摘要
本文由兰坪盆地内金顶超大型矿床容矿围岩中的孢粉组合特征、铅同位素年龄和稀土元素特征等证据判断,其围岩灰岩角砾岩和砂岩的成岩年代和铅锌主矿化的时期一致,均属中-晚三叠纪,约在235Ma±。结合区域构造演化认为它属于碰撞后裂谷环境下的热水沉积矿床。这一认识一改过去新生代陆相盆地成矿的观点,对矿区内的构造、矿体的分布特征、矿质来源等一系列矿床地质问题均得到了较合理的解释。
Jinding superlarge deposit located in the northern part of Lanping Basin, western Yunnan Province. It has been studied for more than 20 years, and a lot of genetic models were proposed such as stratabound type, synsedimentation-late reformation and mantle-crust compound mineralization. But some elementary geological problems such as some of the host rock ages and the structures that constrained orebodies have been suspended till now. Recently the age of the wall rocks of Jinding deposit was dated by common lead and sporopollen assemblage.The yielding age of 235 Ma ± belonged to Middle- late Triassic. And Jinding deposit might be syndeposit in a rift (similar to SEDEX type ) after the collision of Zuogong-Baoshan micro-plate and Yangtze plate. This changed the genie view that Jinding deposit was formed in intraplate basin of Cenozoic in the past. It also explained commendably some geological problems such as the distribution of Pb-Zn orebodis and occurrences of fracted structures of the orebodies in Jinding deposit.. According to lead isotopes, the metallogenetic elements were from upper crust not from mantle.
出处
《地质调查与研究》
2006年第4期294-302,共9页
Geological Survey and Research
基金
国家重点基础研究发展规划项目(2002CB412607)
关键词
金顶矿床
围岩
孢粉
铅同位素
地质年代
Jinding deposit
host rocks
lead isotope
sporopollen assemblage
geological time