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五里坝火山岩位于扬子与秦岭微板块的分界断裂:巴山弧两河—饶峰—石泉—高川蛇绿构造混杂带内,岩石为一套双峰式火山岩组合,由亚碱性玄武岩和亚碱性英安流纹岩组成。基性岩和酸性岩均具有显著的Nb、Ta亏损,玄武岩的Th/Yb-Ta/Yb和Ti/Zr-Ti/Y不活动痕量元素组合特征指示这套双峰式火山岩具有岛弧火山岩的地球化学特征,形成于特殊的洋内岛弧弧内裂陷的大地构造环境。五里坝火山岩应是勉略洋盆在古生代晚期—中生代早期发育期间洋壳俯冲及裂陷的岩浆作用产物。它可能是勉略缝合带在巴山弧地区出露的重要岩石学证据。
The Wuliba volcanic rock is located in the boundary fault between the Yangtze and Qinling microplates: the Bashan Arc Lianghe-Rao-Fengquan-Gaochuan ophiolite tectonic mixed zone, and the rock is a bimodal volcanic assemblage composed of subbasic basalt and subalkali Sexual rhyolite composition. Both basic and acidic rocks have significant depletion of Nb and Ta. The combination of Th / Yb-Ta / Yb and Ti / Zr-Ti / Y inactivation trace elements in basalts indicates that the bimodal volcanics have island arc volcanic rocks Of the geochemical characteristics, formed in the special intracontinental arc arc continental tectonic environment. The Wuliba volcanic rocks should be the product of magmatism from the subduction and rifting of the oceanic crust in the Mianloo Ocean basin during the late Paleozoic-Early Mesozoic. It may be an important petrological evidence that Mianlue sutures are exposed in the Bashan arc area.