A new journal article led by Dr. Derek Sawyer published in Scientific Reports describes extremely large-amplitude waves that can be generated in hypersaline seafloor brine pools by the impact forces of submarine landslides.
Subsea hypersaline anoxic brine pools are among the most extreme habitable environments on Earth that offer clues to life on other planets. The hypersaline brine is too salty and anoxic to support all but extremophiles. The anoxic and abiotic conditions are favorable for outstanding preservation of sedimentary layers and organics, which makes them well-suited for paleoceanographic studies.
However, while brine pools are often assumed to be quiescent and stably stratified environments, our work describes how the impact forces of underwater landslides can cause significant disturbances of the brine as well as inject mass gravity flows into the sedimentary basin to disrupt the otherwise simple stratigraphy.
This study uses high-resolution seafloor bathymetry and three-dimensional seismic data to image the subsurface geology in the southern half of the Orca Basin in the deepwater Gulf of Mexico. Orca is one of the largest known brine pools in the world and is up to 220 meters deep, approximately 8,000 years old, and was discovered in the mid-1970s. Since its discovery, the Orca Basin, has been the site of important paleoceanographic studies, microbiological, geochemical, and a deep sea drilling program.
We use geophysical data that reveal large landslide scarps that lie hundreds of meters above the brine pool with debris and blocky deposits lying at the bottom of the brine pool (Figure 1). We describe the large-scale disruption to the brine pool that results from submarine landslides impacting the brine pool. Submarine landslides are capable of generating waves with amplitudes on the order of 200 meters, which rival the largest known ocean waves. A vigorous mixing will occur that will introduce significant amounts of oxygen, sediment, and organic matter to the brine pool system. The wave heights could exceed the confinement of their basins thereby spreading hypersaline brines to surrounding topographic lows. Landslides and their impact waves will greatly affect the physical structure of the biological community that are typically observed living at the edges and above brine pools.