Involvement of anomalously As-Au-rich fluids in the mineralization of the Heilan'gou gold deposit, Jiaodong, China: Evidence from trace element mapping and in-situ sulfur isotope composition

Based on the distinctive textural and compositional signatures between Py-IIa and Py-IIb, it is proposed that anomalously As-Au-rich fluids were injected into hydrothermal systems during the late ore-forming stage, which may have intensively interacted with certain sedimentary rocks. The involvement of these fluids, firstly documented in this study, can largely explain the occurrence of native gold ore shoots at Heilan'gou. In addition, the intimate association between As and Au highlights the important roles of As in enrichment of Au in the Jiaodong gold district.