吉林省中部大口钦地区营城组流纹岩地球化学特征

Geochemical characteristics of rhyolites in Yingcheng Formationfrom Dakouqin area in central Jilin Province

本文对吉林省中部大口钦地区营城组流纹岩进行了岩石学和地球化学研究,结果表明:流纹岩以富硅、贫钙、贫镁、贫铁为特征,在地球化学上具有典型A型流纹岩特征。在痕量元素组成上,富集LREE和LILE元素(如K、Rb、Th、U),亏损HREE和HFSE元素(如P、Ti),具强烈的负Eu异常。其原始岩浆来源于下地壳的部分熔融,形成于滨太平洋板块俯冲引起的加厚岩石圈拆沉后的伸展环境。

In this paper,the petrology and geochemical of rhyolites in Yingcheng Formation from Dakouqin area in central Jilin Province are studied.The results show that the rhyolite are characterized by rich silicon,poor calcium,poor magnesium and poor iron,and A-type rhyolite in geochemistry.They are enriched in LREE and LILE(such as K,Rb,Th,U),and depleted in HREE and HFSE(such as P,Ti),with strong negative Eu anomaly.The rhyolites could be derived from partial melting of lower crust and formed in the post-orogenic extensional environment caused by the subduction of peri-Pacific Plate to Eurasian Plate.