Tectonostratigraphic Evolution of the Brage Fault Zone, Norwegian North Sea

Abstract

This study investigates the tectonostratigraphic evolution of the Brage fault zone and suggests the fault is initially composed of six geometric segments that exert primary control on the general architecture of synrift stratigraphy.The hard linkage of these segments during Draupne times resulted in the obvious bend or jog that characterize the Brage fault trace. Isochron maps show isolated depocentres that are fault-parallel and in the hanging-wall of the Brage fault and other intrabasinal faults (Brage East and Brage Far West faults). The development of a major through-going Brage fault zone in Early Kimmeridgian-Ryazanian times resulted in a more open and continuous hanging-wall depocentre as accommodation creation became more uniform along fault strike. The Brage East and the Far West faults were intermittently active in the rift event and exhibits alternating activity with the Brage fault. The pronounced thickening of the lower Heather and upper Heather seismic stratigraphic units towards the Brage fault shows that the Brage fault was more active than the other intrabasinal faults. A pronounced fault parallel wedge-like geometry characterizes these units and is the result of a decrease in displacement along strike from the centre towards the tips of the fault. The findings of this study are consistent with those of other workers in the Norwegian North Sea and suggest that progressive linkage of initially isolated segments characterize the fault growth. The activity that alternates between the Brage fault and the Brage East fault also suggests that stress feedback between ruptures was probably an important mechanism controlling fault growth.