Juan de Fuca Ridge Cruise
July 20 - August 1, 2000
Over 650 km (~400 miles) off the Washington-Oregon Coast
Logbook
July 21: Day #2
Log Entry: Good Morning from the mid-ocean ridge!
6:00 am: We have arrived on site, a full 6 hours earlier than expected. We are above the beginning point of our first dive, at the southern portion of the Cleft segment of the Juan de Fuca ridge, some 300 km (~200 miles) from Newport, Oregon where we left yesterday morning. If all goes as planned, we will be returning to the surface with 4 rock cores taken from the new coring sled on Tiburon, as well as six wax core samples taken using Tiburon's mechanical arm. We should be dropping Dr. Mike Perfit's rock corer off the stern of the ship after the dive is complete, and will be looking at the glass samples collected.
As I explained briefly yesterday, we all received a quick lesson from Dr. Michael Perfit on how to load, unload, and reload his rock coring device, since he will need help handling the samples when they are brought on deck. The device will be released from the back of the ship, independent of the ROV Tiburon. The rock corer is a 270 kg (600 pound) device which travels to the sea floor down a cable at a speed of 50-100 meters/second. At the base of the device are small, metal pipe-fittings which are loaded with wax (surf wax, actually!). When the device strikes the bottom of the ocean, it shatters the surface of the volcanic rock, which is composed of a glass material which forms when the hot mantle material rapidly cools upon contact with the cold ocean water. The small glass particles, sometimes only as big as a grain of sand, stick to the wax, and are brought to the surface. The wax is then scraped out, separated from the sample in the microwave oven, and then initially analyzed under a microscope. This first analysis of the glass can give a relative age, based on its surface quality. Glass that has been in the ocean for a very long time appears "dirty", usually due to the accumulation of manganese deposits on its surface. Glass from recent volcanic flows, on the other hand, appears shiny and clean, free of deposits. Once back in his lab, Dr. Perfit can perform two more tests on the glass, which will give more specific evidence as to the origin of the glass. First he uses an electron microprobe on the sample, which fires electrons onto the surface of the glass, and receives back a unique x-ray signature, revealing the presence of major elements in the sample. A second test involving a laser can detect trace elements in the sample. These tests give a "genetic fingerprint" for the glass, letting scientists know where in the mantle the lava flow originated from. With a simple wax-coring device, scientists can use a very small sample of material to learn a large amount about the origins of the lava flows which created the ocean floor.
The sun is just about to rise over the clouds on the eastern horizon, and the crew is readying the ROV for the dive. As one stands on the deck, there is nothing but water for kilometers around topped by a beautiful sunrise. A potentially lonely spot on the earth, this place is buzzing with the excited anticipation of all involved.
Dive Report: Dive #175
We arrived at our dive site at 6:00 am this morning, and the vehicle was cleared to dive at 14:03 GMT, or 7:03 am Pacific time. Tiburon descended to a depth of 3,298 meters. We traveled up to the top of a ridge, which transects the transform zone. This area appeared to be the trace of a fault based on our observations of the seafloor which showed the scars of tectonic movement. We found a surprising amount of fauna on the bottom sediment, including brittle stars, sponges, crinoids, and what appeared to be the remnants of an old tube worm. The bottom appeared to be small broken pieces of talus which was poorly sorted: big pieces mixed with smaller pieces. We took a few samples of both biological fauna as well as our geological samples. We took one rock core, which took about 20 minutes to extract, and all of the coring sled functions were working properly. Sadly, we did run into a communications problem between the coring sled and the vehicle Tiburon which caused the vehicle to lose all hydraulics. After the problem occurred more than once, we realized that it was something that might hinder further use of the sled on this cruise. Although we are in communication with engineers back at MBARI and are working on a short-term solution, we may be forced to remove the sled from the vehicle and switch to the benthic sampling sled until the problem is resolved. Making creative solutions to problems encountered at sea when resources are limited is one of the challenges that we face, and one of the realities of ocean research.
After the dive ended some 10 hours after it started, we immediately proceeded to the rear of the ship to begin taking wax cores with Mike Perfit's coring device from Woods Hole Oceanographic Institution. We performed wax coring until around 6 am on the morning of the 22nd, when we stopped and immediately began our 2nd dive with Tiburon. Research at sea doesn't leave much time for anything other than research, not even sleep at times! Here is one of our 2 rotations that, if aboard the Western Flyer, you would have to follow:
On from 3 am - 12 noon; off from noon until 6 pm; on from 6 pm - 9 pm; and then off from 9 pm to 3 am when it all starts again.
Often a researcher will have other work that needs finishing up, and that work can be done between shifts. Last night, for example, some of our researchers only had time to grab 2 or 3 hours of sleep between shifts, and sometimes, those hours come in the middle of the afternoon!
Today's Menu
Breakfast:
Chilled fruit
Oatmeal with raisins and brown sugar
Eggs to order
Omelets: ham, mushroom, bell pepper, cheese, onion
Hash browns
Creamed beef
Pancakes: peach pancakes
Lunch:
Spinach salad with peanut dressing
Fruit salad
Split pea with ham soup
Pot stickers
Veggie egg rolls
Shrimp stir fry vegetables with rice
Dinner:
Salad bar
Split pea soup
Chef French's BBQ teriyaki chicken
Green beans
Mashed potatoes and gravy
Uncle Dave's garlic bread
White chocolate raspberry cheesecake