Kang Hongbin, Liu Yin, Hu Kai, Han Shanchu
State Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao, Shandong 266580, PR China.
State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, China.
ACS Omega. 2024 Sep 12;9(38):39365-39386. doi: 10.1021/acsomega.4c02165. eCollection 2024 Sep 24.
The Shuiyindong deposit is one of the ultralarge Carlin-type gold deposits in Southwest Guizhou Province, China. Gold mineralization mainly occurs in the Permian Longtan Formation and the early Triassic Yelang Formation. It is controlled by both strata and faults. Detailed studies of the mineralogy and geochemistry characteristics of the Shuiyindong deposit are conducted to investigate the ore-forming process. Arsenian pyrite and arsenopyrite are the main Au-hosting minerals. Three types of pyrite can be recognized, including euhedral and subhedral pyrite, framboidal pyrite, and bioclastic pyrite. The euhedral and subhedral pyrite is the main Au-hosting type. The Au appears as a solid solution (Au) and natural nanoscale gold (Au) in the sulfide minerals. The Co/Ni ratios of sulfides (0.07-3.13) reveal that the ore-forming fluids were mainly affected by hydrothermal activity, but magmatic activity cannot be excluded. Organic matter in the ores is abundant (0.11-3.04%), which might provide sulfur for pyrite and favor an increase in the porosity and permeability of the host rocks by releasing organic acids. The REE and trace element results suggest that halogens (F and Cl) were contained in the reducing magmatic hydrothermal fluids. The sulfur isotopic data (from -8.64‰ to 27.17‰) suggest that the source of sulfur is complicated and is probably a combination of a magmatic source, the reduction of marine sulfate, and bacterial sulfate reduction. The Pb isotopic data of the sulfides indicate that Pb is from a mixture of crust and mantle sources. The obvious enrichment zones exist along the boundary faults in the geochemical map of As, implying that As may originate from the deep crust and then move to the strata with basinal fluids. By combining these results, it can be inferred that the ore-forming fluids were a mixture of basinal and deep source fluids. A probable ore-forming model of the Shuiyindong gold deposit is established.
水银洞矿床是中国贵州省西南部超大型卡林型金矿床之一。金矿化主要发生在二叠系龙潭组和早三叠世夜郎组中，受地层和断层控制。对水银洞矿床的矿物学和地球化学特征进行了详细研究，以探讨其成矿过程。含砷黄铁矿和毒砂是主要的载金矿物。可识别出三种类型的黄铁矿，包括自形和半自形黄铁矿、莓球状黄铁矿和生物碎屑黄铁矿。自形和半自形黄铁矿是主要的载金类型。金在硫化物矿物中以固溶体（Au）和天然纳米级金（Au）的形式存在。硫化物的Co/Ni比值（0.07 - 3.13）表明成矿流体主要受热液活动影响，但不能排除岩浆活动的影响。矿石中的有机质丰富（0.11 - 3.04%），这可能为黄铁矿提供硫，并通过释放有机酸有利于增加围岩的孔隙度和渗透率。稀土元素和微量元素结果表明，还原性岩浆热液流体中含有卤素（F和Cl）。硫同位素数据（-8.64‰至27.17‰）表明硫源复杂，可能是岩浆源、海相硫酸盐还原和细菌硫酸盐还原的组合。硫化物的铅同位素数据表明铅来自地壳和地幔源的混合。在砷的地球化学图中，沿边界断层存在明显的富集带，这意味着砷可能起源于深部地壳，然后随盆地流体迁移到地层中。综合这些结果，可以推断成矿流体是盆地流体和深部源流体的混合物。建立了水银洞金矿床可能的成矿模型。
