北祁连山西段早奥陶世阴沟群火山岩的构造背景

早奥陶世阴沟群火山岩的地质－地球化学特征的研究结果表明，该期火山岩的岩石组合为玄武岩－安山岩组合，缺乏酸性火山岩和橄榄玄粗岩系列火山岩。其地球化学特征表明它们属于岛弧钙碱性火山岩，以富集ＬＲＥＥ和低离子位不相容元素以及亏损高场强元素为特征。火山岩形成于具有中等成熟度的岛弧环境，其中发育于东水峡的火山岩可能形成于弧内裂谷环境。

Geology and Geochemistry of Volcanic Rocks of the Early Ordovician Yingou Group in the Western Part of North Qilian Mountain and Their Tectonic Setting

Geological and geochemical characteristics of the Early Ordovician volcanic rocks from North Qilian Mountain show that they are of the basalt-andesite association with no acid rocks or volcanic rocks of the shoshonite series. Their geochemical features indicate that they are of the calc-alkaline series characterized by enrichment of LREE and LILE and depletion of HFSE. They were formed in an island-arc environment of moderate maturity, and the volcanic rocks present in Dongshuixia area might have been formed in an intra-arc rift.