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A geo-update from the Kolbeinsey Ridge

25. July, 2014

Skrevet av: Publisert: Friday, July 25th, 2014

It has been a couple of days since the last update on this blog, and that has a very good reason: all of us have been very busy with the collection and analysis of samples from the hydrothermal vent field and volcanic area of the Kolbeinsey Ridge! In between labwork and processing of mapping data, we also enjoyed the first ROV dives (read more about what an ROV is here)– whilst surely setting the record for the fastest offshore popcorn consumption – and have started a 5K rowing competition in the gym, which is currently led by Ole the AUV technician. Early on Thursday morning, we got clear views of Jan Mayen island when passing by so that some of us ran to the deck to take hundreds of pictures in the cold morning air.

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G.O. Sars passing by Jan Mayen island.

Well – not cold enough for socks in sandals, apparently…

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Arctic air is not cold, according to Alden. 

Below is an update from all the geo-groups on board. Stay tuned for an update from the biologists tomorrow!

 

Geochemistry (by Anne and Tamara)

At the Kolbeinsey Ridge the water column/geochemistry group got samples from 5 CTDs (a Conductivity-Temperature-Depth sensor, read more here).  We took these samples to identify the hydrothermal signal in this area, and to get information about the types of volatiles emitted at the seafloor in this area. In addition, we did pore water analyses on a core taken outside the hydrothermal area that is further sampled by the microbiologists.

Although we are running up and down the stairs all day to check on the CTD, the group is not doing well in the rowing competition. Thinking about it, this might be due to the cake, Sørlandschips (favorite meal of the day) and candy in our daily diet but still, we are very enthusiastic about the rowing and are convinced that we will be champions in the end.

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The CTD is coming back up with samples for the geochemists. 

 

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Ingunn and Ingeborg measuring oxygen concentrations in the sediment core. 

 

Petrology (by Filipa and Cedric)

Ship time is precious and often one needs to make long work marathons to use the most of the time available on a specific area. We had one night to dredge the Seven Sisters volcanic system on the Kolbeinsey Ridge – focusing on the sulfide mineralization and hydrothermal alteration of rocks as well as the fresh volcanic rocks. The first two dredges were made over known active hydrothermal vent areas, previously seen by the ROV Aglantha, and the latter dredges were made on fresh lava flows near and far from the active hydrothermal areas.

Dragging a metal framed basket through the bottom of the ocean can be a tricky operation and the first two dredges got stuck to a rock. 6 000 kg tension on the cable was not enough to break the samples and we had to turn the boat around to finally get us free. Feel the dredge, see the dredge, be the dredge.

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The dredge used by the petrologists to get rocks from the seafloor. 

By early morning there were enough rocks on deck to make the scientists happy and eager to work on. The next step is to prepare the rocks for petrographic observations and geochemical analysis once we are back in the lab.

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A happy petrologist with the result from a rock dredge. 

 

Mapping (by Alden)

As a marine scientist working in acoustics my main goal is to see the seafloor, ideally as well or better than we can see land. For the 2014 expedition to the Kolbeinsey seafloor volcanoes, we needed the best map of the seafloor possible in order to identify small but important hot vent features. To do this we used a state of the art autonomous robot (or AUV – read more here) that acoustically maps the seafloor to a resolution of 3x3cm, covering a square kilometer per hour. At Kolbeinsey we mapped several locations, rapidly processing the sonar maps overnight to use the information for cruise operations the next day. After two days of mapping and many discoveries based on the sonar data, the robot Hugin proved itself as a capable mapping vessel and an essential element of our expedition.

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The ROV Aglantha is being deployed to figure out what is there on the seafloor. 


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