Structural controls on sedimentation during asymmetric extension: The case of Sorbas Basin (SE Spain)

Abstract

Understanding the link between sedimentation and fault kinematics is important for reconstructing the evolution of sedimentary basins. The relationship between the mechanics of creating accommodation space and the sediment supply in asymmetric extensional basins is critical for quantifying their syn- and post-rift evolution, but is not yet well understood. One exceptional place to analyze such mechanics of normal faulting and its relationship with the evolution of depositional environments is the Sorbas Basin in the Betic Cordillera of SE Spain. We have analyzed the interplay between extension and deposition by means of a detailed sedimentological and field kinematic study. The results indicate a novel and coupled evolution, characterized by low-order tectonically induced sedimentary successions driven by the change of deformation style and high-order tectonically induced sedimentary successions driven by individual stages of fault activity. Fault mechanics and hanging-wall tilting control the formation of depositional slopes, while footwall exhumation induces enhanced sourcing of coarse sediments that may be stored in proximal areas or recycled in the basin during episodes of fault activity. Following initiation of extension, the subsequent syn-kinematic deposition was characterized by a wide spectrum of subaqueous gravity flows, whose types and transformation mechanisms were controlled by the style of normal faulting, sediment supply and basin physiography. Furthermore, the study quantifies the controls of rheological stratified sediments on normal faulting mechanics and their implications for the spatial and temporal basin evolution.