吉林长安堡钼铜矿床含矿岩体锆石 U－Pb 年龄和 Hf同位素组成

摘要

Chang'anpu Mo-Cu deposit is a large-scale porphyry deposit newly discovered in central Jilin Prov-ince.The mineralization of copper and molybdenum is closely related to monzogranite.On the basis of research on de-posit geological features,the paper conducted a study of LA-ICP-MS zircon U-Pb dating combined with a Hf iso-tope analysis.The analysis results show that the zircon U-Pb ages of the monzogranite is 170.2 Ma ±0.6 Ma,which is consistent with the previous molybdenite Re-Os weighted mean age (168.0 Ma ±1.0 Ma) within error.It is indi-cated that the Chang'anpu Mo-Cu deposit was formed in the Middle Jurassic.TheεHf ( t) value of the zircon is 7.0 to 10.08.The Hf single and two stage mode ages are 417 Ma to 542 Ma and 570 Ma to 768 Ma respectively.These data imply that the monzogranite in the mineralization zone originated from the growing juvenile crust in the depleted mantle in Neoproterozoic.Considering the regional tectonic background,the paper thinks that the magmatism and mineraliza-tion are probably related to subduction of the paleo-Pacific Plate.%长安堡斑岩型钼铜矿床是吉林中部地区新发现的一座大型矿床，钼铜矿化与二长花岗岩密切相关。在矿床地质特征研究的基础上，对含矿二长花岗岩开展了锆石 LA－ICP－MS U－Pb年代学和Hf同位素研究，获得了二长花岗岩成岩年龄为170．2 Ma ±0．6 Ma，与已获得的辉钼矿Re－Os加权平均年龄（168．0 Ma ±1．0 Ma）在误差范围内基本一致，表明长安堡钼铜矿床成岩成矿作用发生于中侏罗世。锆石εHf（t）值为7．0～10．08，Hf单阶段模式年龄（tDM1）为417～542 Ma，二阶段模式年龄（tDM2）为570～768 Ma，揭示矿区二长花岗岩源自新元古代亏损地幔中增生的新生地壳。成岩成矿作用与古太平洋板块俯冲作用相关。