Characteristics and Tectonic Setting of Jiabeila Formation Volcanic Rocks in the Area between Suojian and Zhiduo, Eastern Qiangtang

Jiabeila Formation volcanics are an intermiate-mafic suits of alkaline basalt and trachyandesite.The rocks are low in TiO2(1%)and Al,riched in light rare earth elements geochemically.Trace elements are charactered by large ion lithophile element richment and high field strength element fractionation.Their eSr()tranges from 42.6 to 53.4 with eNd()tfrom-2.2 to-2.4,which showing the volcanics arc property.And they are probably the products of the southward subduction of Gangzi-Litang oceanic slab.