Abstract:

Development of the Cambrian subsalt structures in central Bachu area has mainly been controlled by fault movements.The present structural traps have been modified by multiphase tectonic movements.Kabei,Gudongshan and Karasay structures have reached their optimal trap shapes in Late Hercynian and Early Mesozoic,respectively.The structural traps have then been modified and destroyed by later structural movements,as a result,Kabei structure has been transformed from anticline into faulted anticline,while Karasay structure from anticline into faulted anticline and faulted nose.The closures of both structures have been reduced to some extent.In contrast,Gudongshan structure has lost the condition of forming relatively large local traps,because later faults have broken the original structural traps into strips,and the Himalayan tectonic movement has unevenly uplifted the structural belt and become low in the south and high in the north.Kangtakumu structural trap has been formed in a relatively short time,i.e.it has been formed in Middle Himalayan and strengthened in Later Himalayan stage,and the closure has also been enlarged.

Key words: central Bachu area, Cambrain, fault movements, structural trap