SUBSIDENCE ALONG THE GOLDEN MEADOW FAULT IN SOUTHERN LOUISIANA

The Golden Meadow fault is a growth fault system that runs through coastal Louisiana, roughly parallel to the shoreline. Recent subsidence along the fault line in the area of Empire, La. has been documented on aerial photographs. It is important to determine how active this system is, and, if it is currently active, what influences that activity. This is relevant from the point of view of both short-term wetlands conservation and long term scientific evaluation of growth fault systems in general. Growth faults are gravity driven, syndepositional, normal faults. These faults have been studied extensively by the petroleum industry as they occur on heavily sediment loaded margins and can create hydrocarbon traps in both the footwall and in the “rollover” of the hanging wall. While the basic structure of these faults has been studied, much work is still needed on the kinematics, often complicated by allochthonous salt structures, and on the displacement patterns along strike. Displacement profiles can graphically express the state of interaction among fault segments that are not physically linked. In tectonically activated normal faults these individual segments respond to changes in the stress field around them as slip occurs on neighboring segments. The literature on growth faults has so far been focussed mostly on the displacement patterns down dip. To complement the work that has been done so far, we use aerial photographs, proprietary seismic data, core transects across the fault, carbon-14 dating of core samples, bathymetry transects, and plant succession and dieback observations, to construct displacement profiles and a history of the fault’s movement and segment interactions up to the present day. There appears to be significant Pleistocene displacement and Holocene displacement of at least one meter.