SHI De-feng1, LI Gui-xian2*, ZHU Yun2, YAN Qing2, LIU Jian-ping3，SUN Lin1

(1. School of Earth Sciences and Spatial Information Engineering, Hunan University of Science and Technology, Xiangtan 411201, China; 

2. The Tenth Geological Brigade of Jiangxi Geological Bureau, Yingtan 335000, China; 

3. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring of Ministry of Education, Central South University, Changsha 410083, China)

Abstract: The Yongping copper deposit, located in the eastern part of the Qinhang metallogenic belt, is an important large-scale Wu-Mo-Cu polymetallic deposit in Jiangxi Province. The lack of detailed studies of elemental geochemistry on this deposit has severely limited the understanding of its ore genetic type and metallogenic process. In this paper, the LA-ICP-MS in situ analytical technique was used to analyze trace element compositions of sphalerites vastly existed in the ore body, in order to provid new data and constraints for the ore genetic study of the Yongping copper deposit. The results show that the sphalerite in the Yongping copper deposit was relatively enriched in Fe, Mn, Cu and Cd, followed by In, Co，Ni and Ga, with the relatively low contents of Ag, Se, Ni, Pb, Bi and Te. Especially, Fe, Cd, Mn, In, Ag, and Ni occurred mainly in the form of isomorphism in the sphalerite, while Cu, Pb and Bi occurred in two forms of isomorphism and particulate inclusion in the sphalerite. The values of Cd/Fe (0.033-0.20), Cd/Mn (0.62-4.15) and Zn/Cd (mostly less than 250) of sphalerites reveal that the mineralization process was closely related to granite magma. The Fe contents (1.1%-9.4%) and values of Ga/Ge (2.0-340.6), Ga/In (0.01-7.00), and Zn/Cd (135.5－318) all indicate that sphalerites were formed under medium temperature mineralization conditions (about 208-289 ℃). Compared with many deposits in China, the trace element contents of sphalerites in the Yongping copper deposit are relatively concentrated, which are obviously different from tose of the MVT-type deposits. The contents of Fe and Cd of sphalerites in the Yongping deposit are significantly lower than those of the typical SEDEX-type and VMS-type deposits, and the compositions of Fe, Mn, Ag, Co, Sb and other elements of sphalerites in the deposit are highly consistent with those of the skarn-type deposits. It is believed that the Yongping copper deposit belongs to the skarn-type deposit, two types of ores with obviously different Fe contents in sphalerites should be respectively formed in the early and late stages of the quartz-sulfide mineralization period. 

Keywords: sphalerite; trace elements; LA-ICP-MS; mineralization conditions; ore genesis; the Yongping copper deposit

ACTA MINERALOGICA SINICA Vol. 43, No. 5, 2023, Page 653