Deformation and Evolution of Aptian Salt Tectonics in the Central Lower Congo Basin: Integrated Analogue and 3D Discrete Element Modelling

Peng Cheng^1*Yanxin Qi²Jiasen Zhao³

• ¹School of Remote Sensing and Information Engineering, North China Institute of Aerospace Engineering, Langfang, China
• ²School of Information Science and Engineering, Baoding Institute of Technology, Baoding, China
• ³North China Institute of Aerospace Engineering, Langfang, China

The Lower Congo Basin, a salt-rich passive margin basin, displays complex interactions between salt tectonics and sedimentation that significantly influence hydrocarbon systems. To investigate the deformation and evolution of Aptian salt structures in the central Lower Congo Basin, this study integrates physical analog modeling with three-dimensional discrete element method (3D DEM) simulations. The analog experiments replicate basin-scale gravitational spreading followed by obstruction-induced compression, while 3D DEM captures salt–sediment interactions, strain localization, and salt flow anisotropy at the diapir scale. Results delineate a three-stage evolutionary framework: (1) a Global Extension phase marked by salt raft development and passive diapirism; (2) a Frontal Obstruction phase in which volcanic basement highs halt salt spreading, localizing compressional stress; and (3) a Compression Propagation phase that generates squeezed diapirs with mushroom and teardrop geometries. Pre-existing diapirs act as strain sinks, focusing deformation and producing velocity anomalies and "stress-release windowschimney effects.". Depocenters migrate toward active diapirs due to salt withdrawal and sediment loading feedbacks. The models successfully replicate natural structures observed in seismic profiles, justifyvalidating their predictive capability. These findings advance understanding of salt tectonic evolution in passive margins and provide insights into structural controls on hydrocarbon trap development in salt-bearing basins.