中文摘要：

本文对新疆北山矛头山东一带火山岩野外地质特征、岩石学、岩石地球化学和锆石u-Pb年龄进行了系统研究。该区火山岩岩石组合为玄武岩、玄武安山岩、安山岩和同成分的火山碎屑岩。该套火山岩中锆石SHRIMPU-Pb年龄表明．其形成时代为早二叠世。其岩石地球化学特征显示为-套钙碱性火山岩，富集轻稀土元素，无明显的负铕异常：大离子亲石元素Rb、Th、u相对富集，Ba、Sr略有波动。高场强元素Nb略有亏损、Ta亏损明显。综合分析，笔者认为该套早二叠世的火山岩形成于已经充分收缩的残余海盆环境；此时北山的构造属性更与残余海盆的陆缘火山盆地相似．而不具有裂谷的特征。

英文摘要：

The field geological features, petrology, lithogeochemistry and high degree of accuracy isotope chronology of volcanic rocks in eastern Maotoushan of Beishan area, Xinjiang, are discussed in this paper. The rock association of this area is composed of basalt, basaltic andesite, andesite and tuff with the same components. U-Pb isotope SHRIMP dating shows that the eruption time of volcanic rocks should be Lower Permian. The volcanic rocks are of the calc-alkaline series. No obvious KEE fractionation and clear negative Eu anomalies are observed, and there exist enrichment of kb, Th and U, slightly fluctuation of Ba, Sr, and loss of Nb, Ta. An integrated analysis led the authors to believe that the early Permian volcanic rocks were formed in a fully shrunk residual sea basin environment, and the structural attributes at that time were similar to features of the epicontinental volcanic basin of the residual sea basin instead of having the characteristics of the rift.