LIN Kun1, SHI Ze-ming1,2*, ZHU Fei-lin1,2, ZHANG Jun-ji1, ZHANG Kai-liang1, CHENG Ke1
（1. Chengdu University of Technology, Chengdu 610059, China;
2. Sichuan Key Laboratory of Nuclear Techniques in Geosciences, Chengdu 610059, China）
Abstract: The Shannan area is in a volcanic-magmatic tectonic belt on the southern margin of the eastern section of the Gangdise belt. It is a metallogenic belt with great mineral resource potential. This paper has presented the sulfur and lead isotopic data of sulfides from ores of typical deposits in the metallogenic belt, and discussed the source characteristics and metallogenic regularity of the Shannan belt from aspect of the sources of ore-forming materials with the combination of the regional tectonic evolution. The results show that the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of rocks and ores in various deposits vary from 18.34 to 19.03, from 15.54 to 15.86, from 38.31 to 39.66, and from 18.38 to 19.58, from 15.54 to 15.86, from 38.25 to 39.66 respectively, with rich radiogenetic lead and good correlations in the illustration of tectonic environment evolution by lead isotopes, reflecting the consistency of their material sources. Combined with the illustration of tectonic environment evolution by lead isotopes and Δγ-Δβ genetic classification of lead isotopes, data of the ore samples are plotted into a field of the Gangdise granite batholith, indicating that the ore-forming materials were derived from the crust-mantle interaction, with the lead isotope characteristics of the orogenic belt. Lead isotopic compositions of ores show an obviously special and temporal variation regularity as the percentage of crustal materials in the ore-forming materials is gradually increased from the north side to south side of the Yarlung Zangbo River. Meanwhile, the ore-forming materials of early stage have dominant mantle lead while those of late stage have dominant crustal lead, indicating that the ore-forming materials of late hydrothermal stage are mainly derived from crustal sources with minor mantle materials, while the ore-forming sources of early stage may be mainly derived from mantle materials with minor crust materials. The sulfur isotopic compositions have consistent characteristics of the deep magmatic originated sulfur. Moreover, the average δ34S values of ores in the Kelu and Shuangbujiere deposits are obviously lower than those of ores in the Nuri, Chengba, Mingze, and Chongmuda deposits, indicating that the late ore-forming materials of the late stage contain relatively high percentage crustal materials.
Keywords: Shannan area in Tibet; sulfur isotope; lead isotope; ore-forming material source; metallogenic regularity
ACTA MINERALOGICA SINICA Vol. 39, No.1, 2019, page 75-82
