摘要
广泛分布于扬子地台西缘康滇地轴上的康定杂岩,其形成时代一直争议较大。选取前人少有涉及的大田地区混合岩进行LA-ICP-MS锆石U-Pb年龄测定,结果表明,其年龄时限集中在744~772Ma之间,为晋宁造山运动期产物,与近年其他学者针对康定杂岩的锆石测年结果一致,说明康滇地轴最大一次混合岩化作用发生在晋宁期。混合岩稀土元素具2种明显不同的配分型式,显示深熔作用特征。深熔作用早期混合岩Eu具正异常特征,晚期则具明显的负Eu异常,显示有分异结晶作用。有利的铀矿赋矿围岩为深熔作用晚期分异结晶形成的混合岩。
The Kangding complex that is extensively distributed in the Kangdian Axis on the western margin of Yangtze Platform is greatly disputed in terms of its formation age. In this paper, migmatite in Datian region which has rarely been referred to before was selected to perform U-Pb zircon LA-ICP-MS age determination. The results show that the ages are mainly concentrated from744 Ma to 772 Ma, suggesting that the complex was formed in Jinning orogeny period; moreover, this conforms to the zircon dating results specific to the Kangding complex presented by other researchers, which further indicates that the strongest migmatization event of Xikang-Yunnan Axis occurred in the Jinning period. There exist two distinctly different REE patterns of the migmatite which indicates geochemical characteristics of anatexite. At the early stage of anatexis, the magmatite produced positive anomaly of Eu; whereas at the later stage, Eu negative anomaly implying a process of differentiation crystallization was produced. The beneficial host rock of uranium mineralization is the magmatite formed by differentiation crystallization in the late period of anatexis.
出处
《地质通报》
CAS
CSCD
北大核心
2017年第2期381-391,共11页
Geological Bulletin of China
基金
中国核工业地质矿产事业部生产项目《四川西部地区铀矿资源调查评价与勘查》(编号:201638)
