Evolution and character of supra-salt faults in the Easternmost Hammerfest Basin, SW Barents Sea
Abstract This study investigates the evolution of supra-salt faults in the Eastern Hammerfest Basin using high–quality seismic reflection data. Traditional techniques of displacement analysis, including the variation of fault displacement (throw) against distance (x), depth (z), expansion and growth indices were adopted. Fault reactivation was assessed using bivariate plots of a) cumulative throw vs. age and b) throw (t) vs. depth of nine (9) representative faults. The interpreted faults are supra-salt crestal and synclinal faults striking NE, E and SE. These faults have complicated t-x and t-z plots and are characterized by considerable stratigraphic thickening in their downthrown section. Faults in the study area have developed over the salt structure since latest Paleozoic times; some of them were reactivated by Early to Middle Triassic through dip linkage of initially isolated fault sets. Along strike, the fault exhibit complex segmentation through coalescence of several subunits linked by local throw/displacement minima. Expansion and growth indices show that the faults of the study area developed during the deposition of Paleozoic to Early Cretaceous sediments by polycyclic growth involving both blind and syn-sedimentary activity. An important piece of information from this study is that fault propagation is controlled by lithological heterogeneity and that both lateral and vertical segmentation of faults are important for hydrocarbon migration within the Triassic to Late Cretaceous interval.