Identification of the island-are magmatic zone in the Lianghe-Raofeng-Wuliba area, south Qinling and its tectonic significance

Detailed studies indicate that a typical island-are magmatic zone exists in the Lianghe-Raofeng-Wuliba area of south Qinling. This is characterized by continental marginal andesite and bimodal volcanic rock association which was formed in a rift environment within an oceanic island-arc. The island-a re magmatic zone is the product of Devonian-Carboniferous oceanic crust sub duction and rifting of Mianlue ancient oceanic basin. The presence of the i sland-are magmatic zone suggests that the Mianxian-Lueyang suture zone had extended to the Bashan arcuate area. The Sunjiahe volcanic rock association of the Xixiang Group formed in a volcanic-are setting which should have a close relationship with Mianlue suture zone.