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二龙屯地区火山岩由晚侏罗世满克头鄂博期和早白垩世满克头期火山岩组成,主要岩性为安山岩、粗安岩、英安岩、流纹岩、安山质含角砾岩屑晶屑凝灰岩、英安质含角砾岩屑晶屑凝灰岩、流纹质含角砾岩屑晶屑凝灰岩等。满克头鄂博期火山岩富硅、碱,贫铁、镁、钙,属于过饱和类型火山岩、高钾火山岩。该期火山岩稀土元素含量中等,具有明显的负铕异常。梅勒图期火山岩以中性为主。Si O2含量中等,碱质含量高,钙碱性系列高钾火山岩。其稀土元素含量中等,重稀土相对亏损,并且有比较明显和不明显的负铕异常。综合满克头鄂博期火山岩与梅勒图期火山岩的地球化学特征,认为二龙屯地区晚侏罗世—早白垩世火山岩形成于活动陆缘火山弧构造环境。
The volcanic rocks in Erlongtun area consist of Late Jurassic Mancocko Ebo and Manchurian volcanic rocks of Early Cretaceous. The main lithology is andesite, coarse andesite, dacite, rhyolite and andesitic breccia debris Crystal tuff, the British amphibolite-bearing breccia debris crystal tuff, rhyolitic breccia debris containing crystal tuff and so on. Manchu Ebo volcano rocks rich in silicon, alkali, iron deficiency, magnesium, calcium, belong to the type of supersaturated volcanic rocks, high-potassium volcanic rocks. During this period, the REE content of the volcanic rocks is medium and has obvious negative europium anomaly. Mailer map volcanic rocks to neutral. Si O2 content of medium, high alkaline content, calcium alkaline series of high potassium volcanic rocks. The content of rare earth elements is medium, heavy rare earth relative loss, and there is more obvious and not obvious negative Eu anomaly. Based on the geochemical characteristics of the volcanic rocks in Manke Og Ebo Period and the Maileru volcanic rocks, the Late Jurassic - Early Cretaceous volcanic rocks in Erlongtun area are formed in the active continental margin volcanic arc tectonic setting.