浙赣皖相邻区燕山期花岗质岩类含矿性及其氧逸度特征

Two intense tectonic-magmatic activities during the Yanshanian have been identified in the adjacent area of Zhejiang, Jiangxi, and Anhui provinces (the WZG region). Correspondingly, there are two entirely different kinds of granites. The early Yanshanian granites are composed of granodiorite, and the rock is nearly neutral, enriched in Au, Ag, Cu, Mo, and Ni elements. The late Yanshanian granites are composed of granite porphyry, and the rock is acidic, depleted in these metallogenic elements. Therefore, the Cu, Au, Mo mineralization in the study region is related to these Yanshanian plutons. The oxygen fugacity (f_O2) of the magma calculated by zircon Ce anomalies and Ti-in-zircon temperatures shows that the average magmatic f_O2 for the early Yanshanian granites in the study area is fayalite-magnetite-quartz (FMQ) +2.7, much higher than that of the late Yanshanian granites (FMQ -1.1). Thus, the high oxygen fugacity contributes to the formation of Cu, Au, and Mo deposits. With the popularity of the zircon analysis, it is much easier to obtain the content of rare earth elements in zircon. Using zircon trace element to calculate the oxygen fugacity tends to have a broad prospect.