There occurred strong extension of lithosphere with NE direction in Cathaysian Block, East Sea and Japan Sea since 17 Ma, which also turned the movement direction of Indochina block from left lateral to right lateral slip.

• 17Ma以后,华夏、东海至日本海岩石圈均出现了强的NE向伸展,也使印支块体沿红河断裂从左旋挤出转向右旋走滑。