Based on the geological characteristics of Gongpoquan porphyry copper deposit, the metallogenic mechanism is discussed from the aspects of metallogenic material source and copper enrichment etc. Some new ideas are obtained.
Stable isotope analysis shows that δD value of fluid inclusions in mineralized quartz veinlet ranges from-75‰ to-56‰,δ~(18)O_(H_2O)value ranges from 3.7‰ to 12.2‰,and δ~(34)S value of pyrite and stibnite ranges from-2.2‰ to-0.7‰,indicating that metallogenic materials and ore fluid are mainly from the magmatic events.
During the process of talcization, serpentinization and carbonation of the ultrabasic rockbody, the gold and other metallogenic materials join metallogenic solution as sulfur complex under the conditions of alkalis and relative reduction, and deposit under the conditions of the changes of physical and chemical parameters, such as fO2, fS_2, pH, Eh, T, P, etc.
Basing on the isotopic geochemical data in Zhejiang-Jiangxi area uranium deposits in volcanic rocks, analyzing the sources of mineralizing material and mineralizing solution, the authors suggest that mineralizing solution was composed of meteoric water and magmatic water, and mineralizing material was mainly supplied by volcanic rocks and stratum, the mixed proportion of mineralizing solution in different deposits is different, and the source of mineralizing material in different deposits is almost same.
Taking the Dongguashan deposit as a study case, this study invesitigates the mineralizing material origin and metallogenic mechanism of these sedimentary-hydrothermal diplogenetic stratabound copper deposits based on the analysis of isotope geochemistry.
Study on metallogenetic backgrounds,geology of ore deposit,sulphur isotopes and fluid inclusions of main minerals shows that the metallogenetic materials came from the deep crust and mineralization fluids might be hot brine.
Based on systematical study of geological settings and geochemical features of copper deposits, the authors propose that metallogenetic materials of the porphyry-type and hydrothermal vein-type copper deposits in northeastern Hunan Province were mainly from the ore-bearing fluids derived from the granite-porphyry or related dikes through deep magmatic differentiation and partly derived from the wallrocks by extraction during transport and emplacement of granite-porphyry or dikes when the ground water was heated and circulation around the country rocks.