云南澜沧哈卡玛锑金矿床年代学及成矿作用特征研究OA

The Hakama Sb-Au deposit in Lancang,Yunnan Province,is a newly discovered antimony-gold deposit located within the Changning-Menglian suture zone in the southern segment of the Yunnan-Tibet Sb belt.The deposit has complex structures and its genesis remains poorly understood.In this study,in situ major and trace element and S-Pb isotope analyses were carried out on metal sulfides from the deposit,together with C-O isotope and U-Pb dating analyses on ore-stage calcite.LA-ICP-MS U-Pb dating of ore-stage calcite yielded an Sb mineralization age of 16.6±2.5 Ma,indicating that the deposit formed during the Cenozoic.Trace element analyses reveal a coupled substitution mechanism of 2Sb³⁺ ↔ Cu⁺+Pb²⁺+As³⁺ in stibnite,whereas Sb³⁺ ↔ As³⁺ is dominant in arsenopyrite/pyrite.Gold occurs mainly as isomorphism in defects or vacancies in the pyrite/arsenopyrite lattice caused by the incorporation of As,with minor amounts occurring as microscopic inclusions.The C-O isotopic compositions of ore-stage calcite show δ¹³CV-PDB values ranging from-1.71‰ to 0.72‰ and δ¹⁸OV-SMOW values from 0.01‰ to 7.24‰(n=5),indicating that the ore-forming fluids were mainly derived from magmatic water,with later mixing of meteoric water.The δ³⁴SV-CDT values of metal sulfides range from-4.29‰ to-0.29‰,with an average of-3.25‰(n=20),and the narrow range suggests a predominantly magmatic sulfur source.The Pb isotopic compositions(²⁰⁶Pb/²⁰⁴Pb=19.71～20.47,²⁰⁷Pb/²⁰⁴Pb=15.79～15.85,²⁰⁸Pb/²⁰⁴Pb=38.91～39.00)indicate that the ore-forming materials were mainly derived from the upper crust.Combined with the regional geological setting,it is proposed that the formation of the Hakama deposit was controlled by post-collisional extensional tectonics.Hydrothermal fluids migrated along fault systems and leached ore-forming materials from the country rocks,and eventual mixing with meteoric water in fracture zones triggered ore precipitation and orebody formation.Overall,the Hakama deposit is structurally controlled low-temperature hydrothermal Sb-Au deposit.