| 小秦岭与胶东金矿床的成矿流体特征对比 |
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| 引用本文：.1997.A comparison of ore-forming fluids between gold deposits in Xiaoqinling Mountains and those in Jiaodong peninsula[J].Mineral Deposits,16(2):151~162 |
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| 基金项目:北京科技大学科研专项基金 |
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| 中文摘要:小秦岭和胶东地区绿岩型金矿床的矿化类型和成矿流体的包裹体、稳定同位素特征有很多相似之处，但也有些区别。小秦岭金矿床的流体包裹体具更高的CO2/H2O、较低的K+/Na+和F-/Cl-，这与该区的成矿压力较高、容矿主岩以相对贫K+、F-的斜长角闪岩和灰色片麻岩类有关。而胶东地区金矿床的容矿主岩则以富K+、F-的长英质岩石为主。小秦岭金矿床较低的δ18O值、胶东地区δ18O值随着距海岸位置的变化等现象均表明这两个地区金矿床的成矿溶液与大气降水有着密切联系。 |
| 中文关键词:金矿床 成矿流体 小秦岭 胶东 |
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| A comparison of ore-forming fluids between gold deposits in Xiaoqinling Mountains and those in Jiaodong peninsula |
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| Abstract:Gold deposits both in Xiaoqinling Miountains and in Jiaodong Peninsula occur within the Precambrian granitoid-greenstone terrains, controlled by ductile shear zones or ductile-brittle fracture zones. They have many similarities in mineral paragenesis, wallrock alteration, fluid inclusions and stable isotope composition. Ore-forming fluids are characterized by low salinities (generally lower than 10 equiv. wt% NaCl) and relatively high CO2 contents. Fluid inclusions in the main ore-forming stages are rich in CO2; nevertheless, in earlier quartz of altered rocks, fluid inclusions containing NaCl crystals can be seen. The homogenization temperatures vary from 250 to 350℃ (even up to 450℃) during the early stage and from 150 to 250℃ (even down to 100℃) in the late stage. The CO2/H2O ratios of fluid inclusions in Xiaoqinling Mountains are higher than those in Jiaodong, suggesting that ore-forming pressure was higher in Xiaoqinling Mountains than in Jiaodong. K+/Na+ ratios of fluid inclusions in quartz have much to do with host rook, being usually higher than 1.0 in gold deposits related to felsic host rock while lower than 1.0 in vein gold deposits related to dioritic or mafic host rock. Measured δD values of fluid inclusions and calculated δ18OH2O in vein quartz of both areas indicate that the water of ore-forming fluids was associated with meteoric water. The observed difference between the two areas may have resulted from elevation and/or continental effect. δ34S values of sulfides from gold deposits in both areas indicate that sulfur might have originated from the process of granitization in the basement. However, the higher δ34S values in Jiaodong than those in Xiaoqinling Mountains may also imply the influence of the underground water affected by paleo-sea water rich in 34S. |
| keywords:gold deposit, ore-forming fluid, Xiaoqinliing Mounrains, Jiaodong |
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