CD179: Deep-sea biology of the Portguese canyons


 


Daily diary

Tuesday 9 May 2006


Emily writes:

"The night shift began with the successful landing of the final piston core at Setubal Canyon. As the core arrived on deck at around 0230, Raquel and fellow scientists eagerly crowed around in anticipation – what would be the outcome? The previous core at this spot had appeared to be unsuccessful, gravel had prevented the corer from penetrating more than ~2m into the sea bed. The core catcher was removed and, like before, gravel spilled out. Another short core.

However, the significance of these samples was yet to be revealed……Once all gear was on board and safely secured, we began the long steam to the next site of interest, Nazare Canyon. No more instruments could be deployed for the next ten hours, so Lee ‘helped’ Teresa and I to mend the swivel for SHRIMP.

We arrived at Nazare at 1200 where SHRIMP (in tip-top condition) was deployed. Unfortunately, an hour and a half later communication was lost and the mission was aborted. The SHRIMP was deployed again, but no luck. Testing showed high attenuation at ~8000m in the fibre optic cable, possibly a result of a kink. The cable was streamed in an attempt to remedy this. Again, no luck.

Meanwhile, Raquel was having much more success with her cores. Cross-sections revealed very large smooth rocks at the base of the core, which graded into sand, on top of which laid oxic mud (indicated by its red colouration). The smoothness of the rocks suggests that they originate from rivers, carried to the canyon via currents...."

Unusual sediments came up in the latest cores



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© Challenger Division for Seafloor Processes
April 2006
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