Holding Patterns

Clearance Update. 19:56. We still haven't received our clearance to dive in the area. However, we have been assured we should be able to dive tomorrow... so keeping our fingers crossed!

We last visited this area in 2003 (http://www.alrlab.pdx.edu/research/fieldnotesguaymas.html) and are very excited about returning to one of our favorite deep-sea vent sites in the world. What makes this vent site so different from most of the other sites is that although the hot fluids form in the same way as they do in other deep-sea vent sites (see http://www.divediscover.whoi.edu/vents/basics.html), Guaymas Basin vents are located in the Gulf of California, where the close proximity to land creates a very thick (>300m) sediment layer. When the hot (~300˚C) hydrothermal fluid percolates through this sediment layer it causes the sediments to 'cook' at very high temperatures. The hydrothermal alteration of the sedimentary organic matter produces a complex mixture of petroleum hydrocarbons, short-chain organic acids and ammonia. Consequently, the hydrothermal fluid is less acidic (pH ~5.9) than most other vents sites (average pH 3.5) and contains lower concentrations of metals like iron, manganese and copper because these metals precipitate within the sediment layer as the pH of the fluid becomes less acidic. The vent deposits here are also rich in calcite and aragonite (calcium carbonate). We are interested in whether these chemical and mineralogical differences will influence the microbial diversity (including thermoacidophiles) that colonize the deposits.


Lauri's Guaymas Impressions:

9 November: The Alvin crew was up at six to prep the sub for diving, although we we're still waiting for permission to dive from the Mexican government. The usual launch time of 8 a.m. came and went, as did 9, 10 and noon. After not getting a go ahead at 1:30 p.m., the dive was officially cancelled. So, now I'm caught up with my photo editing and patiently waiting word from Mexico City. One exciting moment of the day came early for the ship's bosun Patrick when he hooked and landed a 25 pound mahi mahi!