Sm Nd ISOTOPIC AGES OF THE SONGSHUGOU OPHIOLITE FROM THE EAST QINLING AND ITS GEOLOGICAL SIGNIFICANCE

The Songshugou ophiolite consists mainly of meta perdotite and meta basalt. Five whole rock samples of meta basalt give a Sm Nd isochron age of （1030±46 ） Ma with I Nd =0.51161±5 （2δ） and ε Nd （t） = +5.7±0.2, which may represent the formation age of the basalt. This age gives some important information about the Middle Late Proterozoic tectonic framework in the Qinling region.