Friday, September 28, 2012

Deep-C Geomorphology/Benthic Studies Cruise - Fall 2012

Ship’s Blog:  Weatherbird II (WB1305)
28 September 2012

Map of Cruise Progress (as of 28 September)

Scene on the Weatherbird’s work deck
as the last of 24 multicore tubes were processed.
The mud soirĂ©es have resumed as we wind down our sampling activities.  Previously today, we completed an extensive photosurvey of Seep-C.  This is a natural hydrocarbon seep situated on a mile-wide mound that rises in a plateau almost 200 m above the surrounding seabed.  We did our most sophisticated work to date with the MILET platform as we were able to complete 1 km long tracks over the mound, then fly the MILET up in the water while the ship came around to a new course, and finally play out cable to bring the vehicle in on track on the top of the mound.  This would not have been possible without the superb bathymetry collected for us by the Okeanus Explorer because we needed to have confidence that we would not hit the bottom turns and that we knew when we would begin to approach the bottom as we brought the vehicle on track.

Samira and Arvind log core photographs
and descriptions while Chris offers advice.
The result was that we have localized the area of active seepage to be on the southern edge of the mound in an area about 100 x 400 m.  This will allow the next leg to drop its sediment and water sampling right into the most active area.  A similar strategy will be possible for Peanut Hill, so this cruise has accomplished an important objective in confirming the location where our positive control sites for hydrocarbon “contamination” can be sampled.

Samantha, Patrick, Chris, and Nikki: happy to only have one more coring site to go.

Samantha does double duty working on both sediment and water samples.
Nikki, Patrick, and Chris.
The multicoring crew then got a chance to get back in action  after several shifts standing by.  They are getting faster at processing the cores, but it still takes almost 10 hours to complete a 3-drop set of multicores.  By the end, everyone is tired, muddy, and a bit giddy looking forward to a shower and a few hours of sleep.  Less than 24 hours to go before we have to head for Panama City and trade out our science party for the next leg.

Post Author:
Dr. Ian MacDonald

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