Abstract:

The salt structures of various types formed in the massive Aptian saline rocks of the Lower Congo Basin against a passive continental margin setting are among one of the main factors that affect the accumulation of oil and gas in the basin.Based on seismic section interpretations of the Lower Congo Basin, this study analyzes the deformation characteristics and evolution processes of the typical salt structures, and discusses the factors affecting their development through cross-section balancing and restoration and physical modeling.The results show that the Lower Congo Basin is characterized by zonation under obvious structural deformation, with salt rollers, salt rafts, listric normal faults, and shovel-shaped faults developed in the back extensional zone, different forms of salt diapirs in the central transition zone, and salt canopies, thrust faults and thick-bedded salt rocks in the front compression zone of the basin.The salt structures have undergone three evolutionary stages, namely the initial active stage during the Albian-Late Cretaceous, the strong active stage during the Late Oligocene-Late Pliocene, and the weak active stage during the Late Pleistocene to the present.Gravity sliding and differential loading of overlying strata were the main controlling factors that led to plastic flow of the salt structures.The basement tilting was also involved in the deformation of the salt structures.

Key words: salt structure, balanced section, physical modeling, gravity sliding, differential loading, Lower Congo Basin,