JC010: Mud volcanoes and submarine canyons


Cruise diary

Day 7: Friday 18 May 2007
Position: Long 35º, Lat 6º, bearing 24º
Weather: sunny and very calm

Eduard writes:

"We are still investigating the Mercator mud volcano. Tomorrow we will go to explore another mud volcano: the Darwin, a little but deeper one that is about 50 miles away from the shore. I have just come from the Main Lab. I have been working with Katja sampling the core that came up this morning. It was not a core like the others that I have seen before - it was a ‘square shaped’ core (see photos below). This kind of core has thin walls. It is easier to push the core in the seabed -because there is much less resistance- and you can get a large volume of sediment. Whilst getting my hands dirty, I realised that this doughy and cold mud stuff I am holding is ideal to make a perfect bullet-ball to start a Mud War on board. I was just thinking about it, of course. After work, I washed my hands twice - today’s mud was really smelly because of all the hydrogen sulphide that the mud contains. This chemical compound is easy to recognise because it smells like a decomposed egg. And a decomposed egg smells very bad, doesn’t it?  Please, do not try it at home! I can see some of you hiding eggs under the sofas and wait and let them rot just to check that out.

Mixed with the mud, you can find surprises. Today we have found some fragments of rocks (see photos below). Phil has been identifying each kind of rocks with a microscope, and Ana has been helping me to make photos of the magnification. Andrey, an expert geologist, showed me a typical crystal that you can find in the Mercator Mud Volcano: a crystal of gypsum (calcium sulphate) mixed with natural salts (Sodium chloride and others).

Where do these fragments of rocks come from? The mud volcano brought them from deeper layers (few kilometres down!) and this morning they have been taken from a core sample, ready to analyse. Amazing, isn’t it?

These days, every time I can, I go to see a core going down. I see that sediment core is a tool that man can use to try and understand more and more about the Earth. I hope that tool is useful for preserving it..."

Examining the core as it arrives on deck

Rock fragments found amongst the deep-sea mud

Phil working the microscope

Gypsum crystals found at Mercator mud volcano

Gillian writes:

"The ROV camera revealed some interesting things last night and today. We are hoping to edit some of the tapes for you soon, so you can to look at it for yourselves. Isis produces hours of tape which are carefully labelled and kept for study back on land. The ROV brought up a sponge for study yesterday from 365m. In it there was a tiny crab about 5mm diameter. We took a photograph of it down the microscope as you can see.

I went into the radioactive lab where John and Barry were injecting radioactive isotopes into the bacteria collected yesterday. They will now incubate them to see how these isotopes are used by the bacteria. Also today I had a spell in the CT Lab (controlled temperature) helping Katja with the samples from the megacore. At 4ºC my hands were soon stiff with cold and I had to run them under the warm tap to thaw them out. When she then asked me to go out into the warm Moroccan sunshine to wash out all the cores for the next time round and I was happy to oblige!  The time out here is so precious as it is the only time cores can be taken with such specialist equipment. Making sure they are all carefully labelled is crucial. Imagine what would happen should they get mixed up: methodical, meticulous methods are all part of the job.

The Isis has just brought up some rocks encrusted with animals so I’m off to have a look..."

The crab - viewed down the microscope!

Rocks brought up by the ROV

Crinoids - sea lilies!

A sponge brought up from the depths

Hosing down the core containers

John and Barry busy in the radioactive lab

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