资源环境科技发展态势分析平台

Multiple episodes of rifting and preexisting structure reactivation may result in rift segmentation, which is a fundamental factor in deformation variability and sediment dispersal. To understand the structural framework and basin evolution in segmented rift systems, this study addresses an integrated structural and stratigraphic analysis of the Middle–Upper Jurassic sequences in the northern North Sea. Four major fault systems were active during the Jurassic oblique rifting: (1) east-northeast–striking synthetic shear faults along preexisting Caledonian structures, which developed into basin-wide transfer fault zones and induced first-order rift segmentation. Each rift segment shows independent deformation; (2) north-south–striking reactivated Permian–Triassic faults, which uplifted the footwall developing major structural highs; (3) southwest-northeast–striking normal faults; and (4) northwest-southeast–striking antithetic shear (oblique-slip) faults, which caused internal deformation and induced second-order rift segmentation within rift segments. Rift segmentation led to stepovers from the Viking graben to the Sogn graben. The entry of regional drainages was determined by first-order rift segmentation. Prior to segmentation (Bathonian–Callovian), drainage shows a northeast-southwest line-source nature, and facies changes are quite homogenous. During the Oxfordian–Kimmeridgian, segmentation took place and modified the drainage system into a point source. Facies show a large spectrum of variability from shallow-marine to deep-water turbidites over short distances. Furthermore, drainage routes were influenced by second-order rift segmentation. West-directed drainages deflected toward the northwest by adapting to gradient surfaces established by oblique-slip faults. As such, the structural and stratigraphic expressions in this study provide an example of synrift deposition controlled by different orders of rift segmentation.