BobGeo 2009. Days 4 and 5 at sea

Sunday 18th October

Jean-Francois is very keen to have the blog translated into French so that the families of the the people on board can read about what is going on during the cruise.
Success with Calypso (the carottier/corer): a 23 metre core is recovered.Yes, it is really Sunday this time! Because of problems with connecting to the blog site at the start of the cruise I have been running one day behind and if you have been following the blogs you will have noticed that the dates and days have been slightly confused. Had it not been for an email from my wife telling me that it was Saturday and not Thursday when I had emailed her then I might not have noticed.

Vincent Guilbaud (left) and Mathieu Kerjean process the data

Trying to remember what happened the day before is also difficult as my memory is not as good as it used to be and maybe the patches I have been wearing to combat sea sickness do have a side effect on me after all. I have decided to bring the pages up-to-date so that I can report the events as they happen rather than a day later.

(L to R) Michel Cremer, David Menier, Jean Francois Bourillet and Jean-Yves Tous study the Chirp trace.

Not too much happened yesterday morning and spent some time down in computer room in level 3 where the Chirp, Seismic and Multibeam data is processed then plotted out in the various maps and charts. These are then used to determine where best to deploy the various pieces of equipment such as SCAMPI and Calypso.

The major event of the day was the deployment of the Calypso in the afternoon. The Calypso consists of a 14cm diameter metal pipe into which is placed a 12cm plastic liner with an inner diameter of 10cm. It is driven into the sea floor by a 3.2 tonne weight which can push it down into the sediment by as much as 35 meters.

Laure Salzat calculates when the piston cable is released

A simple diagram of the bung inside the liner

A bung/piston placed at the bottom of the liner is attached to a cable that comes up inside the plastic liner, when the point of the corer touches the sea floor a mechanism then releases the cable which then maintains the bung up inside the liner that goes down like a piston creating a vacuum. This acts like a syringe and as the corer goes deeper into the sediment and as the bung is pulled upwards the vacuum it creates helps to draw up the core of sediment. The moment of the release of the bung/piston cable is quite critical and Laure Salzat has the task of trying to predict when the bung is released. There is also a non-return system which does not allow the sampled sediment to fall back out as it is brought to the surface.

Stage one of deployment

With the 3.2 tonne weight attached Calypso is now ready to be deployed.

After around 2 hours Calypso is retrieved and on first examination it looks to have been a successful deployment.

The end of Calypso covered in a very fine sediment

A very full liner being cleaned and dried before cutting it into one metre lengths to be stored and examined the following day.

Mathieu Kerjean labels the end caps before placing on the ends of each 1 metre length of liner

Sunday 18th October

It seems that I missed the party in the bar last night, as after dinner I went back to my cabin to see what could be done with the videos that I have been filming. From what I hear, it was a good evening and their were one or two tired looking faces this morning. I will remember this next Saturday.

After breakfast I headed for the laboratories on Level 3 to see if anything was happening and met Fabien Paquet busy examining the cores after they have been sliced lengthways.

Fabien recording the details section 11 from the core. This metre section came from around the middle of the 21.6 metre core that was collected last night.

If you look closely at the image on the left to where the arrow is pointing you can just see what appears to be a small fish shape. Fabien thinks that this mark may have been made by bioturbation many years ago. Bioturbation is the term used for the movement of sediment caused by the various animals that live and burrow there as the move around in the sediment.

This morning the box grab was deployed twice down to around 400 meters. Both time it failed to retrieve any sediment. This may have been due to the fact that the sea floor was a mixture of very fine sand and debris of corals.. It was decided to try with the other grab, I think it is called the swing-arm grab because of it method of operation. Unfortunately, it too was unable to penetrate the hard sand below so we will move to another location tomorrow to try again.

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