胶东地区夏甸金矿床构造蚀变带元素质量迁移与Au沉淀关系研究
Elements Migration in Tectonic-alteration Zones of the Xiadian Gold Deposit, Eastern Shandong Province and Its Relationship with Au Precipitation
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摘要: 夏甸金矿床是胶东招平断裂带内典型金矿床之一，金成矿作用与围岩蚀变关系密切。根据岩石结构构造和蚀变矿物含量，将夏甸金矿床围岩蚀变依次划分为：断层泥带、黄铁绢英质碎裂岩带、弱碎裂化糜棱岩带、碎裂化黄铁绢英质花岗岩带、碎裂化花岗岩带和正长花岗质碎裂岩带。通过对蚀变带蚀变矿物含量和Au含量分析，认为黄铁绢英质碎裂岩带是主要Au赋存带。选择相对蚀变较弱的X652-550-9样品为标准样，Y元素为守恒元素对黄铁娟英质碎裂岩带进行元素相对迁移量计算。分析结果表明，SiO2、Al2O3、Na2O和K2O迁移量较小，而LOI、MnO、P2O5、TiO2和MgO整体具有迁出的趋势；活泼元素（Au）在靠近主断裂F1迁移量较小，而靠近F2断裂迁入量显著提高，说明流体具有沿着主断层带（F1）对斜长花岗岩进行改造的特征，并且在整个黄铁绢英质碎裂岩带内各元素基本达到均一化，显示流体对围岩改造强烈，这与胶东地区大规模金成矿这一事实相吻合。Abstract: The Xiadian gold deposit is occurred as one of typical gold deposits in Zhaoping Au mineralization belt, eastern Shandong province, which is associated with extensively altered rocks. According to the structure and content of altered minerals in altered host rocks, the tectonic-alteration zones in this deposit can be divided into six subzones, such as fault gouge, beresitization cataclasite, weak fragmented mylonite, fragmented beresitization granite, fragmented granite and fragmented syenogranite. Based on the analysis of altered minerals and Au contents, it's found that the gold ore of the Xiadian deposit were mainly hosted in the beresitization cataclasite sub-zone.After selecting the relative weak altered sample (X652-550-9) as the standard sample while the Y element as the element conservation, the relative migration rate of elements in the beresitization cataclasite sub-zone has been calculated.The results show that the migration rate of SiO2, Al2O3, Na2O and K2O can be ignored, but LOI, MnO, P2O5, TiO2 and MgO show a emigrate trend.The migration rate of Au is low at the area nearby the F1 fault, whereas migration rate of Au increase significantly near F2 fault, which show that the plagiogranite (protolith) was altered by ore-forming fluids along F1, causing element homogenization in the whole altered zone. Inthe beresitization cataclasite zone, the characteristics of element migration rate indicate that the host rocks were extensively modified by faults and altered by ore-forming fluids, which are consist with the occurrence of numerous gold deposits in Eastern Shandong Province.
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