中国东部宜溧地区周铁桥岩体的似埃达克岩特征  

On the adakite-like features of Zhoutieqiao rock mass in Yixing-Liyang area of eastern China

作　　者：蔡露明[1] 黄顺生[1] 杨用彪[1] 王丽娟[1] 

机构地区：[1]江苏省地质调查研究院,江苏南京210018

出　　处：《地质学刊》2017年第4期548-554,共7页Journal of Geology

基　　金：中国地质调查局项目"江苏宜溧地区铁铜矿远景调查"(1212011120855)

摘　　要：对江苏宜溧地区燕山晚期周铁桥岩体的岩相学、岩石地球化学特征研究得出:w(SiO_2)=57.84%~65.86%(大于56%),w(Al_2O_3)=14.70%~16.78%(绝大多数大于15%),Y含量为0.96~2.71g/t(<3g/t),(La/Yb)N比值为11.10~18.20(>10),与中国东部典型埃达克岩特征非常相似,表明它们形成于碰撞后拉张环境地幔玄武质岩浆底侵导致的下地壳部分熔融,埃达克岩的高温和高压萃取了大量Cu、Au元素,形成含铜金矿的热液,沿深大断裂在岩体内形成大面积矿化。The paper studied the late Yanshanian Zhoutieqiao rock mass from the perspective of petrography and petrogeochemistry. The result shows that its SiO2 content is between 57.84% and 65.86% （greater than 56%）, its Al2O3 content is between 14.70% and 16.78% （mostly greater than 15%）, its Y content is between 0.96 g/t and 2.71 g/t（less than 3 g/t）, its La/Yb ratio is between 11.1 and 18.2 （greater than 10）, which is rather similar to the features of typical adakite in eastern China. This result reveals that the Zhoutieqiao rock mass is formed in the post-collisional tensional environment, when mantle-derived basaltic magma underplating caused partial melting of lower crust. High temperature and high pressure of adakite helped extract massive Cu and Au, which formed hydrothermal fluid rich in Cu and Au and further contributed to massive mineralization along the deep major fracture of the rock mass.

关 键 词：周铁桥岩体 C型埃达克岩 高钾钙碱性 成矿物质 宜溧地区 江苏 

分 类 号：P588.122[天文地球—岩石学]