The relationship of the alteration zonation in the Duobuza porphyry copper-gold deposit with pyrite——The foundation of geophysical method selection and anomaly interpretation

Abstract: The Duobuza porphyry copper deposit was discovered in recent years in Tibet. It is located in the western part of the Bangong Co-Nujiang River metallogenic belt. From the interior to the outer part of this deposit, there exists zoning of potassic alternation, phyllic alteration and propylitization. Potassic alternation is mainly developed in the granodiorite porphyry outcropping area, sericitization is developed surrounding the potassic alteration zone and superimposed upon the potassic alteration zone, and propylitization occurs in lamps on the western side of the deposit. This paper expounds the relationship between the grade tendency line of Cu in the drill hole and the orderly zoning in the Duobuza deposit, and further demonstrates that the potassic alteration zone and the orebody have a close corresponding relationship. Based on the pyrite distribution trend and the actual ore comparative analysis as well as the study of rock geophysical properties the authors reached the preliminary conclusion that the ore-bearing granite diorite porphyry is characterized by high resistivity and polarizability. On such a basis, method test and geochemical data processing were conducted in typical deposits. According to the inferred results and actual orebody position, it is held that the orebody mainly occurs in the high resistivity, high polarizability and magnetic field gradient zone, whereas Cu-As-Sb-Au high background area is located in the shallow part. The results obtained by the authors further improve the method choice and provide the basis for the prognostic work in the Duobuza porphyry deposit.