Influence of lower crustal heterogeneity on rift tectonic evolution:a case study of the central south Atlantic rift basin
The basement morphology of the conjugate continental margins in the central South Atlantic varies from south to north along the strike,with the northernmost Camamu-Gabon Basin conjugate continental margin being an asymmetrical narrow rift margin,and the southernmost Santos-Namibe Basin conjugate continental margin being an extremely asymmetrical ultra-extended rift margin.The asymmetry of basin structure is controversial at present.Therefore,numerical simulation experiments based on finite element method to solve the viscoplastic continuous medium constitutive equations are carried out in this paper to explore the influence of lower crustal heterogeneity on rift tectonic evolution.The results of the experiments indicate that due to the lateral heterogeneity of the crust,narrow basins can be formed on the side with a stronger lower crust near the Craton,and wide basins can be formed on the side close to the orogenic belt with weak lower crust.When there is a thicker lower crust on the side near the orogenic belt,the mantle can change the crust-mantle coupling during upwelling and form a premature rift near the lithosphere of the orogenic belt,which affects the evolution of the basin.The rheological properties of the crust will determine the basic morphology of the basin.At the same time,when the crustal thickness changes,the degree of crust-mantle coupling will change,which will affect the direction of strain propagation and then affect the formation of the basin.
万方数据
