I was recently out on an off shore exploration cruise where I was part of a team hunting for hydrothermal vent plume signatures in the water column. The entire cruise was three months long and involved two exploration cruises with Conductivity, Temperature, Depth (CTD) sensors and a single cruise with a Remotely Operated Vehicle (ROV), each of which spanned a month long.
The average water depth on the leg I was part of was about 2,500 meters (8, 200 ft) while the second phase went a little deeper to depths around 3,000 meters (9,840 ft). What we found then was that all the plume signatures detected were around the 2,000 to 2,500 meters depth. This led to the conclusion (at least in my mind) that hydrothermal vents can only be found to a maximum depth of 2500 meters.
However, a recent publication by colleagues doing similar investigations in the Mid-Cayman Rise reported the worlds deepest hydrothermal vent. Nicknamed Placard, after one of only two human beings to have visited the deepest part of the worlds oceans, Placard is some 800 meters below Ashadze, the previous record holder at 4,200 meters deep. What is more fascinating about Placard is that, because of its geological make up and location, it hosts life forms that were previously only known to exist at only two other vents; Rainbow and Lost City.
These vents create extremely reducing chemical environments that have the potential to host abiotic organic syntheis relevant to studies if prebiotic chemistry and the origins of life.
“Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise.” By C. R. German, A. Bowen, M. L. Coleman, D. L. Honig, J. A. Huber, M. V. Jakuba, J. C. Kinsey, M. D. Kurz, S. Leroy, J. M. McDermott, B. Mercier de Lépinay, K. Nakamura, J. S. Seewald, J. L. Smith, S. P. Sylva, C. L. Van Dover, L. L. Whitcomb, D. R. Yoerger. Proceedings of the National Academy of Sciences, Vol. 107 No. 29, July 20, 2010.