SALT-SEDIMENT INTERACTION, NORTHERN GREEN CANYON AND EWING BANK (OFFSHORE LOUISIANA), NORTHERN GULF-OF-MEXICO

Structural and sequence stratigraphic interpretations of two-dimension al seismic and well data from northern Green Canyon and Ewing Bank wer e integrated to evaluate how salt deformation influenced the distribut ion of Pliocene-Pleistocene facies in time and space. Two techniques w ere employed. First, twelve palinspastic maps of near-surface structur e were constructed, These were combined with maps of interpreted depos itional environments to show how shallow salt diapirism created bathym etric relief that influenced the configuration of sediment transport s ystems and depocenters through time. Second, tectonostratigraphic pack ages comprising multiple sequences were defined based on external geom etry, Different stacking patterns of these packages characterize four types of minibasins, each with a distinct history of salt evacuation f rom underlying salt stocks and sheets. Interpreted seismic facies were analyzed within this minibasin framework to evaluate how deep-salt wi thdrawal influenced the distribution of depositional systems. The resu lts show that both structural and sedimentological variables influence d lithofacies development. External factors dictated the volume and ty pe of systemwide elastic input. Regional factors, such as nearby salt structures and the position of deltas, controlled the dispersal of cla stics. Local factors, such as the thickness of underlying salt, influe nced minibasin-specific evolution. These factors interacted at three s cales: (1) a broad transition from sand-rich ponded settings to shale- dominated bypass settings during the Pliocene-Pleistocene, (2) fluctua tions over periods of several sequences that created highly variable s tratigraphic stacking patterns, and (3) a progression from ponded to b ypass facies within individual sea level cycles. Analysis of these var ious factors can improve the prediction of reservoir distribution with in slope minibasins, and thereby reduce the risk in subsalt and deep-w ater exploration.