Discovery of Silurian in middle section of south belt of Beishan mountain and its geological significance, Gansu

The paper made more research on volcanic rock in Xiaocaohu-Yaodongliang area about rock association metamorphic trait and deformation intensity,volcanic sequence etc on the basis of mapping data of the 1:250000 Mazongshan sheet. And make a comparison of regions on the basis of rock association metamorphic trait and deformation intensity etc,and the whole-rock Rb-Srage of the Yaodongliang basic volcanic rock is in the range of 417.24±19.29 Ma,the alkali-feldspar granite which irrupted the basic volcanic rock and where Leidunzi eastern mountain is 238 Ma,so its age belongs to the Silurian.