The Relationship between the Evaporate and Skarn-Type Iron Deposit: A Case Study of the Jinshandian Iron Skarn Deposit in Hubei Province
详细信息
- 责任者：Zhu Qiaoqiao (Institute of Mineral Resources ; CAGS ; Beijing 100037 ; China) ; Xie Guiqing
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(9)
- 关键词：膏盐层 ; gypsum and salt succession ; 铁矿 ; iron ores ; 湖北 ; Hubei Province
- 页码：p.1419-1429
- 图表：8 illus., 2 tables, 58 refs.
- 分类号：1001
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
Evaporate,composed dominantly of varying proportions of halite,anhydrite and gypsum,has showed strong relationship with the ore-forming process,especially the magmatic-hydrothermal related deposit,but its detailed effect has not been studied.The Jinshandian iron skarn deposit has distinct minerals assemblages such as anhydrite,gypsum,pyrite and scapolite,which were resourced from evaporate.The ranges of δ34S values for evaporate related minerals are+16.2‰+19.4‰for pyrite（n=9）,+24.9‰ +27.9‰for anhydrite（n=10）and+27.5‰+28.4‰（n=2）for gypsum.The latter two are close to the values of the strata of the Middle Triassic Series at the Middle Low Yangze River,suggesting that the evaporate has offered sulfur for the ore-forming system.Sulfate-sulfide mineral fractionation is consistent with an approach to isotopic equilibrium,and calculated temperatures for coexisting anhydrite-pyrite pairs（n=6）are 563728℃,which is much more higher than the temperatures gotten from fluid inclusions.Existing data show that evaporate has joined in the ore-forming system at the stage of high temperate magmatic-hydrothermal or maybe more earlier.Cl content in scapolite is as high as 4%,indicated NaCl equiv（%）of the fluid could have reached 70%.Dissolution of evaporate has the effect of increasing the salinity of the fluid,which enhanced the capacity of leaching and transporting iron and the solubility of anhydrite.With a large amount of anhydrite joining in the ore-forming system,the oxidation state of the system were changed obviously,which provided advantageous condition for the formation of magnetite ores.