Expedition to the Mariana forearc

Mar. 23 - May 4, 2003

Day 10, April 1st

(click on any image for the larger version)

Day 10 PLAYING IN THE MUD

Yes, the maps are truly spectacular but… these sonar surveys take a long time. The initial survey of Big Blue Seamount took 28 hours. Add to that the 16 hours of the single transect from the deep sea to the summit, and Big Blue took a total of 44 hours.

Lifting the core liner Lifting the core liner over the side-rails onto the ship
 Today was the most fun yet. I finally got to play rather than just observe. We did a piston core. You can read about the differences between a gravity core and a piston core in the Cruise Info section, but it’s enough to know that with a piston core, we can get MORE MUD! This time we got 14 core-feet of blue mud. Since the piston core takes a longer sample, more bodies are needed to lift it onto the ship. I put on a hard hat and lifevest and added my muscle to the endeavor. Whenever we are working near the ship’s side-rails, we must wear lifevests and when we work under the cranes, we wear hardhats. I much prefer to be a part of the action.
When the core pipe is brought to the surface, the crane lifts the pipe to a horizontal position along the side-rails of ship. From there on it’s manpower. Before removing the plastic core liner and bringing it onto the ship, the core cutter is removed. The core cutter is a heavy, 12-inch section of stainless that sits on the end of the core pipe. Today, as they were removing the core cutter, it shot off the end, 10 feet over the water, and sank in 4000 feet of water. Not only is there mud and water in the core sample, but gas too (carbon dioxide and methane). At the surface it’s warmer and there is less pressure so the gas expands, and boom… there goes the core cutter. This little item is worth hundreds of dollars. Chris. M., the core specialist, has already been in the machine shop modifying the replacement core cutter so this won’t happen again. I thought the explosive shot of the core cutter was fun stuff but Chris didn’t like my choice of adjectives.
Then I got to play with the chemists in the blue mud. All I did was put mud into the centrifuge bottles but I had fun and got muddy too. Some of the pore water tests are conducted right here on the ship. Geoff, Mike and Sam are testing the pH, alkalinity, chlorinity, total carbon dioxide, and sulfide and calcium content. Back on land, they will test for most other elements and their isotopes. The complete chemical analysis will take about a year. Geoff and Mike are authorities on pore water chemistry and Sam is working on his Masters Degree.
long blue core Long blue core
filling centrifuge bottles with blue mud Filling centrifuge bottles with blue mud

I was talking to Geoff as he ran titrations to determine the alkalinity of the pore water. The titration equipment used to be in the main lab but it’s so cold in the lab that the equipment didn’t work properly. The titration equipment now sits on the table in the office where I work, between the computer and the copy machine. Perfect, I can watch and ask questions as I write.

From the chemical analyses, the scientists learn about the changes in the Pacific Plate as it is subducted. As the plate is first subducted, it is compacted and pore water is squeezed out. None of this initial pore water has been collected. Deeper pore water has been studied. As the plate goes deeper, the temperature and pressure increase: the pore water has low alkalinity and high calcium. As the plate goes even deeper and the temperature and pressure increase further: the pore water has high alkalinity and low calcium. We can study what is happening in the deeper parts of the subducted plate because the mud from the mud volcanoes is bringing the evidence nearer to the surface in the pore water.
taking samples to study microbes Titration equipment for chemical tests

On the board: Mandatory today, fire prevention movie at 1330. but All the scientists are playing with the mud. So much for MANDATORY.

Today is April 1. The nature of April first went right by me. I was having too much fun with the blue mud to even notice, but you need to be sure and read the science objectives for today.

Science Summary - Day 10, April 1st

Science Objectives, Day 10:

The tenth day of the cruise, beginning the month in style, will be spent luxuriating in the sun on deck in lounge chairs, sipping ice tea with lemon wedges and fresh mint sprigs, and later a sumptuous feast of fresh mahi mahi caught off the fan tail, barbequed to perfection under a spectacular tropical sunset. Afterward, there will be dancing in the Main Hall and live entertainment from some of the most highly acclaimed talents known today.

Ok, ok, so it’s April first and what we’ll really be doing is a piston core, a much more complicated coring procedure than our previous gravity coring. It will probably net us close to 20 feet of extremely dense and very heavy serpentine mud that we will have to haul in from over the starboard side rail in 10-foot lengths, saw in half in the staging bay and then man-handle around the “rabbit warren” of vans on the afterdeck into the Main “Hall” (errr, I mean “Lab”), where it will be sampled for pore waters every foot or so, by several scientists elbowing one another for access before the mud warms up so much that the pore fluids start reacting. If you don’t think that takes fancy dancing, you haven’t tried it. It is pretty entertaining watching the scramble to get the centrifuge tubes filled, cooled, spun, and the pore fluids siphoned off, titrated and electroded in non-stop action for hours on end. No wonder these guys have such highly-acclaimed reputations. The DSL-120 system will have several boards swapped out by the Jason2 group and transponders used at the last survey site will be picked up while the scientists are doing their thing in the Main Lab. The DSL-120 system will be tested once the new boards are in place. And what about that sumptuous meal? Well, actually most of the scientists and DSL-120 engineers will work through lunch, so it’ll be sandwiches when they can grab a minute. We will all make the assumption that the sun actually did set, as nobody will have time to go check to see. Then we will wrap and store the core sections and clean up the Main Lab as we head off for an all-nighter survey with the EM300 system over the next two target sites.

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