Investigating Fault Interaction and Linkage Within the Hoop Fault Complex, South Western Barents Sea, Norway

Abstract

This study presents a structural analysis of the Hoop Fault Complex (HFC) in the SW Barents Sea, Norway covering the area between 73°00'N, 22°00’ E and 74°30’ N, 26°30’ E. Seismic stratigraphy in 3D seismic of HFC is constrained using nearby well data and 2D seismic reflection data. Six seismic reflections were identified, namely the early Carboniferous, the late Permian, the early Triassic, the middle Triassic, the middle Jurassic and the base Cretaceous. From the time-structure map of the base Cretaceous, three seismic sections oriented at high angles to the trend of the faults were selected which represent contrasting structural configurations and are identified as a Northern (NGS), Central(CGS) and Southern (SGS) graben segment. The dominant strike of the structures is N-S (NGS) and NNE-SSW (SGS and CGS). We selected three main faults, all delineating the graben segments described above for detailed analysis and mapped throw distribution both vertically and laterally along main faults to illustrate the temporal and spatial changes in displacement distribution and sedimentation patterns to date coeval fault activity. Main faults in HFC have very distinct growth in Permian. The observations can be explained by either that isolated Carboniferous faults were reactivated and propagated up-section through evaporite layer into the Permian, forming fault scarp. This fault scarp trapped sediments, followed by nucleating younger faults affecting the Permian-Triassic. These segments propagated down-section and up-section and were hard-linked with older Carboniferous faults. The high throw is recorded in the early Permian which might be due to the sum of displacement accumulated by combined upward and downward propagation of younger faults. Alternatively faults nucleated inside the Permian-Triassic sequence and propagated radially, terminated into evaporite layer downwards. Fault linkage between shallower Cretaceous unit and Permian-Triassic is explained by that faults which nucleated in Cretaceous dip-linked to deeper sequences. Main faults in HFC were affected by multiphase rifting, but due to intervening ductile layers like evaporite and shale, strain is decoupled in area. Main events of synsedimentary fault activity were in early Permian, early Triassic, and Jurassic. Timing and evolution of main faults varies within the area and this knowledge is important, as this could impact the fluid flow.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015