Genetic Mineralogy and Prospecting Mineralogy of the Dulanggou Gold Deposit in Danba, Sichuan Province

Dulanggou gold deposit in Danba, Sichuan, located on the western margin of the Yangtze Block, it is a large-scale gold deposit discovered in the Daduhe gold metallogenic belt in recent years. Distinguishing from typical orogenic gold deposits, the primary gold-bearing minerals in Dulanggou gold deposit are tellurium-bismuth minerals, which are relatively unique within the metallogenic belt and of great research value. To precisely determine the genetic type of Dulanggou gold deposit and clarify the exploration direction in its depth and periphery, this paper, from the perspectives of genetic mineralogy and indicator mineralogy, conducted micro-compositional analyses of pyrite, pyrrhotite, and sphalerite in Dulanggou gold deposit using Electron Probe Micro-Analyzer (EPMA) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). Additionally, second-order cluster analysis was applied to investigate the indicator mineral signatures of pyrite and pyrrhotite. The test results show that the content ranges of Ni and Se in pyrite are 0×10^–6 to 991.72×10^–6 and 32.42×10^–6 to 131.02×10^–6, with an average of 326.06×10^–6 and 77.74×10^–6, respectively; Ni in pyrrhotite is 13.90×10^–6 to 647.62×10^–6, with an average of 324.02×10^–6; and in sphalerite, the average content of Fe and Zn are 8.77% and 54.24%. The geochemical characteristics of pyrite and sphalerite suggest that the Duolangou gold deposit is a hydrothermal-type deposit. The mineral thermometer indicates that the Duolangou gold deposit formed at a relatively high temperature, classifying it as a medium- to high-temperature deposit. The fluid logfS₂ values during the main mineralization stage range from −11.6 to −4.5, while the logfTe₂ values range from −13.0 to −7.9. Both magnetite and pyrite formed during the quartz-sericite-magnetite stage; however, the Ni content in magnetite and pyrite varies significantly. The deep-source magmatic hydrothermal fluids during the main mineralization stage likely contributed to the increased Ni content in some magnetite and pyrite. Therefore, pyrite and magnetite can be considered indicator minerals for the Duolangou gold deposit.