Investigation of the interaction between salt movement, faulting and deposition, using high-resolution 3-D seismic data; Eugene Island South Addition, Gulf of Mexico



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Deformation on the Louisiana shelf results from the complex interaction between salt movement, faulting, and deposition. The goal of this study is to investigate the relationship between these processes through detailed structural interpretation of data from Eugene Island South Addition, Gulf of Mexico. I used a high-resolution 3D seismic dataset that is an approximately 1850km^2 seismic survey acquired by Petroleum Geo-Services in 1995-1996. The seismic data were processed through Kirchhoff prestack time migration. I interpreted the fault systems, sedimentary bodies, and salt geometries based on 3D seismic data, well data, and previous studies in adjacent areas. I calculated the displacement-length values based on the faults and horizons interpretations. Fault displacement-length data were used to evaluate the pattern of deformation and how it evolved. I used 29 publically available wells to convert the 3D time data to depth. I interpreted 31 faults and 10 horizons. The fault systems in the study area consist of 25 concave basinward normal faults. Most of the faults sole into salt, a salt weld, or a salt roller. I show that most normal faults were active during the Pleistocene (0.46-0.65 Ma) based on the age of growth strata in their hanging walls. This implies that salt movement and fault displacement are contemporaneous with sedimentation. Strain analysis of the fault system shows that extension is primarily accommodated by the major faults which include fault 1, fault 2 and fault 2-e located in the central part of the study area. My results show the location of kinematically linked faults. Fault 1 consists of at least three major linked faults. Fault linkage along fault 1 is observed along strike and in the dip direction. Fault 2 and fault 2-e are linked by fault 2-d. D*L plots show that fault 2 is linked to several smaller faults. Fault 2-e consists of at least two major segments that grew by lengthening until they overlapped and subsequently linked. My research shows that faults in the study area are kinematically linked and act as a system which accommodates Pliocene and Pleistocene extensional strata that were deposited in mostly north-south-oriented basins. Since most of the faults in the study area sole into salt, it implies that the kinematics of salt deformation are the same or at least similar to the kinematics of faulting.



Structural interpretation, Seismic, Kinematics of salt deformation, Kinematics of faulting