| Abstract: | The Shibangou gold deposit in western Henan is associated with irregular quartz veinlets occurring in altered shear zones dissecting a dioritic intrusion. The altered shear zones are characterized by silicification, pyriti-zation, sericitization, chloritization and K-feldspar alteration. Zoning of altered rocks adjacent to the Au-bearing quartz veins is obviously exhibited. Fine-grained sulphides and quartz veinlets of different ages and small-scale fissures are widely distributed in the central part of the altered zones. Major mineralization types in this gold deposit are Au-bearing quartz vehlets and altered rocks in the shear zones. Samples were collected from drilling cores according to the alteration zoning and mineralization type and all samples were analyzed for major and trace elements. Mass balance, volume change (fv=97.3-71.9%) and major element variation sequences are studied in terms of major elements. The changes of mobile components (SiO2, K.2O, Fe2O3 and CaO) and immobile component (Al2O3) in the wall-rock alteration are discussed. The gold mineralization is associated with the enrichment of As, Ag, Hg and Pb and depletion of Cu and Zn. The study of compositional variation of altered rocks proves to be a very efficient method for defining the extent of wall-rock alteration, fluid activity and mineralization and enrichment. |
