GEOLOGICAL MODEL OF THE MUGLAND BASIN-AN IDENTICAL EXAMPLE OF BASIN EVOLUTION AT THE END OF GIANT STRIKE-SLIP FAULTS

The basin evolution at the end of giant Central African strike slip fault is closely related to the regional tectonic background.Evolution of the basin in the Early Cretaceous resulted from the seperation of Atlatic Ocean,and that in the Later Cretaceous from the northward movement of the India plate.The spreading of Red Sea in the Cenozoic have also influenced the evolution of the basin.Three stages of the structural evolution for the basin can be classified:Early Cretaceous,Late Cretaceous and Cenozoic.In the Early Cretaceous,owing to activity of the central African strike slip fault,the subsidence speed was enormous,in which the depositional and subsiding centers were not in the same position.In the Late Cretaceous,the basin was dominated by both rifting and sag,and the depositional center moved towards the southeast of the basin where was far away from the central African fault.In general scene,the structural evolution for the basin was transformed from the strike slip to the extensional system.Potential source rocks and reservoirs were developed along the central African fault in the early evolution of the basin.Under the structural compression in the late stage,some oil and gas pools could be destroyed,and resulted in hydrocarbon redistribution and formation of new accumulations.The difference in depositional and subsiding centers brought out the difficulty in exploration.In the southeast of the basin far away from the central African fault,the main source rocks were matured properly,and depositional and subsiding centers were in the same place,so many industrial oil and gas fields have been found.