This week’s Sea-Floor Sunday is an image from the continental slope in the northern Gulf of Mexico.
The image is from a short article on USGS’s website called Mapping Turbidite System Pathways on the Louisiana Continental Slope with GLORIA and Multibeam Bathymetry. The GLORIA (Geological LOng-Range Inclined Asdic) tool is a side-scan sonar tool that produces images showing varying intensity or ‘backscatter’ that represent textural characteristics of the seafloor (read more about the GLORIA tool here).
The image below is the multibeam bathymetry showing the seafloor topography. The length of this map (from top to bottom) is approximately 100 miles (for regional context, see this map). The circular to oval features are called salt-withdrawal minibasins. Jurassic salt deep in the subsurface has ‘flowed’ upwards over geologic time creating domes, diapirs, ridges, and so on. Sedimentation has occurred and interacted with this process.
The colored lines denote the pathways for turbidite systems that have developed across this complex topography. An interesting feedback has developed such that the low spots (the minibasins) trap sediment, which increases subsidence, which in turn promotes further salt withdrawal underneath the basin, which in turn creates a low spot on the seafloor. Some of these minibasins have several thousands of feet of structural relief along their flanks. Check out the original USGS article for more information.
Also check out this post from Nov 2007 for more images of the Gulf of Mexico continental slope.