West Coast Expedition
July 20 - August 30, 2002
West Coast of North America
August 7th, 2002: Day #19
Debra Stakes writes: Our dive plan for today (Dive T458) was to survey the Vent 1 area of the southern Juan de Fuca Ridge. This hydrothermal area has "black smokers" made of metal sulfides spewing fluids with temperatures up to 275 C. In 2000, we could find only one really robustly active smoker - the rest were all dormant. Today would prove to be different. The pilots landed the vehicle right at the vent site and pilot Paul Tucker found a smoker in less than 20 minutes. It was about 5 meters tall and surrounded by smaller spires that made parking a real problem. While we looked for an orifice near the base of the structure, we bumped into another structure behind us. After getting engulfed in a snowstorm of tubeworms and smoke, we discovered the real Vent 1 chimney covered with tubeworms and really pouring out the fluid.
We wanted to get a piece of sulfide into the biobox, but it was on the wrong side. We tried everything including using the thermocouple probe to bat the sulfide into the drawer. Nothing worked and we ran out of time. The pilots worked hard to find a sampling site were we could collect fluids in out bottles. We eventually only collected fluids in the smallest bottles rather than risk having the ICL-control electronics fry in the hot fluids. We learned a lot today but only have a few samples from the vent area to show for this.
A blown hydraulic hose forced us to recover the vehicle. We took the opportunity to remove all of the water bottles and extra equipment before descending on dive T459 to collect rocks samples from the eastern side of the ridge. Here we found beautiful glassy lavas with an assortment of drainback features. We also found another area where low temperature fluids have reduced some of the igneous rocks to rusty piles of mud.
New technology for sampling submarine hot springs. Submitted by Dr. Peter Saccocia, Associate Professor of Earth Science, Bridgewater State College, Bridgewater, MA
What distinguishes a geologist from an oceanographer? About 2000 meters of seawater. This is, of course, the reason why the seafloor remains mostly unexplored and why research in marine geology and geochemistry is such a challenge. For example, if you were to ask a land-based geochemist to measure the chemistry of the spectacular geysers at Yellowstone National Park, that scientist would probably say: "no problem, I’ll get you the results in a few days". The scientist would then travel to Yellowstone with a few clean bottles in hand, spend a night at a great campsite or lodge, and then saunter off to the nearest hot spring the next morning (passing a few bison along the way) to scoop up some water samples. No problem! Now put those hot springs on top of the earth’s biggest mountain belt, submerge them under 2000 meters of seawater, and ask the same question. I think the reply you receive (if you get one at all) would be quite different. Thankfully, over 25 years of research in marine technology and geochemistry has led to many innovative techniques to access and sample the spectacular hot springs that emanate from the seafloor along the global mid-ocean ridge system. These pioneering efforts have yielded an enormous amount of data on the chemistry of submarine hot springs. Today, scientists on-board MBARI’s Western Flyer are using the tethered undersea vehicle (Tiburon) to test yet another advance in the technology employed to sample active submarine hot springs that will further advance our knowledge of the chemistry of these systems. Dr. Meg Tivey and myself, together with the skilled Tiburon pilots and Chief Scientist Debra Stakes, have successfully deployed a new sampling device developed by Dr. Jeffrey Seewald, a collaborator of Dr. Stakes at the Woods Hole Oceanographic Institution. The primary advantage of this new approach is that hot water sampled on the seafloor (at pressures over 200 times the pressure at earth’s surface) can be held at that high pressure when the water sample is brought to the surface. Then, sub-samples of the hot spring fluid can be drawn out of the newly designed water bottles in the ship’s laboratory while maintaining seafloor pressure in the bottle. Accordingly, this new approach allows for the measurement of dissolved gases and a huge suite of volatile organic compounds, in addition to major and minor elements, all from the same water sample. Given the increasing amount of research on the microbiologic communities that live around submarine hot springs, and the provocative claim that life on earth may have originated in these environments, measuring the concentration of dissolved organic compounds in the hot springs will likely advance our knowledge of the complex interactions among hot rock, water, and life in this fascinating and complex submarine ecosystem.