Update Time!!

So it is the day after Thanksgiving, a little over a week left in the expedition. The Thanksgiving feast definitely lived up to expectations, the food on this boat has probably been the highlight of the trip so far. I would put the quality of this food up against just about any restaurant I’ve ever been to, I’m truly impressed with what the cooks can do on a ship. We have done 18 dredges now and still no metal sulfides (except for the tiny piece with pyrite on it) to make the Nautilus folks happy. The lavas have ranged from rhyolite pumice, which we haven’t seen much of since the first few dredges that were very close to the arc volcanic front, to the boninites that we saw early on, and more recently we have seen dacite, some of it very fresh, possibly erupted within the last few years, and even some basaltic andesite. The continuum of lava compositions based on silica composition is basalt (at the low end), andesite (intermediate), and rhyolite (high silica). It is MUCH more complicated than that, but those are the big three that you would learn in a basic geology class. Dacite falls between andesite and rhyolite, so it is a relatively high silica lava, and the stuff that we found was very glassy (cooled quickly) for the most part, almost like obsidian. We may have found some basaltic andesite in the last dredge since we are now dredging the Fonualei spreading center, significantly further from the arc and the influence of water in the mantle, which tends to create higher silica lavas. The only truly unique material was the previously mentioned sulfur.

A cool texture from the underside of a basalt sample. This texture forms on the underside of the roof of the lava flow from the lava dripping when the molten material drains out quickly.

A really cool example of basalt. The right side (black layer) is the glassy top of the lava flow, getting deeper toward the left, where a huge number of green olivine and clinpyroxene crystals have accumulated by settling toward the base of the lava flow.

I know I had said in this post that we hadn't found sulfides, but we finally did find some in a later dredge. They're hard to see in this pic but the darker gray stuff toward the interior is Galena (lead sulfide), and there is a tiny amount of copper and zinc sulfide in some of the samples. It actually looks cooler with a hand lens when you can see all of the individual crystals.

Supposedly in the latest AUV survey, they were able to identify some hydrothermal chimneys, so the next dredge in a few hours may actually find some sulfides or at least some hydrothermally-altered rocks, and perhaps some more deep sea critters. However, as I’ve mentioned it’s very difficult to target a small patch of seafloor with a dredge, so we may yet strike out on sulfides. I’m sure the critters will appreciate it if we miss the hydrothermal vent with the dredge. Apparently an ROV is a much better tool to sample hydrothermal vents, since it can be remotely controlled by someone from the ship and has video capability so they can see exactly what they are sampling. The AUV is really just a small-scale mapping tool that may tell them where the vents are located, but it sounds like it would be ideal to have both and AUV and ROV to really locate and sample the hydrothermal materials. Since Ken is not particularly interested in sulfides, he’s been pretty happy with all of the lavas that we’ve found, and hopefully once he analyzes the lavas back at UH, I will ultimately be able to correlate some of his findings with my own observations on the morphology and structure of the spreading centers. Fernando has also gotten them to sneak in a little mapping here and there on transits to various AUV sites to fill in some of the gaps in the bathymetry maps of the area, so that data will be directly useful for my PhD work. We still have some delays with the AUV, although it seems that most of the instrument/software problems are pretty much resolved by now. The problem is that these types of issues should have been resolved before the AUV was ever taken out to sea. We have lost a few days of valuable ship time with all of the AUV issues, something that no one is happy about. Apparently this particular AUV has not been used on a full science mission before and it seems that the crew in charge of it is not particularly experienced or competent, which has exacerbated the problems. They also refuse to deploy the AUV in even slightly rough seas and they won’t deploy at night, so it forces everyone to work around their schedule. I think it’s safe to say that Nautilus will not be using a Geomar AUV in the future. Nautilus is also the first company to use these methods for hydrothermal exploration, so we are essentially testing a whole new methodology for this type of work, which is also the cause of many of the delays and scheduling issues. The TowCam has had a few issues as well, but the dredging has had no problems at all. I guess it’s not surprising that the most low-tech instrument has the least number of problems. The TowCam has come up with some pretty cool photos though, including hydrothermal cracks and mounds on the seafloor, interesting pillow lava structures, huge beds of mussels surrounding hydrothermal vents, shrimp, crabs, fish, branchy and whip corals, crinoids (animals that look like flowers attached to the seafloor), and even an eel that was hiding from the cam under a rock. I’ll try to post a few of these, but with this brutally slow internet connection it’s going to be very difficult. I still want to post a few pics of Samoa too, but it literally takes 10-20+ minutes to upload one photo and sometimes it has an error during the upload and just doesn’t work. The internet connection has been a constant source of frustration.

A beautiful sunset through the A-frame on the aft (rear) deck of the ship. This is the structure that the winch controlling the dredge is routed through.

AUV deployment in action!

Last night, I spent some time out on the upper deck by the bridge listening to some Bonobo (perfect star-watching music) and enjoying some fresh air. There was a beautiful view of the stars and it was refreshing to feel the wind whipping against me, I think I’m going to do that just about every night for the rest of the cruise. I saw a couple shooting stars and even a few flashes of lightning way off in the distance. But, as with my experience on the Langseth previously, the star-viewing is still not as good as I’ve seen out in the mountains of California. Even though there are only a few lights on the ship, it is enough to spoil what should be a perfect view of the night sky. I’ll try to get in at least one more update before the end of the cruise, but that’s all for now…