Thursday, April 30, 2015

Mariner vent field

We have been working at the Mariner vent field for the past 48 hours or so. For some of us this is one of our favorite places on the bottom of the ocean. Because this deep-sea vent field is very close to the island arc volcanoes, the hydrothermal vent fluids are greatly influenced by very acidic fluids released by the magma chamber below the seafloor.  These acidic fluids mix with the seawater-derived hydrothermal fluids to create highly acidic hydrothermal fluids that leach metals from the oceanic crust, such copper.  Because these fluids are more acidic (~pH 2.5) than the vent fluids to the North (e.g. ABE and previously Kilo Moana) they contain much higher concentrations of metals like copper, zinc and iron. When these fluids form hydrothermal chimneys, they are quite tall spindly structures, venting high temperatures fluids over 360 degrees C. We also found some fluids that were boiling,which causes phase separation and results in rather unusual fluid chemistry.
Copper and iron rich hydrothermal chimneys at Mariner
The bright white areas at the right, that look a little like white flames are fluids that are being emitted and are boiling.
The microbial biofilm on the "Toilet bowl" rock
The 'Toilet bowl' structure
 From a microbial perspective, Mariner is also very interesting. Samples from here, collected in 2005, resulted in the first truly acid and heat-loving ('thermoacidophile') microbe from deep-sea vents. But also the microbial communities associated with these hydrothermal chimneys are dramatically different from those in the North.  One area that has yielded DNA sequences of heat-loving microbes never before found at deep-sea vents is where a structure we call the 'toilet bowl' is located.  So this vent field has great potential for discovery of new microbes and providing deeper insights into the diversity and extent of life on Earth.
Samples are placed in 'bioboxes' on the Jason.  Note sample still 'smoking'

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