Seismic Evidence for Subsurface Sediment Remobilization and Fluid Flow Systems in Vema Dome Area of Vøring Basin, Offshore Mid Norway

Abstract

Manifestations of subsurface fluid flow take a variety of forms in the Vøring Basin as revealed by high resolution 3D seismic analysis. Enigmatic ooze mounds linked to soft sediment remobilization measuring up to 74m high has significantly modified the seafloor over the Vema Dome in contrast to the relatively undisturbed seafloor over the adjacent Nyk High area. Detailed analysis of these gigantic mounds in terms of geometry, spatial distribution, seismic character and stratigraphic relationship to other fluid flow features sheds more light on the possible trigger(s) of subsurface sediment remobilization in the Vema Dome. Further structural consequences of sediment remobilization in the study area are evident in the development of craters, ridge and trough-like structures. The spatial correlation between the exposed and buried mounds, fluid flow features and an underlying igneous sill complex suggest a link between the processes that structurally modify the Vema Dome seafloor. A conceptual model describing the interrelationship between mounds, sill intrusions and fluid pathways is presented in this study. The model links mound and pockmark formation to upward and lateral transport of hydrocarbon-rich subsurface fluids through conduits such as pipes and hydrothermal vents within the study area. Whilst several authors such as Hovland et al., 1998 and Hjelstuen et al., 1997 have described sediment remobilization at different stratigraphic levels within the Cenozoic succession in the Vøring Basin and linked the mounds to fluid venting and active shale diapirism, little or no work has focused on a detailed description of the mounds above the Vema Dome, their role in geohazard assessment and the implications for petroleum systems. This clearly reveals the regional significance of this study in understanding subsurface sediment remobilization and petroleum systems in sedimentary basins.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018