Abstract:

According to the data of seismic, aeromagnetic, well drilling, etc, the authors restudy the characteristics of the fault system in Yitong basin, analyzes its evolution and the control effect on the hydrocarbon accumulation. Yitong basin is a strike-slip stretching basin which is controlled mostly by the strike-slip fault of the north-west boundary in Cenozoic. The features and evolution of the basin’s faults are very complex, the faults can be classified as three distinction based on their characteristics and sizes.The first distinction faults include the north-west boundary fault and the south-east boundary fault; the second distinction faults include the stretching faults such as Maanshan fault, number 2 fault, number 3 fault, number 4 fault and the thrust fault along the north-west edge; the third distinction faults include the rest faults of the basin. The faults’ evolution features in Yitong basin took place in the regional dynamic setting that back-arc spreading caused by westward subduction of the Pacific plate, and the collision from the Indian plate also played a partial role in the E-W compression in the East China. Besides this, the distribution and uplift strength of rigid plates of Daheishan and Nadanhadaling Mountain play a great role on the fault evolution. The fault evolution includes two stages: the early dextral strike-slip stretching stage and the dextral strike-slip compressing stage in basin’s reverse period. The dextral strike-slip compressing forms the fault-folds belt by the north-west edge and it has great potential for hydrocarbon exploration.

Key words: fault system, boundary fault, fault evolution, Yitong basin