新疆东昆仑祁漫塔格群火山岩建造成因初析

新疆东昆仑祁塔格群中有大规模的玄武岩、安山岩等中，基性火山岩活动的证据，地球化学研究表明，这些火山岩形成于海沟－岛弧环境；玄武岩的稀土元素分布模式总趋势为轻稀土元素略亏损的平坦型，与洋脊玄武岩类型；安山岩轻稀土富集；所有样品均具有轻微的Ｎｂ负异常和明显的Ｔｉ、Ｐ负异常。在各种构造环境判别图解上，样品主要落入洋中脊和岛弧环境。这一发现为证明新疆东昆他古生代岛弧环境提供了重要的证据，为进一步揭示昆仑造

TECTONIC ENVIRONMENT ANSLYSIS ON VOLCANIC ROCKS FROM QIMANTAGE GROUP, EAST KUNLUN OROGENIC BELT, XINJIANG

Basalt and andesite were discovered in Qimantag Group in Eas Kunlun Orognic Belt of Xinjiang on a large scale. Geochemical characteristics of andesite, for example, high LREE abundance and negative anomaly of Nb, Ti, P, which is obviously the result of subduction suggests that the andesite be formed in a typical island arc environment. The geochemical characteristics of basalt, as the same as oceamic tholeiite, suggests that the basalt be formed on the mid-oceanic ridge. This discovery is an important evidence that supports the existence of an ancient island arc in Qimantag area. It also gives some useful information about the tectonic pattern and the evolution history of East Kunlun Orogenic Belt.