Re-Os dating of Molybdenite of the Dongmen Cu-Mo ore area in Xinyu, Jiangxi province and its metallogenic significance

Recently, a lot of Cu-Mo mineralization was discovered in the Dongmen serpentine ore area in Xinyu, Jiangxi province.Based on the systemic field survey and identifying the thin sections, lithologic analysis and molybdenite Re-Os dating were carried out to clarify the characteristics of the mineralization and metallogenesis in this paper.It shows that strong skarn alteration has occurred along the contact zone between the Dongmen granodiorite stock and the carbonate Huanglong formation.The major skarn minerals are garnet, diopside, serpentine, wollastonite, calcite and quartz accompanied by a certain amount of metal minerals such as molybdenite, magnetite,chalcopyrite and pyrite.Molybdenite Re-Os dating yielded model ages ranging from 166.9±3.2-167.7±3.2 Ma, with a well-constrained ¹⁸⁷Re-¹⁸⁷Os isochron age of 168.1±2.8 Ma(MSWD=0.23).It shows that the Cu-Mo mineralization related to the Dongmen granodiorite formed at middle Jurassic and is the product of magmatic and metallogenic events triggered in the transition environment from the eastern Tethyan tectonic domain to the Pacific tectonic domain during the early to middle Jurassic.There are ore-prospecting potential of Yanshanian skarn-type of Cu-Mo mineralization in Xinyu, Jiangxi province.