引用本文：刘函,李俊,崔浩杰,苟正彬,李奋其,张士贞,段瑶瑶.2020.尼雄地区早白垩世磁铁矿伸展成矿地质背景及成矿模型[J].地质学报,94(8):2383-2399. LIU Han,LI Jun,CUI Haojie,GOU Zhengbin,LI Fenqi,ZHANG Shizhen,DUAN Yaoyao.2020.Metallogenic background and metallogenic model of the Early Cretaceous magnetite deposit in the Nixiong area, Tibet[J].Acta Geologica Sinica,94(8):2383-2399.
Abstract:The Nixiong Iron Mine, a large magnetite deposit in the central Gangdese belt, was mainly formed in the Early Cretaceous. This paper will discuss the metallogenic background of Early Cretaceous Nixiong magnetite deposit that can be divided into the Skarn type and the hydrothermal vein type. Gabbro dyke in mining area yielded the U Pb age of 120. 1±1. 7 Ma which limits the mineralization era of the hydrothermal vein magnetite to about 120 Ma and is fully consistent with the determined mineralization era of Skarn magnetite deposit, indicating that a similar tectonic setting controlled both types magnetite deposits. Clastic rocks, as the wall rock of the Nixionggranitoid from the Upper Permian Dibucuo Formation, yielded a detrital zircon U Pb age of 130~120 Ma with the youngest peak age of 131.25 Ma which was prior to the emplacement age of the Nixiong rock (~120 Ma) suggesting that the Upper Permian Dibucuo Formation should be renamed to be the Lower Cretaceous. Combined with the new regional stratigraphic and magmatic data, we propose that an Early Cretaceous volcanic intrusive complex system consisted of volcanic rocks from the Zenong Group and emplacing granitoid in the Zenong Group in the Central Gangdese belt. This Early Cretaceous metallogenic magmatic system is closely related to the Early Cretaceous Nixiong magnetite deposit. Both geochemical characteristics of the Early Cretaceous igneous rocks and the shallow surface structure show an extensional tectonic setting in the Central Gangdese belt in the Early Cretaceous. Based on the new understanding of the tectonic background in Nixiong area, a metallogenic geological model of the Early Cretaceous Nixiong magnetite deposit was established.