Expedition to the Mariana forearc

Mar. 23 - May 4, 2003

Day 31, April 22nd

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Day 31 Lost and Found

Well before sunrise, Jason is back on deck and the scientists are in the lab discussing the upcoming, and final, core at Celestial Seamount. Matt H. comes into the lab with a grin on his face and a twinkle in his eye, “You know that piece we lost last night from Jason’s manipulator?” He holds up a small piece of metal and says, “It looks just like this!” Peter was trying to pull out Jason’s sample tray which seemed to be stuck. Will got a flashlight to investigate and found the missing part stuck between the tray and the roller mechanism. The Jason Team had the manipulator back in operation in short order.

We have poked a lot of holes in Celestial Seamount looking for evidence of recent mud flow. In the early morning hours we send down a piston core, the 5th core at Celestial during this trip. A core taken in 1997 brought back a short sample of serpentine mud indicating recent activity but we haven’t found action at Celestial on this trip. The piston core was brought on deck at sunrise and held a nice sample of brown sediments but no serpentine mud. Each core tells the scientists a little more about the seamount, but this trip, on Celestial, we have not found evidence of recent activity.
Walk in science freezer Walk in science freezer
We pick up the transponders from Celestial and head south to Blue Moon Seamount. By sunset we are again setting transponders in preparation to deploy a break-away core and launch Jason for visual exploration.
Terra in Antarctic attire Terra in Antarctic attire

I was taking a shortcut through the cleaning supply room to get to the computer room. The short cut is really a bit longer but I can avoid the opening of 2 doors in the hallway. All these door knobs are giving me sore thumbs. The cleaning supply room is also the access to the walk-in refrigerator and freezer for science (not food). As I passed through, Sam and Terra came out of the freezer. They were better dressed for an Antarctic expedition than this journey in the tropics (the freezer is kept at a steady 4 degrees Celsius).

Sam is a grad student studying rare-earth elements and transition metals in the pore water of the sediments and serpentine mud of the mud volcanoes. Sam takes some of the push cores that Jason collects directly to the freezer. The elements he studies become highly reactive as the temperature increases and will react with other elements in the mud. The cores are easily contaminated when exposed to air so Sam works only with the push cores which can be kept sealed until they reach the freezer.

Sam working in the nitrogen environment (bag) Sam working in the nitrogen environment (bag)

The rare-earth elements in the pore water also react with oxygen when they are exposed to air. In the freezer, Sam and Terra put their samples in large plastic bags and inflate the bags with nitrogen that is less reactive than oxygen. There are gloves built into the bags so they can insert their hands and work with the samples. The whole scene looks like something out of a science fiction movie but this is for real.

Sam is looking at concentrations of about 9 transition elements, all the rare-earth elements and uranium. These have never been studied in a mud volcano environment and will give new knowledge about the geochemistry of subduction.

It takes Sam and Terra 4 hours to process 4 push cores. They still haven’t analyzed the water for the presence of the elements—they will do that back on land using an icp-ms (inductively coupled plasma mass spectrometer).

The air conditioning on this ship is very effective. I’m glad I don’t work in the freezer.

Science Summary - Day 31, April 22nd

Science Objectives, Day 31:

The thirty-first day of the cruise, Apr. 22, we prepared for a piston core, but were able to launch Jason2/Medea early in the morning. We will explore the summit scarps on Celestial Seamount, examine the piston core hole and search for signs of recent eruptive activity in the hollowed-out summit region of the seamount. The lowering will take all day.

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