The Role of Footwall Release Faulting in Controlling Structural Closures in Rift Systems: Evidence from the Murchison Fault Array, Northern North Sea

Caroline E. Gill and John R. Underhill
University of Edinburgh, Edinbugh, United Kingdom

Extensional fault growth and linkage plays an important role in the development of rift systems. Recent results have highlighted the main controls on structural styles and their effects on the temporal and spatial evolution of basin physiography, stratigraphic geometries and sediment dispersal in rift basins. However, little application of these controls has been made to analogous subsurface examples. This study uses temporally-constrained, densely-spaced 3D seismic data from the highly prospective East Shetland Basin, northern North Sea to document the evidence for, and effects of footwall deformation during the Late Jurassic syn-rift episode

Interpretation of structures in the footwall to the Murchison Fault in the East Shetland Basin shows an associated array of strike perpendicular syn-sedimentary faults. The faults, termed herein footwall release faults, range in length and displacement but all show a marked decrease in displacement away from the main structure. There are no partner structures in the hangingwall where deformation is accommodated on open, long wavelength folds. These structures are the main control on the size and location of structural closures along the Murchison Fault.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005