Reply to comment on ¡§Onset of the movement along the Ailao Shan-Red river shear zone: Constraint from 40Ar/39Ar dating results for Nam Dinh area, northern Vietnam¡¨ by . Journal of Asian Earth Sciences 18, 281¡V292

We hope that this reply can be of help in clarifying some fundamental aspects about the interpretation of thermo chronological data from the ASRR shear zone. As widely granted, in such a tectonically complex region these data must be considered with great caution particularly when one wants to explore the geodynamic implications. For the absence of direct methods, dating of various metamorphic mineral phases in highly deformed rocks from the shear zone by the 40Ar/39Ar methodology is probably the best way to study the cooling history of the metamorphic massifs and the timing of the strike-slip movement along the shear zone. Dating of leucogranitic intrusions within the shear zone may provide supplemental, though even more indirect, age constraints. Other igneous bodies that crop out away from the shear zone but have been claimed to have genetic links with the shearing movement should be carefully examined in the light of diverse magma throughout the region.