The Role of Halosalt in Mineralization of the Jinding Pb-Zn Deposit: Evidence from Sulfur and Strontium Isotopic Compositions
详细信息
- 责任者：Hu Guyue (Key Laboratory of Metallogeny and Mineral Assessment ; MLR ; Institute of Mineral Resources ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Li Yanhe
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(11)
- 关键词：铅锌矿床 ; lead-zinc deposit ; 云南 ; Yunnan Province
- 页码：p.1694-1702
- 图表：4 illus., 1 table, 56 refs.
- 分类号：1001
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
The Yunnan Jinding Pb-Zn,celestite,anhydrite and pyrite super-large composite deposit is located at the northern part of Lanpin basin,which is also rich in organic materials such as bitumen and heavy oil.Theδ34SV-CDT values of anhydrite and gypsum are mostly concentrated around+12‰~+16‰,similar to the Triassic marine sulfate(+15‰).Theδ34SV-CDT values of celestite distribute around that of anhydrite,withδ34SV-CDT values of+6~+26‰.Except less amount of sulphates that have relative lower biogeneticδ34SV-CDT values during the primary diagenesis and mineralization stage,most of metallic sulfides present a distribution characteristic of"two-group",one group ofδ34 SV-CDT values is concentrated at-12‰ ~-20‰,about 30‰ lower than theδ34 SV-CDT values of anhydrite;another group ofδ34 SV-CDT values is concentrated at-8‰ ~-2‰,about 20‰ lower than theδ34 SV-CDT values of anhydrite.When the temperature of the main mineralization stage is around 200℃,the sulfur isotopic exchange level between aqueous sulfates and sulfides is 30‰,while the sulfur isotopic exchange level reaches to 20‰ at 300℃.This phenomenon is consistent with the"two-group"distribution characteristic of the Jinding deposit,demonstrating that most of sulfur element involved in the deposit derived mainly from thermochemical sulphate reduction of organic matters in Triassic halosalt minerals.When the ore-forming fluids containing cations such as Pb2+,Zn2+and Sr2+converge hydrothermal solution with organic matters,CO2,H2S and sulphate in the nappe dome structure,galenite and sphalerite are formed due to reaction of Pb2+,Zn2+with H2S,and celestite is ormed due to reaction of Sr2+with SO2-4.In addition,the Sr isotope values(87Sr/86Sr=0.707765~0.710553)of celestite,anhydrite,brecciated limestone and metal sulfides indicate that Sr in the halosalt ore deposits might not only derive from the Triassic marine stratum(87Sr/86 Sr=0.70695~0.70845)but also extract from multiple strata or evaporate through which ore-forming fluids pass.Due to contamination from the high ratio of strontium isotope in ore-forming fluids,the strontium isotope level in brecciated limestones and metallic sulfides are significantly increased.The combination of halosalt minerals-organic matters(or oil gas)-metal sulfides may be a universal law in economic geology.