Elements migration during hydrothermal alteration and its indicative significance for mineralization in the Xiayingfang gold deposit， eastern Hebei Province

Xiayingfang gold deposit is a typical magmatic hydrothermal mineralization system, which is located in the eastern section of Yanshan orogenic belt on the margin of North China platform.The alteration halo of sericite in the Lower Jinbaogou ore section is chosen as the research object.The geochemical characteristics of rocks show that different surrounding rock conditions and alteration intensity have certain influence on the activity of elements.The trend of alkali-rich depletion in different rock structures is the same, but the degree of alkali-rich depletion is different, which indicates that the rock structure also has a certain influence on the degree of alteration.With the metasomatic alteration of the magmatic hydrothermal fluid, the pH of the fluid changes from alkaline to acidic, accompanied by a gradual decrease in temperature.Alkaline fluid activates and transfers ore-forming elements Au, Cu, Pb and Zn to acidic medium for precipitation and enrichment. Therefore, pyrite sericitization is the main period of gold unloading in Xiyingfang gold deposit, which can be used as an important indicator for gold prospecting.