Captain Nemo had it easy. When robotic submarines are sent 6000 metres to the bottom of an ocean-ridge rift in March, they will face furiously hot temperatures, pressure that gives oil the consistency of treacle, and rugged cliffs that plunge into the abyss. The pay-off, for an international collaboration of researchers called InterRidge, should be an insight into an unexplored world.
The Cayman trough is a 100-kilometre-long rift in the seabed between Jamaica and the Cayman Islands where the ocean floor is slowly pulling apart and new lava seeps up to fill the gap - a so-called ocean ridge. Such ridges are home to hydrothermal vents, and while vents at 3800 metres below the surface have been explored before, InterRidge plans to visit some of the world's deepest, which lie around 6000 metres down. At this depth, water doesn't boil until it reaches 500 °C.
High temperatures, extreme pressures and the relative isolation of the Cayman trough make it likely that new species of chemosynthetic bacteria and other bizarre organisms will be discovered. Missions to other hydrothermal vents have identified 2-metre-long tube worms, giant clams and "bacterial snow" apparently raining down around the chimneys. Expect dramatic images of weird life forms to start being beamed back by the end of March. Before then, InterRidge vessels will be the first to visit the vent communities of the Southern Ocean, diving to the East Scotia ridge off South Georgia.
The Cayman trough might be more like 25 leagues under the sea than 20,000, but that won't make it any easier. It is an extremely slow-spreading ocean ridge, and the terrain is expected to be more rugged than at previously explored ridges. This means vast boulders and sheer cliffs that will make navigation for submarines like AutoSub6000 difficult. Landing on top of the furnace-like heat of an undersea chimney could also wreak havoc with their circuitry. As Bramley Murton of InterRidge told New Scientist: "Anything we get back will be a bonus."
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"It is an extremely slow-spreading ocean ridge"
Does this mean that these Cayman vents would last longer than the other hydrothermal vents previously discovered?
If so, the isolation and, maybe, the higher boiling point of the water at that depth, combined with this extra time for whatever is there to evolve may well mean that InterRidge will find some seriously weird stuff down there. Can't wait to see it.
PS Season Greetings to all
(except these bloody commercial spammers such as the one above)
In answer to your question - no. The East Pacific Rise is a much faster spreading ridge than the Mid-Atlantic one, but has been in existence for much longer. The Cayman ridge is more like a back-arc spreading centre and hasn't been there very long at all (geologically speaking)
The Mid-Cayman Rise (MCR) has been an active seafloor spreading centre for the past 50 million years or so. It is not a back-arc spreading centre (there is no forearc subduction zone associated with it etc).
The original poster in this thread is correct to speculate that individual vent fields on this ultraslow-spreading ridge may be longer lived than other ridges. While the East Pacific Rise (EPR) is indeed a longer-lived *ridge* than, say, the Mid-Atlantic Ridge (MAR), individual vent fields on the EPR only last for a few decades or so, compared with centuries to possibly millennia (based on sulphide geochronology) for vent fields on the slower-spreading MAR. Slower ridge spreading may result in a lower frequency of tectonic and volcanic events that disrupt the plumbing of individual vent fields. And the MCR is even slower-spreading than the MAR.
The greater depth than most previously studied vent sites, the geographic isolation and the likely higher temperature of vent fluids at greater depth, which may influence vent fluid chemistry, all make this a very hot prospect for some exciting discoveries.
The article doesn't say much. I was at least hoping to read a little about the submarines themselves and the technology needed to explore such an extreme environment.
Yes. It's worthwhile Googling for the manned bathyscaphe Trieste, which went nearly twice as deep to the bottom of the 11km Mariana Trench way back in 1960 and also the hybrid ROV Nereus which went down there in May of this year. Pressure at the bottom is over 1000 atmospheres ... a bit claustrophobic for my liking.
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