内蒙古赤峰北部下二叠统于家北沟组碎屑沉积岩地球化学特征  

GEOCHEMICAL CHARACTERISTICS OF CLASTIC SEDIMENTARY ROCKS FROM LOWER PERMIAN YUJIABEIGOU FORMATION IN NORTHERN CHIFENG,INNER MONGOLIA

作　　者：郭伟[1] 杨欣德[2] 张娟[1] 郝彬[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院地质力学研究所,北京100081

出　　处：《地质力学学报》2011年第3期295-302,共8页Journal of Geomechanics

基　　金：中国地质调查局"内蒙古1:50000炒米房幅(K50E006017);土城子幅(K50E006018);新开地幅(K50E007017);大黑水幅(K50E007018)区调"项目资助

摘　　要：内蒙古赤峰北部下二叠统于家北沟组碎屑沉积岩主要分布于华北克拉通北缘的内蒙古隆起。碎屑沉积岩主要以杂砂岩为主,源区岩石没有经过充分的搬运、分选,成熟度比较低。常量及稀土元素分析结果显示,轻重稀土元素分异明显,轻稀土元素富集,重稀土元素含量稳定,δEu的值在0.72～0.99之间,表现出一定的负Eu异常,与NASC或PAAS配分模式相似,说明物源来自于上地壳。结合前人的研究成果,认为其母岩原岩可能以沉积岩和花岗岩为主,或有少量的玄武岩;物源区大地构造背景为活动大陆边缘或者大陆岛弧,说明研究区在早二叠世或更早处于西伯利亚板块与华北克拉通缝合阶段。Located in northern Chifeng,Inner Mongolia,the clastic sedimentary rocks of Lower Permian Yujiabeigou Formation is mainly distributed at the Inner Mongolia uplift in the northern margin of North China craton.These clastic sedimentary rocks are dominated by graywackes,and their source rocks have not been fully handling and sorting,with relatively low maturity.The studying results have shown that light and heavy rare earth elements differentiate distinctly,and that light rare earth elements are obvious enrichment while the heavy rare earth elements stay stable.The values of δEu vary from 0.72 to 0.99,show negative Eu anomalies particularly and are similar with NASC or PAAS distributing model,which suggest that these sediments are sourced from upper crust.Combining with the predecessors＇ achievements,it is obtained that the original rocks of these sediments＇ parent rocks mainly are consist of sedimentary rocks and granites,with a small amount of basalt;The geotectonic background of these sediments＇ source area is active continental margin or continent island arc,which may show that this studying area is in the suture stage between Siberia plate and North China craton in Lower Permian or earlier time.

关 键 词：下二叠统 碎屑沉积岩 地球化学特征 活动大陆边缘 大陆岛弧 

分 类 号：P595[天文地球—地球化学]