Studies On Fluid Characteristics And Mineralization Mechanism Of The Dabaiyang Gold Deposit, Northwest Of Hebei

Dabaiyang Gold Deposit is located in Chongli terrain Northwest of Hebei the second group of Archean terrain high-grade metamorphic rock series. The main structure is NNW-SSE trending Hanjiagou anticlinorium, and the thrust fault structure provided access for the mineralizing fluid. Then the thrust faults inverted normal faults which were host structures of the Dabaiyang Gold Deposit.By observing the rock characteristics of Xiangshuigou granite, propose that the hydrothermal activities are K-rich residual meltsâ†'wide quartz vein with pyriteâ†'quartz vein with metal sulfideâ†'epidote vein. Geochemical characteristics indicate that the Xiangshuigou granite belongs to alkaline granite which has lower gold element. The Xiangshuigou granite not the main gold ore of Dabaiyang Gold Deposit, can provide the limited amount of gold resources. However, Xiangshuigou granite which includes pro-poor iron elements, abundant pro-sulfur elements,heat and a part of mineralizing fluid by Magmatic emplacement is necessary for mineralization.Zircon U-Pb dating ages of the Xiangshuigou granite.Combined with tectonic setting in the Zhangxuan area.Yield, the paper inferred that the main mineralized period is at the later variscian period.Through the fluid inclusions microthermometry, Laser Raman microprobe and analysis of fluid inclusions groups, Dabaiyang Gold Deposit’s ore-forming fluid is the NaCl-H20 system fluid, which is the Na-K-SO4-Cl type of protosalt weak base-weak acid in high-temperature hydrothermal solutions. By the hydrogen-oxygen isotope, the Dabaiyang Gold Deposit’s epithermal is a multi-source mixing hydrothermal, and the main component is the atmospheric water. From the early to late mineralization, more and more atmospheric water pours into the hydrothermal mineralization, precipitation of gold has played an important role.The sulphur of the Dabaiyang Gold Deposit mainly comes from the Archean terrain mesometamorphic rock series. However, by varieties of geological effects in the later, the sulphur isotope shows obvious "lightweight." The original lead mainly comes from the lower lithosphere. By the influence of multi-period geological effect, the lead was brought into the orogenic belt in Variscian period, and then mixed with a little amount of lead in the mantle.When temperature and pressure suddenly change, the gold fluid of the Dabaiyang Gold Deposit fluid mainly moves in the form of the Au-S and Au-Cl complex. When temperature and pressure suddenly change, a large number of the magma volatile component because of supersaturation escape, and then mixed with groundwater form a gas- water hydrothermal fluid balance system. Such as Au, Pb, Cu and the other ore-forming elements into the fluid, the formation of gold fluid in the low salinity in- acidic medium under reducing conditions and migrated to the surface or near shallow, gold-bearing fluid migration to the low pressure zone along the fracture, fracture filling, penetration, accountable, and ultimately the Au structural faults precipitate formed vein gold body.