Characteristics And Evolution Of Ore-forming Fluid In The Sizhuang Gold Deposit, Jiaodong Peninsula

Sizhuang gold deposit is typical of altered rock type gold deposit in the Jiaodong gold metallogenic province. This article tidied predecessors’ research results and existing problems, integrated characteristics of ore-forming fluid and ore-forming fluid evolution process setted in a time-space structure, this paper of Sizhuang gold deposit, discussed the mechanism of gold mineralization through field and indoor work detailedly, get the following understanding:1. Sizhuang gold deposit hydrothermal mineralization can be divided into four stages: pyrite-quartz-sericite stage（ Ⅰ）, quartz and pyrite stage（ Ⅱ）, quartz-polymetallic sulfide stage（Ⅲ） and quartz and calcite stage（Ⅳ）, of which gold mainly occurrences in the pyrite of Ⅱand Ⅲ stage.2. Through studying fluid inclusions shows that three mineralization types of ore body in the Ore-forming fluid properties difference is not big, whole indicate that the ore-forming fluid is consistent, are in the low temperature（160³60 ℃）, low salinity（3.00¹1.83 wt % NaCl. Eqv）, low density（1.506¹.017 g/cm3） system of CO₂-H₂O-NaCl. Aqueous inclusions Tm Ice range is-4 to 0 ℃, ThTOT range 183¹83 ℃; H₂O-CO₂ inclusions TmCO₂ range of 60.5⁵6.2 ℃, the Tmclath range 3.4⁹.8 ℃, the ThCO₂ between 17.6¹7.6 ℃（< 31.1℃）, generally have lower trend first, then the trend of rising slightly, in addition to CO₂ inclusions,the other two types of inclusions’ ThTOT range is 160³60 ℃, the mine stage ThTOT peak appeared in the 270³00 ℃.3. Through the hydrogen and oxygen isotopic composition and water-rock reaction research, Sizhuang gold deposit in metallogenic early stage source of ore-forming fluid is mainly original metamorphic water Jiaodong group, in the stage into the mine Jiaodong group of original metamorphic water and meteoric water in between 4:1 react to 2:1 mixed with linglong granite most conducive to mineralization. The ore-forming fluid of atmospheric precipitation to join in the process of evolution.4. Sizhuang gold deposit underwent caused by pressure fluctuation not immiscible fluid, its accompanying Au（HS）₂^- solubility decrease is the main cause of gold deposits.5. Three types of mineralization types of ore bodies in similar ore-forming fluid characteristics, the main reason for the difference is: the ore structure altered rock type ores for gentle-dip slope surface. Gentle-dip slope fracture zone near the main faults; Quartz vein type ore of ore structure is steep dip angle extensional second-order faults.