Decompression induced enrichment and precipitation of gold in the polymetallic sulfide stage of the northwest Jiaodong gold deposits, eastern North China Craton

Bao，Chuang1,2,3; Chen，Bin1; Liu，Chunjiang4; Zheng，Jiahao1; Liu，Shuaijie1

2022-09-01

10.1016/j.oregeorev.2022.105048

ORE GEOLOGY REVIEWS   Impact Factor & Quartile

0169-1368

1872-7360

Mechanisms for the enrichment and re-precipitation of gold in the giant Jiaodong gold deposits (eastern North China Craton) remain poorly constrained. To better understand the mineralization mechanism, we did in situ analyses of S isotopes on sulfides such as pyrite, pyrrhotite, galena and chalcopyrite from the disseminated (altered-rock type) and quartz-vein type gold deposits by femtosecond laser ablation coupled multi-collector inductively coupled plasma mass spectrometry. Pyrites from the altered-rock type gold deposit show δS values in the range from 7.4 to 11.3 ‰, which is obviously heavier than the quartz-vein type gold deposits with δS = 6.2 ∼ 8.8 ‰. Traditionally, the difference of sulfur isotopic compositions between the two types of gold deposits was attributed to the change in oxygen fugacity. However, we found that, from early to late metallogenic stage, sulfur isotopes of pyrites from the altered rock type gold deposits tend to decrease gradually and pyrrhotites can always be observed in the third stage. Moreover, the S isotopic compositions (δS = 7.9 to 8.2 ‰) of the pyrites coexisting with magnetite are comparable with those (δS = 6.2 to 8.0 ‰) of the pyrites coexisting with pyrrhotite in the quartz vein type gold deposits. These features indicate that the decrease of sulfur isotopes in pyrites was not caused by increase of oxygen fugacity. We suggest that the S isotopic and f variation could be ascribed to an increase of pH of the ore-forming fluid, which is supported by the typically quartz dissolution and common occurrence of calcite and pyrrhotite in the late metallogenic stage (the third stage) and an overall decrease of aluminum contents of quartz from core to rim. We further proposed that the variation of pH of ore-forming fluids is probably related to a process of decompression due to development and enlargement of fractures filled with ore-forming fluids. Gold enrichment in the main ore-forming stage of the northwest Jiaodong gold deposit probably was realized by multiple phases of fluid pressure fluctuation, which subsequently led to repeatedly dissolution and re-precipitation of Au from pyrites due to decreasing oxygen fugacity and increasing pH values of the ore-forming fluids.

Decompression Jiaodong gold deposit Oxygen fugacity pH Sulfur isotope

SCI ; EI

English

First ; Corresponding

Guangdong Ocean University[060302032103];China Postdoctoral Science Foundation[2019M662175];

Geology ; Mineralogy ; Mining & Mineral Processing

Geology ; Mineralogy ; Mining & Mineral Processing

WOS:000862692200002

ELSEVIER

20223112468830

Calcite ; Copper compounds ; Deposits ; Dissolution ; Fluid inclusion ; Gold compounds ; Isotopes ; Laser ablation ; Magnetite ; Mass spectrometry ; Oxygen ; Pyrites ; Quartz ; Sulfur compounds

Minerals:482.2 ; Heavy Metal Mines:504.3 ; Precious Metals:547.1 ; Fluid Flow:631 ; Heat Transfer:641.2 ; Laser Beam Interactions:744.8 ; Chemistry:801 ; Chemical Operations:802.3 ; Chemical Products Generally:804 ; Inorganic Compounds:804.2

GEOSCIENCES

2-s2.0-85135118855

Scopus

1.Southern University of Science and Technology,Department of Earth and Space Sciences,Shenzhen,518055,China
2.Laboratory for Coastal Ocean Variation and Disaster Prediction,College of Ocean and Meteorology,Guangdong Ocean University,Zhanjiang,524088,China
3.Key Laboratory of Climate,Resources and Environment in Continental Shel Sea and Deep Sea of Department of Education of Guangdong Province,Guangdong Ocean University,Zhanjiang,524088,China
4.Zhaojin Ming Industry Company Limited,Zhaoyuan,Canzhuang Gold Mine,265400,China

Bao，Chuang,Chen，Bin,Liu，Chunjiang,et al. Decompression induced enrichment and precipitation of gold in the polymetallic sulfide stage of the northwest Jiaodong gold deposits, eastern North China Craton[J]. ORE GEOLOGY REVIEWS,2022,148.

Bao，Chuang,Chen，Bin,Liu，Chunjiang,Zheng，Jiahao,&Liu，Shuaijie.(2022).Decompression induced enrichment and precipitation of gold in the polymetallic sulfide stage of the northwest Jiaodong gold deposits, eastern North China Craton.ORE GEOLOGY REVIEWS,148.

Bao，Chuang,et al."Decompression induced enrichment and precipitation of gold in the polymetallic sulfide stage of the northwest Jiaodong gold deposits, eastern North China Craton".ORE GEOLOGY REVIEWS 148(2022).