摘要
The Early Mesozoic tectonic and geodynamic evolutions of the South China Block(SCB) are still debated questions. Along the southern margin of the SCB, the Yunkai and Song Chay massifs are key regions to address these questions. In both of these massifs, an Early Mesozoic ductile deformation with thrust and folds structures have been observed. Geochronological works indicate the time of deformation around 220 Ma. In north Vietnam, the Song Chay massif presents quite similar lithological and structural features with the Yunkai massif. Furthermore, the newly discovered Song Chay ophiolitic suture might account for the Triassic plate boundary in the southern margin of SCB in North Vietnam. The Yunkai and Song Chay massifs, that both belong to the southern margin of SCB, are involved in this Indosinian orogenic belt that probably extends in NW China along the Jinshajiang.