Exploring >40 m Tall Active Black Smokers
Tuesday, August 30, 2011
A Major Discovery at Axial Seamount
Sulfide blocks the size of small cars at the base of the > 40 m tall sulfide edifice provide hints of active hydrothermal sites above.
Blocks of Massive Sulfide at New Field
Today was the final ROPOS dive of the series, ending with an exciting dive in the new hydrothermal field discovered at the beginning of Leg 2. The main goal was to inspect the primary cable laid in this area, but once that was accomplished there was time for exploration of this fantastic place. It is unusual because it is at a water depth of ~ 1900 m, far down the flank of Axial Seamount. It is also unusual because it contains huge sulfide structures rising >40 m above the surrounding seafloor. Many of the structures are extinct, but the largest one has numerous active chimneys, flanges, and sites of diffuse flow. It is a monolith, marked at its base by extensive talus slopes of massive sulfide blocks, some the size of cars.
Midway through the dive, University of Washington graduate students Alden Denny and Monica Riess were given the “hot seat” to continue exploration of the field, and they did a fine job of working with the pilots to direct them to places never before seen. Along the route planned by Alden, they drove over numerous large pillow mounds, but also came upon three other sites of hydrothermal deposits with a total of two large structures active and two that were extinct. Around 1400h PDT the dive ended and ROPOS left for the 1.5 hour drive to the surface. It was a great way to end the VISIONS’11 dive series. It is not often we are lucky to make such discoveries – a team effort all around.