The ordovician is outcropped in peripheral of Tarim basin and was encountered in drilling of main structure of the cover area.

• 塔里木盆地奥陶系出露于盆地周缘并在覆盖区主要构造单元钻遇。覆盖区奥陶系包括台地相、斜坡相和槽盆相三大类型；