福建碧田矿床冰长石的40Ar-39Ar年龄及其地质意义 |
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引用本文:.2003.40Ar-39Ar Dating of Adularia from Bitian Sericite-Adularia Type Epithermal Ag-Au Deposit in Fujian Province and Its Geological Significance[J].Mineral Deposits,22(4):360~364 |
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基金项目:国家重点基础研究项目“大规模成矿作用与大型矿集区预测”(编号:G1999043209) |
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中文摘要:采用40Ar-39Ar方法,测得碧田绢云母-冰长石型浅成热液Ag-Au矿床中与成矿同时的冰长石形成年龄为(94.69±2.25) Ma。这一结果显示,紫金山地区的酸性硫酸盐型浅成热液矿化比绢云母_冰长石型浅成热液矿化早5 Ma左右。综合目前的资料和测年数据,可以确定紫金山地区以花岗闪长斑岩为中心的斑岩_浅成热液成矿系统中水热-成矿事件的时间序列是(由先至后):花岗闪长斑岩侵位(105 Ma左右)→钾硅酸盐化及初始的Cu(Mo)矿化(104.5 Ma左右)→绢英岩化及含Cu_硫化物矿化(102.5 Ma左右)→明矾石化-硅化及酸性硫酸盐型浅成热液Cu-Au矿化(100 Ma左右)→冰长石化-硅化及绢云母-冰长石型浅成热液Ag-Au矿化(94.7 Ma左右)。从花岗闪长斑岩侵位至绢云母-冰长石型浅成热液Ag-Au矿脉定位,其间经历了约10 Ma。反映紫金山地区与成矿有关花岗闪长斑岩有较长的热历史。 |
中文关键词:地球化学 40Ar-39Ar定年 冰长石 碧田矿床 紫金山 福建 |
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40Ar-39Ar Dating of Adularia from Bitian Sericite-Adularia Type Epithermal Ag-Au Deposit in Fujian Province and Its Geological Significance |
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Abstract:The Bitian sericite_adularia type epithermal Ag-Au deposit is an important member in the intrusion_centered porphyry_epithermal metallogenic system of Zijinshan area. Adularia in the deposit, contemporaneous with Ag-Au mineralization, yields 40Ar-39Ar step heating age of 94.69~2.25 Ma. The dating result shows that the sericite_adularia type epithermal Ag_Au mineralization was formed 5 Ma later than the acid_sulfate type epithermal Cu_Au mineralization in Zijinshan area. Based on dating data available in combination with field relations, the authors have established the time sequence of hydrothermal and mineralization events in the intrusion_centered porphyry_epithermal metallogenic system of Zijinshan area as follows: intrusion of granodiorite porphyry (about 105 Ma)→potassic alteration and preliminary Cu (Mo)_mineralization (about 104.5 Ma)→alunite alteration, silicification and acid_sulfate type epithermal Cu-Au mineralization (about 100 Ma)→adularia alteration, silicification and sericite-adularia type epithermal Ag_Au mineralization (about 95 Ma). From the intrusion of granodiorite porphyry to the end of sericite_adularia type epithermal Ag_Au mineralization, the ore_forming process lasted about 5 Ma, which means that granodiorite porphyry related to mineralization in Zijinshan area had a relatively long heating history. |
keywords:geochemistry,40Ar-39Ar dating, adularia, Bitian deposit, Zijinshan, Fujian Province |
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