1.The Rb-Sr isochron ages of 719 Ma and 726. 6 Ma obtained respectively from biotite schist-staurolite schist and plagioclase-hornblende schist indicate that basement metamorphic rocks in Xiangshan area must be attributed to Neoproterozoic rather than Caledonian.
2.In the ocean basin spreading stage of Middle Silurian,it formed a increase metamorphic charateristics with lotrite facies→low green schist facies→hornblende facies.
