Submarine geomorphology and geology of the Mississippi River Delta front

Vita.Integrated high resolution seismic, side scan sonar and engineering borehole data were used towards an interpretation of the shallow seismic stratigraphy and geomorphology of the Mississippi River Delta Front. Three seismic stratigraphy and geomorphology of the Mississippi River Delta Front. Three seismic stratigraphic groups have revealed the transgressive-regressive depositional sequences associated with Late Pleistocene glacio-eustatic changes in sea level. Each of the stratigraphic groups was found to consist in a lower clayey unit and an upper fine sand and shell unit. Paleo-topographic maps of the stratigraphic units reveal the morphology of the former continental shelves. Structural features observed within the delta front area include shelf edge growth faults, a salt diaper and an extensive erosional unconformity which is believed to be the result of a large slide mass of early Holocene age. The modern prodeltaic sedimentary wedge includes up to 100 meters of very soft, highly underconsolidated gas bearing silty clays, deposited during the past 500 years. The thickness of this unit within the delta front area has been mapped. The submarine morphology of the delta front reveals features associated with mass movements which are similar to subareai mud slides and debris flows. The observed features include collapse depressions, bottle-neck slides, mud flow gullies and depositional toe lobes. These features have been mapped within the delta front region. The downslope movement of sediments by mass movement appears to represent an important process of sedimentary transport. Mechanisms responsible for the observed mass movements include gravitational forces acting upon low angle slopes, high rates of sedimentation and the in situ generation of biogenic gas which have produced excess pore pressures, low shear strengths and low effective stresses