The sea was angry that day my friends...

like and old man in a deli returning soup.  --Angel

Exploring

So Greg did something pretty cool last night. We were just chilling
out on station after midnight with the goal of deploying the seismic
gear after breakfast. Chilling out on station is not a good use of
ship time, and as we had already dropped a piston core and a
hydrocast, and were in the process of taking not one but two plankton
tows (one for the mixed layer at 25 m depth and one for the
chlorophyll maximum zone at the thermocline, around 200 m. A plankton
tow is exactly what it sounds like. We tow a net at a certain depth
for an hour to catch plankton –it also had the added benefit of making
our friendly Restech Keith smell like krill for the rest of the day).
Greg decided the thing to do would be expand our multibeam seafloor
survey from the grid we'd mapped that morning. The cool thing was that
after deciding this, he walked into the main lab, where we were in the
middle of a heated doubles ping pong match, and said "Hey budding
young scientists, does anyone want to look at our bathymetric data,
identify an area of interest, and design a survey plan?" To which
Jeremy and I replied "yes." (Sam and Kelly, the other half of our ping
pong foursome, were running the plankton tow.)
So we sat down and looked at the day's survey data to see what might
be interesting. Our waypoints and survey plan (and planning
scribblings) are plotted in the top photograph. The basemap is
satellite tomography (yeah, did you know they can measure seafloor
topography via satellite? It still blows my mind) which can resolve
good ocean-scale features, like ridges and trenches and abyssal plains
and the like. The finer stuff can't be resolved from satellite (which
is ok, because again: we're mapping the bottom of the ocean with
satellites), and can only be done with shipboard multibeam sonar.
These data are few and far between in the open ocean. Going back to
our survey map at the top, the line of better resolution data going
from southeast to northwest is a shiptrack from the only other survey
ship to have passed by here. Anyway, Jeremy and I sat down to look at
this, and the results from our survey this morning, which are not
included on the map above (the yellow dots you can see are the
waypoints from that survey). The morning's survey and 3.5MHz seismic
showed interesting seafloor features. Particularly, instead of the
gentle slope suggested by the satellites it has several 20 meter
terraces right along where the contours turn from dark blue to
slightly less dark blue. We couldn't survey during the plankton tow
because the ship can only go 1 knot at that time. That was supposed to
wrap up around 4am, which gave us 3.5 hours of survey time. And we had
to be at a certain location at 7:30 to start the seismic. So we
plotted a triangular course following contour lines of the ridge to
the north where we might hope to find those same terraces. We did this
old school, with a protractor and compass. We figured 10 knots over
three and a half hours gave us 35 nautical miles, so we designed a 29
nautical mile course, on the assumption that we may have to slow down
or quit early if conditions dictated it.
All these tasks completed, we wrote down way points in Lat/Long for
the bridge, and I went to bed, because it was three in the morning and
my shift had ended at midnight.
Jeremy took the waypoints up to the bridge and hand-delivered them,
which apparently is preferred, because there are sometimes
miscommunications over the phone. And they did it. Which is really
cool. We were the ones directing the ship.
Taking directions to the bridge is also extremely surreal, as at night
the bridge is completely black so the two officers driving the boat
can see out into open expanse of the ocean. So when Jeremy got up to
the bridge, he stood around the dark for a moment so his eyes could
adjust, then was greeted by a dark figure (it was one of the mates,
Jeff) standing next to an array of dimly lit computer/navigation
screens. After Jeff took the waypoints and plugged them into the
navigation computer (which literally took 10 seconds), the ship was
good to go and was soon pointed happily northeast towards the first
point Chris and Jeremy had selected.
The survey results, which you can see in the second picture, did
reveal some more of those 20 meter terrace features, but only on the
east-ward facing slopes of the ridges. We're not sure why that is,
although we might hypothesize that it's controlled by basement
topography (basement being the bedrock of this ocean ridge). We could
tell you for sure (probably) if we had time to run a proper seismic
survey over these features, but ship time is limited and we're here to
identify sites for ocean drilling to get sediment records of the last
15 million years of climate variability, not study the geomorphology
of the seafloor. But we explored a small area of the seafloor that was
preciously unexplored, and that was a pretty cool thing to do.

Posted by Chris (writing in the first person, except for right now)
and Jeremy (writing in the 3rd person)

Marine Mammal Observers observing the sunset

And doing a fine job of it, too. You can also see Clint to the right
and Matt the Res Tech down on the bow. You might also notice that the
ocean is no longer the placid lake it was for most of the last week.
The picture doesn't do it justice (does it ever?), but those are ~5'
waves (I think). Not exactly the Southern Ocean, but noticeable after
so many days of calm. They make ping pong more interesting, at least.

We've been shooting a seismic survey all day, and those of us not
actively involved in seismic data acquisition (i.e., everyone but Kim)
have been busy splitting, describing, and sampling cores. It's quiet,
lazy work in an air conditioned lab, away from the sun and heat and
salt spray. In fact, until I went to watch the sunset I hadn't been
outside all day.

posted by Chris

Rhizon Pore Water Sampling

Interstitial water samples are a crucial component of marine
scientific coring expeditions. Although it has long been understood
that pore water affects a range of processes including: fluid flow,
mineral diagenesis, microbial reactions, etc. scientists were unable
to collect high resolution (thinly spaced) water profiles due to
methodological issues. The traditional method of cutting small core
sections and squeezing the water out (just as one would squeeze an
aluminum can for recycling) ruined the sedimentary record and often
forced scientists to choose between the water and the soil.

On this cruise we are utilizing a better method for pore water
recovery - Rhizons. Rhizons consist of a small hydrophilic polymer
tube supported by a wire that is connected to a flexible hose which
passes water to a collection chamber (syringe in this case). Prior to
collect a small hole is drilled in the core liner and the microporous
polymer tube is inserted into the sediment. The syringe is pulled open
and the vacuum slowly pulls water out of the sediment. Generally, this
process takes between 30 minutes and one hour.

The samples are immediately placed inside a refrigerator awaiting
analysis upon our return to the United States.

Posted by Clint Miller

Kasten Coring!

            On Tuesday, September 17 the science party on the R/V Revelle deployed and recovered a somewhat "old school" core, the Kasten Core. The Kasten core sacrifices length for volume; compared to the typical PVC core liners, with a 4 inch diameter and up to ~12 meters in length, the Kasten core liner boasts a 12 by 12 inch surface area but a maximum recovery of just 3 m. As a consequence you obtain more mud per depth interval, allowing a very detailed picture of the recent past. In regions of high sedimentation rates, high-resolution records of the Holocene (past 10,000 years) may be obtained.
            In the early morning hours, the "A-Team" launched the first and only Kasten Core of the cruise off the northern coast of Papua New Guinea (03° 14.538' S, 143° 04.577' E). Though the cast was successful, returning 2.24 m of sediment from 900 m water depth, a number of complications arose. First, when full of mud (and even without mud) Kasten cores, like piston cores, are extremely heavy and must be mechanically turned sideways before bringing them on deck. Further, Kasten cores allow the sediment to shift when the core is turned sideways. Thankfully, the OSU coring staff came prepared with "liquid foam". We performed a bit of shipside chemistry,mixing a two part resin into an empty (knockoff) Pringles can to mix for 50 seconds before dropping the concoction, Pringles can and all, into the top of the core. We expect to find a diagnostic "Pringles layer" within the core as evidence of this event. After a suspenseful 10 minutes the foam appeared to have set and we proceeded to bring the core inboard.

Empty Kasten corer just prior to being launched.

Still, our work was not yet done. We needed to determine how to archive and move ~ 1000 (+/- a bajillion) pounds of mud into the refrigerated van (aka reefer van). The main section of the core is easily archived in the steel liner within the Kasten Core itself, needing only a lid and two plastic end caps screwed in. However, ~1 ft of mud was trapped within the core cutter, a steel piece at the base of the core that is sharpened slightly at its base to cut easily into the sediment. After some awkward lifting and shaking the majority of the cutter mud was removed intact and placed above the foam at the top of the liner, providing a perfect fit (see picture below). Packed safely within its liner we were ready to move it out of the hot sun and into the refrigerated van.



The Kasten Core in its liner.

Yet once again we were faced with moving ~ 1000 pounds of mud and, at the end of a long shift, the prospect was a little disheartening. With the help of our friendly neighborhood Restech, Keith, we managed to wrestle the core onto a cart, and in a moment of much needed comic relief, we maneuvered the core with Keith sitting on its top across the deck to the reefer van (with Keith giggling happily the whole way). At the van, the cool, though the somewhat creepy, musty, and chemical like air pooled out of van and refueled our strength. One last struggle ensued as we strained moving the core up and into van. Mission accomplished!