摘要
The Matou porphyry Mo-Cu deposit of Anhui province is a typical porphyry ore deposit in the metallogenic belt of the Middle-Lower Reaches of Yangtze River. The mineralization can be classified spatially into three distinct types of alterations: potassic, phyllic and propylitic. This paper investigated the migration regularity of major elements and the characteristic of REE for three different alteration zones. ①The major elements migrated obviously from potassication belt and sericitization belt into propylitization belt. Introduction of K2O, CaO, SiO2, TiO2 and H2O+ suggests that the liquids contained abundant K2O, CaO etc, and distinct loss of Na2O, FeO and MnO implies that mineralization led to major components as Na2O and FeO move away from the ore body, with distinct loss of Na2O, especially Na2O shows negative relation with Mo and Cu. ②The REE curves assume a rightly dipping REE pattern, the enrichment of LREE and the losses of HREE. The mass migration calculation for REE demonstrates the fractionation of REE occurred in the process of mineralized alteration and REEs were increasing gradually from potassication zone to propylitization zone. ③The REE distribution patterns of the samples show that the fresh granodiorite porphyry has the similar curve as altered country rocks, indicating that ore-forming material derived mainly from granodiorite melt, ahd probably with seawater involved. Based on the values of δEu and δCe, and the ratio relation between Fe2O3 and FeO, it can be concluded that the oxygen fugacity was gradually increasing in porphyry fluid and the mineralization environment evolved to an oxidation environment from relatively reduction environment. ④ Except for immobile Al2O3 and TiO2, major elements and REEs migrated in various degree during mineralized alteration. The characteristics of enrichment and depletion and migration regularity are very different.