Abstract: There are 3-4 layers of volcanic rocks in Mid Jurassic sections at Tuoge, Duobagou and Lucaogou in Dunhuang basin between Xinjiang and Gansu, China. The volcanic rocks are composed of alkaline basalt within plate. The characteristics of trace element and Rare Earth Element(REE) of the Volcanic rocks indicate that it is similar to the alkaline basalt of the typical continental rift. According to the regional and basin analysis, the volcanic rocks were controlled by the same normal fault. From the lower to upper, the contents of the SiO₂ increase; and athe total REE increase from 0.00036093 to 0.00053349. This evolution is associated with crystallization differentiation. The total REE, La/Yb, (Ce/Yb)_cn and Sm/Nd are increased regularly from Tuoge To Lucaogou. The increase indicates that the thickness of the crust becomes thinner from Tuoge to Lucaogou.

Key words: volcanic rocks, geochemistry, Dunhuang basin, Mid-Jurassic

摘要： 敦煌盆地托格、多坝沟和芦草沟等地中侏罗世火山岩属于碱性玄武岩，其微量元素和稀土元素特征表明，该火山岩与典型大陆裂谷碱性玄武岩相似，属于张性作用的产物。区域和盆地分析说明，三地区火山作用受同一条张性断裂控制。火山岩地球化学纵向上的演化受结晶分异作用的控制，横向上的变化，受地幔隆起程度和部分熔融程度影响。

关键词: 火山岩, 地球化学, 敦煌盆地, 中侏罗世