Ore genesis of Badi copper deposit, northwest Yunnan Province, China: evidence from geology, fluid inclusions, and sulfur, hydrogen and oxygen isotopes

• Published in: Acta geochimica 2018-08, Vol.37 (4), p.559-570
• Main Authors: Yin, Hejun, Huang, Jianguo, Ren, Tao
• Format: Article
• Language: English
• Subjects: Analytical methods; Bearing; Boiling; Carbon dioxide; Chalcopyrite; Chemical analysis; Copper; Copper ores; Earth and Environmental Science; Earth Sciences; Fluid inclusions; Fluids; Forming; Fugacity; Geochemistry; Geology; High temperature; Hydrogen; Isotopes; Low temperature; Meteoric water; Original Article; Oxygen; Oxygen isotopes; Provinces; Quartz; Raman spectroscopy; Salinity; Salinity effects; Seawater; Spectroscopy; Sulfides; Sulfur; Sulphides; Sulphur; Temperature; Temperature effects; Water analysis
• ISSN: 2096-0956; 2365-7499
• DOI: 10.1007/s11631-017-0252-5

The Badi copper deposit is located in Shangjiang town, Shangri-La County, Yunnan Province. Tectonically, it belongs to the Sanjiang Block. Vapor–liquid two-phase fluid inclusions, CO 2 -bearing fluid inclusions, and daughter-bearing inclusions were identified in sulfide-rich quartz veins. Microthermometric and Raman spectroscopy studies revealed their types of ore-forming fluids: (1) low-temperature, low-salinity fluid; (2) medium-temperature, low salinity CO 2 -bearing; and (3) high-temperature, Fe-rich, high sulfur fugacity. The δ 18 O values of chalcopyrite-bearing quartz ranged from 4.96‰ to 5.86‰, with an average of 5.40‰. The δD values of ore-forming fluid in equilibrium with the sulfide-bearing quartz were from − 87‰ to − 107‰, with an average of − 97.86‰. These isotopic features indicate that the ore-forming fluid is a mixing fluid between magmatic fluid and meteoric water. The δ 34 S values of chalcopyrite ranged from 13.3‰ to 15.5‰, with an average of 14.3‰. Sulfur isotope values suggest that the sulfur in the deposit most likely derived from seawater. Various fluid inclusions coexisted in the samples; similar homogenization temperature to different phases suggests that the Badi fluid inclusions might have been captured under a boiling system. Fluid boiling caused by fault activity could be the main reason for the mineral precipitation in the Badi deposit.