Christopher Aiden-Lee Jackson , Stephen Corfield, Tom Dreyer

Integration of three-dimensional seismic and well data from the Upper Jurassic North Sea rift provides insights into the temporal evolution of fault-propagation folds in extensional settings. The hangingwall of the Oseberg fault zone is characterised by an asymmetric, fault-parallel syncline interpreted as the hangingwall portion of a breached monocline which formed in response to an upwardly-propagating normal fault. During the early stage of fault-tip propagation, a growth monocline developed at the depositional surface, resulting in early syn-rift units which thinned and onlapped towards the fault zone. Stratigraphic data from these early syn-rift units suggest that this initial phase of growth folding lasted ca. 19 Myr. Late syn-rift units formed an overall faultward expanding wedge, suggesting it was deposited after monocline breaching and a more typical half-graben basin had established. The results of this study have important implications for the timescale over which fault-propagation folds evolve prior to breaching and the impact of fault-propagation folding on the sequence stratigraphy of syn-rift successions.