STRUCTURE OF THE NORTHERN MARGIN OF THE TERREBONNE TROUGH, SOUTHEASTERN LOUISIANA: IMPLICATIONS FOR SALT WITHDRAWAL AND MIOCENE TO HOLOCENE FAULT ACTIVITY

The aim of this study is to understand the fault architecture of the northern margin of Terrebonne Trough, which is a Miocene and younger salt withdrawal basin lying within the subsurface of southeastern Louisiana. The study area is located in Terrebonne parish, and our dataset includes a 3-D seismic reflection volume, well logs and biostratigraphic data. The faults in the study area were initiated by salt movement and show continued activity through the Pleistocene. Previous studies based largely on 2-D data interpreted the orientation of the faults as mainly E–W striking, similar to the strike of the Golden Meadow fault, an important fault along the basin’s northern margin. However, interpretation based on the 3-D seismic volume and well logs illustrates that the structural style is not that simple. A NW–SE striking fault population is also important and is interpreted to be largely coeval with many of the E-W striking faults. The E–W striking faults are normal and dip towards the south whereas the NW-striking faults are normal and dip toward the southwest. The three largest faults within our study area – the Golden Meadow fault, another E-W striking fault known as the Montegut fault, and the NW-striking Lake Boudreaux fault - are continuous to the top of the 3-D seismic volume and correlate with areas of recent coastal subsidence and land loss.