JC010: Mud volcanoes and submarine canyons


 JC10



Cruise diary


Day 15: Saturday 16 June 2007
Position: 39° 30.9457N, 09° 39.606W, Nazare Canyon
Weather: Overcast all day with some showers and light to moderate seas


Helen writes:

"I’m not sure where today’s gone. It’s flown by. Having spent the early part of the morning in the ROV van, photographing some interesting rocks and the occasional gorgonian or sea star, Isis came back to the surface at 7am. So, it was back to bed for an extra couple of hours sleep. As it's Saturday, the Captain makes checks on the galley, communal areas and cabins, so I made sure that my cabin was tidy and my sink & floor clean.

After lunch (braised liver & sausages with mashed potato), I started splitting cores with Raquel and Veerle. The 12 and 21 metre piston cores that were sent down a couple of nights ago were initially cut into smaller lengths. We spent a few hours this afternoon splitting these lengths in half, and then wrapping them in cling film, and storing and labelling them. This sounds far simpler than it is. To split the cores (which are taken in gas pipes!), we have to use a router to cut down the pipe on two sides. This is fine until you jam the router and shear the bit like I did (doh!). Then, our (previously successful) female team had to go and find a helpful bloke to come and fix the router (thanks Jez!), so that we could continue. Virginia came and took some photos of us working, and we also filmed our work for possible use on TV (!!!!!).

Having used the router to split the pipe, we then had to use a Stanley knife to cut the caps at each end, and a cheese wire to slice down the mud/sediment and split the core in two. Each of these lengths is then wrapped in cling film. One is kept for analysis and the other is archived so that there is reference material available at all times.

The work this afternoon took us a few hours, and was surprisingly tiring. After our efforts we came in for a cup of tea. There was an impossible puzzle sitting in the tea room that I decided to try and complete (the type where there is a metal ring attached to rope and a wooden shape and you have to try and get the ring free). Apparently, it has been on the ship since the beginning (almost a year now), and no one has yet managed to complete it. We passed it round the room, each trying our best to complete it, again without success. As the tea room gradually emptied, I became more and more determined to work out this puzzle, until I managed to break it (again, Doh!), not irreparably, but enough that it took me ages and ages to get the puzzle back to its original state! Go me!

The ROV was launched just before our watch this evening, and we spent the four hours waiting for sediment to clear as we traced the canyon walls. It was a shame that there was very little for us to see. Visibility is still not good, but we hope that as the ROV climbs higher we will be able to see more of the geological features and organisms that are to be found in this area of the canyon.

So, here’s hoping for a more successful day tomorrow, where I perhaps don’t break quite so many things, and we have some sunshine (it’s been really miserable today!).

 
Virginia writes:

"This morning I woke up earlier (at about 5 am) to see the ROV images at the 1500 m site in the Nazaré Canyon, near the small Portuguese islands named Berlengas. The southern Canyon wall is very irregular in this area. It resembles a very steep mountain slope, with blocks of rock dispersed along the slope and rock outcrops cut by a geometric picture of fracture sets and faults. On the rocks can be seen low amount of sediments. Some sediment can be found in some protected areas between the rocks.

 

Nazaré Canyon walls near Berlengas Islands, shown on the left. At right lower visibility due the high abundance of suspending particles.

 

Doug explained that the geological processes in the Nazaré Canyon are also not very well understood. The rocks that compose their walls are not yet well studied. Internal tides are very strong in this area where the canyon is narrower. They should be the major process for sediment resuspension and transport. Gravity flows also should have an important roll acting as an intermittent force for the sediments transport.

Tidal currents are actively resuspending and transporting sediment in the water column as reflected by the high amount of suspended particles that frequently make difficult the ROV visibility. Density of macrofauna is low in this area. During the period that I stained in the ROV van we observed some sponges, cnidarians (soft corals) and asteroids.

 

Kostas and Mark are deploying SAPS

SAPS (stand alone pumping system)

CTD

A glass fibber filter used by Kostas containing particulate matter from the water column.

 

Kostas and Mark are deploying SAPS (stand alone pumping system) to collect particles from the water, at 10 m of the bottom and at 1550 m. He is using two SAPS which will be pumping water at these depths simultaneously. The depths were chosen based on a CTD profile that was carried out before the SAPS deployment.

The particles will be collected on glass fibber filters and after recovery they will be kept frozen for the rest of the cruise. In the lab they will be freeze-dried and analysed for organic carbon, nitrogen, lipids, pigments and stable isotopes. I found Raquel, Veerle and Helen in the ship hangar working hard.

Helen, Raquel and Veerle cutting halves of the piston cores sections and preparing them to return to England.

 

I don’t know if Helen like much more of Biology or if Geology. She has been working very hard in both sciences. I think that Helen belongs to his school and students but she also belongs to science and perhaps a new geologist is borning. Nice to have Helen with us.

Cutting cores and megacores, sieving mud, looking for and picking benthic foraminifera are my favourite activities on board. I also like to see the sea bottom through the yeas of ISIS. Yesterday Andy received a push core with a very nice rose anemone. He was not happy by the presence of the anemone on the sediment surface. But when we were trying to remove carefully the anemone we had a surprise. A deep-sea giant protozoan was exhibiting its elegant shape, similar to a Bonsai tree.

 

A very nice giant protozoan (unicelular organism) belonging to genus Pelosina

 


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