Study On The Mesozoic Metallogenic Associations And Regularities Of The East Qinling, China

Based on the study of the regional geologic setting and the main Mesozoicmetallogenic types of the East Qinling, this paper studies the mineralization ages and thegeochemistry on the newly discovered typical deposits such as Donggou Mo deposit,Shagou Ag-Pb-Zn deposit, Yindonggou Ag-Pb-Zn deposit and Qiushuwan Cu-Mo deposit.Moreover, this paper summarizes the features of the Mesozoic metallic metallogenicassociations and spatiotemporal distribution regularities, and discusses the Mesozoictectonic evolution and mineralization of the area.The Mesozoic deposit types and metallogenic associations of the East Qinling orogenyare reclassified. According to the Mesozoic mineralizing events, this paper puts forwardthree deposit associations of the area: Mantle fluid-related Mo deposit associations formedat ca. 220 Ma;I-type porphyritic intrusions-related Mo-W-Cu-polymetallic metallogenicassociations formed at ca. 140 Ma;Porphyry-related Mo deposits, epithermal gold depositsand structurally controlled Au-Ag-Pb-Zn associations formed at 130 Ma to 110 Ma.Some significant data are obtained through the study on the typical deposits: 1) the146 Ma mean model age and 147 Ma isochron age of the molybdenites from theQiushuwan Cu-Mo deposit is the first reliable age of the mineralization of the NorthQinling orogeny, which is coincident to the second large-scale mineralization pulse of theNorth China and the Lower Yangtze Reach;2) the 112 Ma of the porphyry and the 116 Maof the molybdenites of the Donggou Mo deposit indicates that the deposit formed at thethird mineralization pulse of the East China when the lithosphere thinning occurred;3) the134.5 Ma age of the Shagou Ag-Pb-Zn deposit, similar to that of the related Haopinggouporphyry(133Ma) and Huashan batholith(130.7Ma), implies that they are the products ofthe same magmatic-mineralizing event;4) the geochemistry of the Yindonggou Ag-Pb-Zndeposit exhibits its host rock ore-forming substance derivation. Meantime, the ore bearingfluid in the early stage shows its magmatic derivation and some mixture of magmatic andmeteoric water in the later stage.