Ore-Forming Fluids Signature and Evolution in the Qiagong Fe Skarn Deposit of the Gangdese Belt, Tibet: Implications for Fe-Pb Mineralization

被引：1
|
作者：
Sun G. [1 ,2 ]
Wu Y. [3 ]
Zheng Y. [1 ,4 ]
Xu J. [4 ]
Li M. [1 ]
Wang Y. [1 ]
机构：
[1] School of Earth Sciences and Resources, China University of Geosciences, Beijing
[2] Beijing Sanyi Intelligent Technology Co. Ltd., Beijing
[3] Central Geological Exploration Fund, Beijing
[4] Faculty of Earth Resources, China University of Geosciences, Wuhan
来源：
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | 2019年 / 44卷 / 09期
关键词：
Fluid inclusion; H-O isotopes; Laser Raman; Ore deposit; Qiagong; Skarn deposit; Tibet;
D O I：
10.3799/dqkx.2018.564
中图分类号：
学科分类号：
摘要：
There is still lack of research on the evolution of ore-forming fluids and ore-forming mechanism of the Qiagong Fe skarn deposit in the Gangdese Belt, especially the mineralization of the iron-lead ore body. We studied the homogenization temperature, salinity, laser Raman spectroscopy and H-O isotopic compositions of major minerals in different stages. The homogeneous temperatures of the fluid inclusions that in the prograde stage range from 400 to 550 ℃, and the salinities vary from 15.5% to 20.95% NaCleqv. Besides, the salinity of S-type fluid inclusion in this stage is up to 56.5% NaCleqv. Both the vapor and the liquid phases in these fluid inclusions are H2O. The homogeneous temperatures of fluid inclusions during the retrograde stage range from 350 ℃ to 420 ℃, and the salinities are primarily concentrated in 14.1%-16.68% NaCleqv, partly in 2%-8% NaCleqv. However, the salinity of type-S inclusion is up to 55.8% NaCleqv. Both the vapor and the liquid phases in these fluid inclusions are H2O. In addition, the liquid phase is also rich in HCO3 - and CO3 2-. The homogeneous temperatures of the fluid inclusions in quartz-galena stage are 238-343 ℃, corresponding to the salinities of 3.1%-13.9% NaCleqv. Additionally, the total homogenization temperatures of CO2-bearing three-phase fluid inclusions are 290-310 ℃, corresponding to the salinities of 1.6%-11.2% NaCleqv. Lastly, during the quartz-calcite stage, the homogeneous temperatures and salinities of the fluid inclusions vary in 242-360 ℃ and 1.7%-11.8% NaCleqv respectively. The component of liquid phase in fluid inclusion is dominated by H2O, as well as the vapor phase. The H-O isotopes show that the δDH2O and δ18OH2O are -106.4‰--113.2‰ and 6.2‰-8.0‰ during the prograde stage, and -84.8‰--130.1‰ and 2.7‰-5.5‰ during the retrograde stage, respectively. The δ18OH2O compositions in the retrograde stage are lower than those in the prograde stage. The δDH2O and δ18OH2O are -95.3‰--103.8‰ and -1.6‰- -0.7‰ in the quartz-galena stage and -67.4‰--101.0‰ and -0.8‰-0.6‰ in the quartz-calcite stage, respectively. These data indicate that the fluids evolved from high temperature, medium-high salinity to low temperature and low salinity. The ore-forming fluids are mainly derived from magma exsolution in skarn stage. The fluid immiscibility and wall-rock interaction during skarn stage are the main mechanisms of magnetite precipitation. Decreased pressure and temperature during quartz-galena stage might be the prime reasons for precipitation of galena. © 2019, Editorial Department of Earth Science. All right reserved.
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页码：3007 / 3025
页数：18
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