APPLICATION OF KINEMATIC SEQUENCE STRATIGRAPHY TO GROWTH STRATA ASSOCIATED WITH A LISTRIC GROWTH FAULT IN THE SOUTH MARSH ISLAND REGION, OFFSHORE LOUISIANA

Using a new stratigraphic-mapping method--kinematic sequence stratigraphy--the geometry and stacking patterns of Miocene growth strata associated with a listric normal fault are analyzed in 3D seismic data in the South Marsh Island region of offshore Louisiana. These growth strata are associated with a landward dipping, listric normal fault common to the northern Gulf of Mexico that are interpreted to result from salt evacuation driven by differential sediment loading. Growth strata in seismic reflection data of the South Marsh Island are identified by (a) stratal thinning onto the crest of a rollover anticline, (b) fanning dips of units towards the listric normal fault, and/or (c) up-section decreases in structural dip. These growth strata are subdivided into seven kinematic sequences by kinematic sequence boundaries that are local tectonically driven angular unconformities. Internal structures of each kinematic sequence display onlapping and overlapping followed by offlapping stratal terminations, defining onlap, overlap and offlap kinematic domains. These subdivisions represent relative balances between the sedimentation and hangingwall block uplift/subsidence rates. Seismic facies analyzed by seismic parameters indicate that kinematic sequences are dominated by slump deposits, prograding wedges and deltaic fans. Isopach maps for each kinematic sequence indicate that the largest accommodation matches the largest fault displacement. Along fault strike, geometry of fanning dip and thinning in kinematic sequence attenuated northward and become conformable at the northern end of the fault, indicating a clockwise rotation of fault block. Along fault strike, variations in geometry and thickness of kinematic sequences are explained by (1) sedimentation rate relative to fault slip rate, (2) change of accommodation caused by hangingwall block subsidence, (3) clockwise-rotation of fault block. The preliminary study suggests that kinematic sequence stratigraphy can constrain interaction of structural and sedimentary processes in growth strata associated with a listric normal fault, and can be used for analysis of stratigraphic facies influenced by structural deformation.