocks, but the specific mineral that provides tungsten is still unclear. This study evaluates the tungsten source by conducting petrographic observations and geochemical and geochronological analyses on the rutile from the host slate the Wangu deposit. The results show that rutile from wall rocks of the Wangu deposit yields an age of 955 ± 13 Ma, which is older than both the ore-forming age of the deposit and the age of the host strata. Electron microprobe analyses (EMPA) and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) elemental analyses show that detrital rutile is enriched in elements such as Fe, Cr, V, and W, as well as high-field-strength elements (HFSE) including Nb, Ta, Zr, and Hf. The total rare earth element (ΣREE) ranges from 3.37 ppm to 156.85 ppm. The samples are generally enriched in light rare earth elements (LREEs) and exhibit distinct negative Eu anomalies. These geochemical features and a geochronological age of 955 ± 13 Ma suggest that the rutile is of detrital origin and they are possibly derived from the Grenvillian rocks. It is concluded that the detrital rutile in the metasediments could be an important source for hydrothermal tungsten enrichment.

The Bou Azzer and Bleïda deposits in the Anti-Atlas of Morocco are geographically close and occur within the same Neoproterozoic Pan-African tectonic framework, yet they host contrasting styles of metal mineralization. Bou Azzer hosts economically important Co–Ni mineral deposits linked to serpentinized ultramafic formations, whereas Bleïda is mainly characterized by Cu–Fe sulfide mineralization hosted in volcanic units. Despite their close geographic and tectonic relationship, the geological and geochemical controls responsible for these different mineralization styles remain insufficiently understood. This study integrates geological and petrographic observations with compiled published geochronological data, fluid-inclusion microthermometry, and S isotopic compositions to better understand the evolution of mineralizing systems and ore formation processes. The results suggest that Bou Azzer is a polyphase serpentinite-hosted Co-Ni hydrothermal system with high-temperature, saline fluids, and sequential arsenide and sulfarsenide deposition. Bleïda, in contrast, is associated with a structurally controlled volcanic-sedimentary copper system characterized by low-salinity hydrothermal fluids, fluid–rock interaction, and remobilization of pre-existing sulfide mineralization. Despite their contrasting mineralization styles, Bou Azzer and Bleïda exhibit broadly similar S-isotope ranges and possibly overlapping mineralization ages. Their wide isotopic variations are interpreted to reflect redox-controlled fractionation under relatively oxidizing conditions rather than differences in sulfur source. The contrasting metal assemblages were therefore probably controlled by differences in fluid–rock interaction, local redox evolution, structural setting, and metal precipitation mechanisms. The genetic model integrating magmatism, structural deformation, and hydrothermal mineralization is proposed in this study.

The Xiangshan ore field is characterized by extensive alkali metasomatism, which represents the early-stage hydrothermal event before the acidic metasomatism during major U mineralization. However, the mineralogical and geochemical characteristics of alkali metasomatism, as well as its association with uranium mineralization, remain poorly understood. This study evaluates these scientific problems by conducting petrographic and geochemical analyses on feldspar, together with thermodynamic modeling. Hydrothermal feldspars are present as veinlets, differing from the magmatic ones with granular and subhedral structures. Hydrothermal albites have lower Na but higher K content than magmatic ones, while hydrothermal K-feldspars have lower K but higher Na content than magmatic ones. In addition, hydrothermal feldspars are significantly depleted in Ca and Sr, likely associated with the consumption of Ca in fluids by fluorite and calcite precipitation. Furthermore, alkali metasomatism is accompanied by intense hematitization, indicating the oxidized properties of ore fluids that are favorable for uranium transport. Thermodynamic modeling further demonstrates that continuous K⁺ consumption during fluid–rock interaction leads to a pH increase in the fluid, which is buffered by quartz–muscovite–K-feldspar (QMF). Given that quartz solubility is positively correlated with pH, this process induces extensive quartz dissolution in the host rocks. Such dissolution significantly enhances the porosity and permeability of the host rocks, creating ideal physical traps for the subsequent accumulation of uranium-bearing fluids. Consequently, alkali-metasomatized rocks associated with quartz dissolution and hematitization serve as critical indicators for regional uranium exploration.