Temporal constraints on the growth and decay of large-scale mobilized mud masses and implications for fluid flow mapping in sedimentary basins

Seismic-stratigraphic analysis of the Cretaceous to succession of the Uer Terrace, North Sea seabed Basin, Norway, demonstrates that the Upper Oligocene succession has undergone large-scale mobilization of mudstone-dominated units due to the upward migration of water and associated hydrocarbons into the interval, which is in some way linked to a period of gas expulsion from adjacent deep basins. Seismic-stratigraphic analysis of units overlying the mobilized zones indicates they created positive seafloor topography during the Late Miocene implying gaseous fluids were expelled at the seabed. Loading by the overlying Pliocene succession caused the mobilized mud masses to deflate and resulted in the formation of low-relief, fault-bounded craters. The results of this study have implications for understanding the location and timing of fluid flow in sedimentary basins.