新疆三塘湖盆地晚古生代火山岩地球化学特征及构造环境

GEOCHEMICAL CHARACTERISTICS OF UPPER PALAEOZOIC VOLCANIC ROCKS AND THEIR TECTONIC SETTINGS IN THE SANTANGHU BASIN,XINGJIANG

新疆三塘湖盆地的早石炭世玄武岩类岩石，具有Ａｌ２Ｏ３含量高，铁含量低，ＴｉＯ２含量低，大离子亲石元素及轻稀土元素富集的钙碱性系列特点。利用图式差别表明，该区在早石炭世处于岛弧的构造环境。早二叠世安山岩的岩石化学特征、稀土元素和微量元素丰度具钙碱系列中高钾造山安山岩特征，与安第斯活动大陆边缘安山岩的元素特征相似。证实三塘湖地区在早二叠世时期处于西伯利亚板块活动陆缘的构造环境。

The geochemical analysis indicates that the Early Carboniferous basalts in the Santanghu basin are characterized by higher Al 2O 3,lower FeO,Fe 2O 3 and TiO 2,and by high concentrations of large ion lithophile element(LIL) and LREE,showing the characteristics of the calc alkaline series.In addition,results of discriminant analysis show that the Santanghu area was in an island arc setting during Early Carboniferous.The petrochemical characteristics and REE and trace element abundance show that the andesites of Early Permian belong to high potassium orogenic andesites of calc alkaline series,comparable with that of the Andes type active continental margin,indicating that the Santanghu area was in the active continental margin of Siberia plate during Early Permian time.