地质学报2018，Vol.92Issue(5)：1041-1055,15.
膏盐层在云南会泽和毛坪铅锌矿成矿中的作用:硫同位素证据
Effect of Sulfate Evaporate Salt Layer in Mineralization of the Huize and Maoping Lead-Zinc Deposits in Yunnan: Evidence from Sulfur Isotope
摘要
Abstract
The Huize and Maoping deposits,the famous high-grade Mississippi Valley-type lead-zinc deposits in China,are located in the central south of the Sichuan-Yunnan-Guizhou lead-zinc polymetallic ore cluster area in the southwestern margin of the Yangtze block and tectonically in structural composite area of Xiaojiang fault zone,Zhaotong-Qujing hidden fault zone,and Yadu-Ziyun fault zone.This study discussed effect of sulfate evaporate salt layer on lead-zinc mineralization of the Huize and Maoping deposits using sulfur isotope compositions of sulfides and gypsum from the two deposits.δ34 SV-CDT value of the Huize ore sulfides ranges from 11.0‰ to 20.0‰ (averaging 14.7‰),with most concentrated in 13.0‰～17.0‰,roughly representing total sulfur isotopic composition.δ34 SV-CDT value of the carbonate-associated sulfate ranges from 10.4‰ to 18.6‰ (averaging 13.1‰),slightly lower than the ore sulfides.δ34 SV-CDT value of the gypsum in the Carboniferous gypsum salt layer ranges from 12.9‰ to 17.1‰ (averaging 13.6‰),which is consistent with that of the carbonate-associated sulfate.δ34 SV-CDT value of the ore sulfides in the Maoping deposit is closely related to its occurrence layers.The δ34 SV-CDT value of the ore sulfides in the Baizuo Formation (C1b) ranges from 7.1‰ to 17.5‰,with an average of 12.8‰,which is slightly lower than carbonate-associated sulfate and gypsum in Carboniferous carbonate strata.The δ34SV-CDT value of ore sulfides in the Zaige Formation (D3zg) ranges from 18.3‰ to 22.7‰,with an average of 21.1‰.The results are unlikely with the ore sulfides in the Baizuo Formation (C1b) or the Huize deposit.The δ34 SV-CDT value of the gypsum in the Zaige Formation (D3zg) ranges from 21.9‰ to 25.9‰,with an average of 23.6‰,which is slightly higher than sulfides in the Zaige Formation (D3zg).By comparing the sulfur isotopic compositions of the sulfides,sulfate and gypsum,we propose that the sulfur in the ore sulfides of Huize and Maoping lead-zinc deposits mainly came from the sulfate in the ore-bearing strata.In addition,sulfur in the ore sulfides of the Huize lead-zinc deposit mainly came from Carboniferous gypsum salt layer,with only 10％ of the sulfur from the underlying Zaige Formation gypsum salt layer;while sulfur in the Zaige Formation ore sulfides of Maoping lead-zinc deposit derived from the Zaige Formation gypsum salt layer,sulfur in the Baizuo Formation ore body mainly came from the Baizuo Formation gypsum salt layer,i.e.the gypsum was reduced in situ.Collectively,we divided the metallogenic process into two stages.At the first stage,gypsum reacted with methane and/or other organic compositions forming hydrogen sulfide gas,which preserved in interlayer fissures or karst caves companied with large scale dolomization.At the second stage,ore-forming fluids containing Pb,Zn and other metals leached from the basement rocks mixed with H2 S-rich fluids,resulting in precipitation of pyrite,galena,sphalerite and forming high-grade ores,关键词
会泽超大型铅锌矿床/毛坪铅锌矿床/硫同位素/膏盐层Key words
Huize lead-zinc deposit/Maoping lead-zinc deposit/sulfur isotope/sulfate evaporate salt layer引用本文复制引用
任顺利,李延河,曾普胜,邱文龙,范昌福,胡古月..膏盐层在云南会泽和毛坪铅锌矿成矿中的作用:硫同位素证据[J].地质学报,2018,92(5):1041-1055,15.基金项目
本文为国家自然科学基金项目(编号41473014)资助成果. （编号41473014）
