Fluid inclusion study on the Duobaoshan porphyry copper deposit, Heilongjiang, China

详细信息   

• 责任者：Wei Ringhai ; Xu ; J. ; Zeng ; Q. ; Liu ; J. ; Chu ; S.
• 年：2012
• 作者单位：University of Science and Technology Beijing, Beijing, China
• 刊：Goldschmidt 2012. Montreal, QC CAN Canada

摘要

The Duobaoshan porphyry Copper deposit, located in Nengjiang county of Heilongjiang province, China, is the largest porphyry deposit in the Central and northern Daxinganling. Ore bodies are hosted in Hercynian granodiorite pluton underlying Ordovician Duobaoshan formation. Hydrothermal alteration in the central core of the ore bodies is dominantly sericitization, from where it grades outward, one side into a poorly mineralizing potassic halo, and the other side into widespread propylitic alteration. Four ore-forming stages are recognized: (I)potassic and silicic stage; (II)silicification-molybdenum stage; (III) phyllic-copper mineralizing stage; and (IV)carbonate-quartz stage. Fluid Inclusions and Isotope Compositions Fluid inclusions are abundant in quartz of various stages. Stage I is characterized by aqueous, and CO (sub 2) -rich inclusions, and stage II is dominated by aqueous, CO (sub 2) -H (sub 2) O, daughter mineral-bearing inclusions. Stage III is also characterized by aqueous and CO (sub 2) -H (sub 2) O inclusions, whereas stage IV is simply aqueous. Homogenization temperatures and salinities for each stage are shown in figure 1. Estimated trapping pressures for stage I, II, III are 110-160 MPa, 58-80 MPa, and 8-17 MPa, corresponding trapping temperatures are 375-650 degrees , 310-350 degrees , 210-290 degrees . The delta D and delta (super 18) O values of fluids range from -82.2 to -101.5 per mil and 2.0 to 8.1 per mil respectivly, which indicates a evolution process from magmtic hydrothermal fluid to a mixing magmtic and meteoric fluid. The delta (super 34) S values of sulfides mainly range from -1.6 to -4.6 per mil, suggesting predominantly source of deep magma chamber. The ore-forming fluid generally belongs to H (sub 2) O-CO (sub 2) -NaCl fluid system, and mixing, immisicibility and boiling action of ore-forming fluid play a significant role for metallic sulfide deposition.