Hot Site

Rich Viso here to update you on what is happening out here on the R/V Atlantis. The last couple of days have been quite interesting as we continue to hit our dive targets heading eastward. Right now we are in water depth of about 700 meters. The DSV Alvin is presently on the bottom with the chief scientist, Mandy Joye and Lisa Nigro from UNC Chapel Hill. They are collecting push cores at an active mud volcano called ‘Hot Site’. Many of the cores and some of the brine fluid that has been recovered so far contain large concentrations of hydrocarbons that are easily seen and have strong odors. These are natural hydrocarbon seeps, though later in the cruise, we will head nearer to the recent oil spill site for comparison.

The continental slope in the northern Gulf of Mexico is proving to be a really amazing place. Unfortunately we had rough weather for a couple of days and therefore missed a dive. During the rough weather though, we were treated to a spectacular display of flying fish being chased and eaten by a large pod of dolphins. The shear number of animals and the rough seas as a backdrop made this an impressive display that lasted throughout the entire night and into the morning.

Mapping the slope in the northern Gulf has been an interesting and challenging experience. We have seen water depths that vary between 400 and 2400 meters. The bathymetry is quite rugged in some places and the rapid changes pose some interesting challenges for the sonar equipment. This ship is extremely well equipped with a variety of sonar types to track instruments, map the seafloor, track the location of the submarine, and image the sediments layers beneath the seafloor. The image below is a photograph of a multibeam map on the computer screen. The field of view is about 15 kilometers across. Today, the Alvin is at a site located in the top center of this photo, on the ledge surrounding the large peak. The large dome-like peak is a typical feature for the seafloor in this area. The bathymetry is largely controlled by upward doming of salt layers from deep within the sediment record. Heat and pressure from the overlying sediments cause the salt to squeeze upward in daipirs that dome and fault the shallow sediment layers.

At this point on the ship there is increasing talk of the upcoming visit from a supply ship that will bring some items that the science party is running out of, as well as a few media personnel. After a few weeks at sea, it will be fun to have a couple of new faces aboard the ship.

Here are some links you might find interesting:
Ship position and track line history
Dr. Andreas Teske’s blog (UNC Chapel Hill)
Dr. Mandy Joye’s blog (UGA)
Field Note Event: