West Coast Expedition
July 20 - August 30, 2002
West Coast of North America

August 22, 2002: Day #34

Figure 1 is the deployment of the low-velocity flow meter in an area of shimmering diffusive flow. The upright component in the back is placed on top of the venting. The horizontal cylindrical component is the datalogger. Both components, connected by a two meter long cable, were carried down on the front porch of the vehicle. They were lifted into place by the manipulator using the yellow nylon handle. At the end of the dive, both components were loaded into the second elevator run of the day and sent safely back to the ship.

Debra Stakes writes: Today’s dive focused on instrument deployments and geology in the Main Endeavour hydrothermal field of the Juan de Fuca Ridge. This would be our second dive in the Main Endeavour Field and would require the ROV and elevators to transport three separate sensors and their attached data-loggers safely to and from the seafloor. The data collected by these sensors is diverse, and is representative of the types of continuous, long-term environmental measurements required to constrain episodic seafloor processes. In-situ sensor packages included a flow meter, temperature-resistivity probe and microbial incubator. One of the goals of the Keck-supported effort is to develop new sensors and new installation methods to enable continuous measurements to be made over months or years.

Two of the sensor packages were carried down on the ROV itself, and deployed. After Wednesday’s dive, the coring sled was replaced by the benthic toolsled that includes a drawer to hold both samples and instruments. The benthic toolsled also has an expansive front porch where bulky items can be secured for transit through the water column. The first instrument carried down on the front porch and deployed by the ROV was a prototype flow meter for diffusive flow sites such as patches of chemosynthetic tubeworms. The flow meter itself stands upright and is attached by a short cable to the cylindrical datalogger (Fig. 1). The vehicle also carried down a prototype borehole incubator that will be placed into a hole drilled into the black smoker known as "Smoke and Mirrors" (Fig. 2)

The third sensor was carried down on the elevator with a biobox for collecting samples (Fig. 3). This elevator was then carried by the ROV to Smoke and Mirrors to deploy the sensor and collect tubeworms from near the top of the edifice (Figs 4 and 5). The dive was completed with a geological sampling traverse across the center of the axial valley (Fig. 7).

Figure 2 captures the attempted emplacement of the borehole incubator on Smoke and Mirrors. A relatively thick coating of sulfide sediment in this area, prevented insertion of the minicork.

Figure 3 shows the first elevator delivery to the seafloor for this dive. On one side is the gray plastic "biobox" that would be filled with tubeworms. The resistivity sensor rides down in the other compartment. A large spider crab decides to inspect the contents of the elevator soon after its arrival.

Figure 4 is a healthy bush of chemosynthetic Vestimentiferan tubeworms observed at one of the sulfide edifices.

Figure 5. After documenting changes in the sulfide structure, samples of the tubeworms were collected and put into the elevator biobox for an express ride back to the ship.

Figure 6. Set of new sulfide spires provide a challenge for the ROV pilots to gather temperature data and fluid samples. The fluids at this site were >370°C. The filled gas-tight fluid samplers were sent back to the ship in the elevator.

Figure 7. Tiburon examines geological samples during a geological traverse under the watchful eye of a large spider crab


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