山东招远金岭金矿埠南矿区1#脉流体特征及成矿物理化学条件研究

金岭金矿埠南矿区成矿流体成分特征显示流体为有幔源流体参与的岩浆水与大气水的混合流体。均一法测温表明成矿温度在 10 3～ 35 2℃ ,变化较大 ;通过Shenberger等和Hayashi等LogfO2 - pH图解 ,温度较低的成矿中期阶段 (2 5 0℃± )流体系统中的金明显比早期阶段 (30 0℃± )富集。成矿流体中金主要以Au(HS) -2 形式存在。根据含CO2 三相包体估算 ,流体压力在 5 1～ 70MPa之间。根据Sibson等断裂带流体垂直分带曲线 ,在流体压力为4 0～ 370MPa时 ,断裂带流体压力和深度之间为非线性关系 ,成矿深度既不能用静水压力梯度也不能用静岩压力梯度来计算 ,应该用特定的流体压力和深度关系式计算。通过分段拟合深度和压力之间的关系式计算出金岭金矿成矿深度在 5 .7～ 6 .78km之间 ;按照Gebre Mariam等提出太古代后生金矿深度分类 ,属典型中成脉型金矿。

STUDY ON FEATURES OF FLUIDS AND ORE-FORMING PHYSICAL-CHEMICAL CONDITIONS AT BUNAN GOLD MINE, JINLING DEPOSIT, SHANDONG PROVINCE

The fluid inclusion compositions of the samples from Bunan gold mine show that the ore-forming fluid is the mixture of magmatic water containing mantle fluid partially and meteoric water. The homogenization temperatures range extensively from 103 ℃ to 352 ℃ in mineralization period. According to the diagrams of LogfO_2-pH from Shenberger et al. (1989) and Hayashi et al. (1991), Au is apparently richer at the middle stage of lower temperature (250 ℃±) than at the early stage of higher temperature (300 ℃±) in the ore-forming fluid system. Au is mainly in the form of Au(HS)~-_2 which acts as the main species in the fluid. Based on the estimate about CO_2-bearing three-phase inclusions, the pressure of fluids ranges from 51MPa to 70MPa. According to the vertical curve of fluid within fault zone from Sibson et al. (1988), when pressure of fluids varies from 40 MPa to 370 MPa, neither hydrostatic pressure nor lithostatic pressure gradient can be employed, and the pressure of fluids in fracture zone shows non-linear relationship with depth. In that case, a specific formula between fault fluid pressure and depth can be constructed. According to the formula between sectional simulation pressure and depth, the ore-forming depth can be calculated and it is found that it is in the range from 5.7km to 6.78km, belonging to the typical depth for mesozonal vein-type gold deposit as defined by Gebre-Mariam et al. (1995).