Fluid immiscibility and gold deposition in the Xincheng deposit, Jiaodong Peninsula, China: A fluid inclusion study

• DOI: 10.1016/j.oregeorev.2014.06.006
• Publication Date: 2014-06-11T19:48:19Z
• Authors: Zhong-Liang Wang; Li-Qiang Yang; Lin-Nan Guo; Erin Marsh; Jian-Ping Wang; Yue Liu; Chao Zhang; Rui-Hong Li; Liang Zhang; Xiao-Li Zheng; Rong-Xin Zhao
• Keywords: Stockwork; Sericite; Breccia; Paragenesis; Mesothermal

The Xincheng gold deposit, located in west Jiaodong Peninsula southeast North China Craton, is a representative mesothermal lode deposit hosted Late Mesozoic granitoids Jiaodong. Gold mineralization occurs as disseminated- and stockwork-style ores within the hydrothermal breccias cataclastic zones controlled by Jiaojia fault, whereas echelon tensile auriferous veins NE- NNE-trending subsidiary faults cutting occur subordinately. According to crosscutting relationships mineral paragenesis, four paragenetic stages were identified, which are pyrite–quartz–sericite (stage 1), quartz–pyrite 2), quartz–polysulfide 3) quartz–carbonate 4). was deposited during stages. On basis of microthermometry Raman spectroscopy on fluid inclusions contained quartz from 2 3, three types recognized: (1) type 1 H2O–CO2 that show high temperatures (ca. 260 °C), low salinities (2.4–8.9 wt.% equiv. NaCl) variable XCO2 (0.03 0.20), (2) aqueous with medium 220 °C) moderate (3.1–13.3 NaCl); (3) 3 pure CO2 carbonic phase density 0.712 ± 0.03 g/cm3. Types appear same growth grains veins. These coexisting likely formed immiscibility due unmixing single homogeneous parent at trapping P–T conditions 221 304 °C (average 261 19 780 2080 bar. interpreted be initiated pressure decrease ca. 300 °C. ore-fluid P–T–X those for deposits. most probably transported Au(HS)2− complex Xincheng. Fluid over temperature interval 221–304 resulted significant H2S loss solution, thereby reducing solubility concomitant deposition gold. mineralizing process granitoid-hosted lode-gold related immiscibility.