摘要
采用40 Ar_3 9Ar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 .6 9± 2 .2 5 )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 5Ma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 (1 0 5Ma左右 )→钾硅酸盐化及初始的Cu(Mo)矿化(1 0 4 .5Ma左右 )→绢英岩化及含Cu_硫化物矿化 (1 0 2 .5Ma左右 )→明矾石化_硅化及酸性硫酸盐型浅成热液Cu_Au矿化 (1 0 0Ma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 .7Ma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 1 0Ma。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。
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 40 Ar_ 39 Ar 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.
出处
《矿床地质》
CAS
CSCD
北大核心
2003年第4期360-364,共5页
Mineral Deposits
基金
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 :G19990 43 2 0 9)
