The science team is getting ready to sample cores at the IODP core repository in College Station, Texas. We have been working on finalizing our sampling plans over the past few weeks. Check back here in two weeks, as I will be showing you how we continue our work.
We are having a very smooth transit, very unusual actually: the seas are flat. We are now approaching the coast of Tasmania, but unfortunately it is foggy. Still, it is nice and warm now outside, so I spent some more time on deck today. The ropes are already out: we will arrive in Hobart tomorrow morning, one day early. It was a successful cruise in many aspects: from a personal perspective and from a scientific perspective.
The last couple of days were busy and eventful. Even out here in further from Antarctica, icebergs were approaching the ship and at one point we had to pull out of the hole and get out of the way. Luckily we were able to drop a free-fall funnel, which is a several meters wide fennel that can be assembled to fit around the drill string and drop to the sea floor through more than 3 km of water. When we got back on site we were able to find the funnel and get back into the hole. We were able to w
atch the reentry into the hole on the monitors in the labs: amazing thing to see them trying to put a 3km pipe long into a 30 cm hole, imagine that.
ore cores. And then around 11 AM this morning the last core came on deck. After getting all the more than 3 km of pipe back on board we are leaving Antarctic as we speak. It is time: we have ran out of napkins (toilet paper, neatly folded up is used instead) and we are craving for some fruit and crisp salad!
he debris then gets carried off-shore by icebergs, which melt and release the rock debris so that it can fall to the sea floor. For a decent recent calving event see for example this website from NASA. It shows a series of images documenting the recent calving of the Mertz Glacier Tongue near to where we are drilling. You may have heard about it on the news, it is going on right now.
oast. Here in this core section is a piece of volcanic rock that may have come from the Ross Sea. I was there two years ago with the Antarctic Geological Drilling program (ANDRILL). There are several volcanic islands there that are composed of volcanic rocks like this one. (See the posts on this blog from 15-16 Oct. 2007.) A glacier may have eroded it there and icebergs may have carried it out here.
This is Annick, one of the two down-hole loggers. Here she was getting ready to start her work. The down-hole loggers were very happy the last couple of days, because they finally had a chance to collect some data. Poor drillhole conditions and bad weather did not make it possible to log any previous boreholes. The down-hole logging is very important for our studies. It is the only way to collect an almost continous record of the formations in the subsurface. During drilling there are always core breaks or sections that are not recovered, e.g. because the beds in the subsurface have too many large stones in them, or because the material is too soft or too loose. The down-hole logging provides a means to collect data on these missed sections. The loggers use several sets of tool, or instruments that are lowered into the bore
hole. One of them is the formation microscanner (FMS), which provides an image of the borehole wall. You can even see rock clasts in the borehole wall with this. Another tool is the gamma-ray tool. This tool is able to detect potassium-bearing minerals by exciting the potassium atoms with a radioactive source. In many cases the potassium-bearing phases are clay minerals, so it can be used to pick up fine-grained beds that were missed when coring. Other tools measure the resistivity of beds by sending a current trough the formation. Sands usually have high resistivity, so it is very useful to pick up coarse-grained beds. You can see some of the tools in the box on the photo to the right. These tools are lowered into the borehole on a wire, after the hole has been prepared for logging.
Today was like many days on the cruise. Core was coming up and we were processing it through the lab. In the afternoon we stopped drilling and the hole was prepared for down-hole logging. More on that tomorrow. This may have been the last bit of core that we describe on our shift, so it is a good time to explain what goes on with these cores before we get them on the table. Here you can see Erik and John splitting a core for us. The core is hard, like rock, so they 
use a rock saw to cut it into two equal halves. One half is the Archive half: we get to describe that one and it is kept in pristine condition as much as possible. The other half is the Working half: that half gets sampled, so small pieces are cut out for laboratory analyses. After the split, we describe the features visible on the cut face of the Archive half. Today most of the rocks were laminated and some had nice microfaults (see photo). After core description the cores are photographed using a line-scan imager a
nd fed through a logging track for measurements of color reflectance and magnetic susceptibility. After we have finished the measurements the section halves are wrapped in cling wrap and then fed into a D-tube for storage. Here you can see the D-tubes: those with the red caps are for Archive halves and those with the black caps for the Working halves.
For the past days we have done our best to reach the drillsites 9B and 8A near the coastline (see ice image in previous post). We did drill there for a while with great success befor
e the storm, but after the storm the ice had shifted and we were not able to get back into the area. There are too many icebergs and pieces of multi-year sea ice. We did see some more of the coast of Antarctica and more penguins, Adelie penguins this time, on icebergs. The penguins have big bellies and look very well fed at the end of the summer. They are ready to face winter, which you can tell, is now coming soon.
We had very stormy weather over the past three days. The waves were up to 25 feet (8 m). For some reason the motion of the ship was very irregular and we were rolling around in our beds and not sleeping very much. Today the storm had died down and we tried to get back to our site near the coast, but poor visibility because of snow and the ice conditions made us turn back. The storm has broken some icebergs into numerous small pieces and has shifted some larger ones around. We also received a warning from the Naval Ice Center that a large piece of the Mertz Ice Tongue near our drill site has broken off, presumably due to the storm. You can see the crack in the image. The piece of ice that broke off has now been labeled as iceberg C-28, with a size of 43 by 18 nautical miles (80 x 33 km): try to imagine how big that is!
When I got up this morning there were penguins on the icebergs. I saw four of them on a tiny piece of ice. They were black and white and very small, probably chinstrap penguins. I didn't have my camera with me, but Stephanie saw some as well and took a picture. Here it is. These penguins like to hang out on icebergs during the summer. You can find more information about the chinstrap penguin here.
First of all: Happy Chinese New Year! Our Chinese colleagues here on board are celebrating a year of the Tiger. It is also Valentine's Day, and some others were scrambling to have flowers sent remotely. It is fabulous to experience the cultural diversity here on the ship.
This afternoon we arrived at one of the shelf sites where we are going to drill for more Eocene: a time when it is believed there was no ice on Antarctica. On arrival we found that there is plenty of ice now. To reach the site we had to move around a cluster of icebergs. You could follow our curvy route on the monitors that are hanging around the ship that show the transit track. You can see the coastline of Antarctica as a white line below. I was in the galley eating my breakfast this morning when we went around a curve and the ship was leaning quite steeply. When we finally reached the site this afternoon, there was an iceberg sitting almost on top of it. We are now waiting for ice to move out of the 
way so we can drill. The icebergs were beautiful with nice blue ice. But: let's hope that they will be out of sight tomorrow when I wake up, so we can drill. It is getting colder already, now that autumn is setting in here. When we go outside we have to dress in warm clothes and even then the wind is very cold. We do not have much time left on the shelf before winter is setting in: the Antarctic summer is very short.
We are in transit back tot he Antarctic coast to reach a site closer to the continent. We are navigating bergy waters so our route is curvy to get around these obstacles. We are still processing cores from the previous site, which was triple cored. Triple coring is sometimes done to fill gaps in the record caused by core breaks and cores that were not entirely recovered due to the heave associated with large waves. Filling these gaps allows for complete high-resolution climate records, and that is what we are after.
Core barrels are pulled up from more than 3000 m water depth and are filled with delicious green mud. It is busy in the smear slide corner, because the composition of these fine-grained sediments needs to be determined by microscope: the particles are too small to be seen with the naked eye or a hand lens. Kota Katsuki is the day shift smear slide King. On the night shift Masako Yamane is doing a great job (see photo with Kota and Masako). When a new core is split and is brought to the description table, Kota takes smears of the mud with tooth picks and smears the mud on a glass microscope slide. Under the microscope he can identify the different components and determine how many diatoms are in the sediment. Today we were seeing silty clays and diatom-bearing silty clays in different shades of green. There were were also nice 
laminations of silt.
The drilling started out very well yesterday, but unfortunately about 30 meters into the sea floor the drillstring broke off and it had to be left behind in the hole. It was then just time to move out of the shelf area, because of the approaching big storm. We did get diamictites with quite good recovery before the incident. There were big boulders in them that we drilled through as well. These diamictites likely originate from the erosional and grinding action of glaciers, which released their debris upon melting in the ocean, or by sedimentation from icebergs, which are plenty at this site along coastal Antarctica today. Notice the big pink granite clast: quite amazing to find that in a core!
rilling terminated the beacon was floated from the seafloor to the surface and was pulled in. We received an update on the plans for the next site in the core lab, as usual. Co-chief Carlota (seen on the back) here is explaining what is happening. We are in transit so often these days, that when you get up the first question is: where are we, and wh
at is happening? We actually just arrived on our next site in just over 3000 m of water. The weather here is still not too bad, so we may get some coring done before the storm. In the mean time, so many good data sets have come out of some of our previous sites that we are having a science meeting tomorrow to discuss the implications.
Today, as I got up, we passed the Antarctic Circle in transit to the next drill site. We were all taking pictures and watching the ice. When we arrived at the innermost shelf site we were surrounded by so many icebergs that it was too dangerous to stay. A whale came to check us out, but left quickly.
all my cold weather gear on with all the hats and gloves. Bad weather is coming in this evening: we will be hit by 60 knot winds and snow. It is very likely that drilling operations will have to be shut down, but for the moment we have the drillstring in the sea floor and are moving ahead. I just saw the first core coming up and it had mud with gravel in it. The second one is about to come up soon.
lengthens and when the sea ice starts to break up in the spring, so that nutrients are released into the surface waters. The dark layers in the core are created in the autumn and winter, when the days shorten, the sea freezes over, and eventually the polar night takes over. Besides diatoms, we also found fish bones in the dark layers in the cores, predominantly vertebrae. Each light and dark layer forms a couplet representing one year. Like tree rings, changes in the surface climate conditions affect the thickness and composition of each layer. The Adelie Drift probably contains about 10,000 of these laminae (layers) going back 10,000 years. This is a very valuable record documenting short-term climate change in a very remote place on our planet.
piston coring system now (see drilling equipment class in an earlier post). It works like a giant syringe where watery mud is extracted out of the sea floor. The first couple of cores were very soupy and accompanied by a very powerful smell of rotten eggs (H2S). We also had some issues with exploding cores from all the gases that were released out of the sediment: there is a huge pressure difference between atmospheric pressure here on deck and the weight of 1000 m of water pressing on the sediment there below. Here is a photo of what is left of a core liner after the core exploded. Luckily no one got hurt, because everyone is wearing protective safety gear.
Today was a perfect day. When I got up this morning there was no wind, the sun was out, whales were checking out the ship, and we had a view on the coast of Antarctica. That is a lot! A few hours later the first cores came on deck. You can imagine that the whole science team was in a very good mood. The Adelie Coast is one of the windiest places on Earth. The area is usually very foggy with low visibility. None of that seemed true this morning. We were all relaxing a bit before the first cores came up: enjoying the views with the numerous icebergs.
Most icebergs are grounded on the shelf, but a few smaller ones were on the move. We are actually moving out of the way of one now. This evening a few cores were split, and we got to describe them. I will show you some more of that tomorrow. Our internet is going to be down in a few moments. Enjoy the view on the Adelie Coast below. The white above the horizon is the East Antarctic ice sheet, not a cloud. Talk to you later!
We are in transit to the Adelie coast, where our next drill site is located. Unfortunately, bad weather and poor hole conditions prevented down-hole logging at our previous site: I will explain what that is later. In transit to the Adelie coast we expected to encounter icebergs. This afternoon the ship passed a large tabular iceberg. It was first spotted on the radar. Diego, the ice observer then got onto his post (see photo). These large icebergs may calve and produce small ones that are not visible on the radar. They are called growlers and Diego is very good at spotting them. His job is to advise the Captain and first mate so that the ship does n
ot run into them. Visibility was very good this afternoon, so we were doing more than 10 knots despite the ice.
e of the year that is as dark as it gets. Although it got quite cold (1-2 degrees C) a bunch of us were enjoying this view. You can see the people near the bridge to the left, and the dark bump on the horizon is another iceberg. We could see small bits of ice near the ship as well.
We made it! After 1000 meters of drilling the microfossils indicate we are in the Eocene (more than 34 million years ago). Today the last bit of core was split and in the photo you can see the finger pointing at the piece that came from exactly 1000 meters below the seafloor. From the core we can tell that the sediment, which is very fine-grained clay, had been deposited quite gently particle by particle. It became a rock when cement had precipitated in the pores. Numerous burrows in the claystone tell us that the sea floor was once a lively place. The types of burrows, and the microfossils, tell us it was likely a deep marine environment, and that it was a greenhouse world. How much warmer it was here so close to Antarctica and how it got so cold as it is today is what we need to find out next through analyzing samples. Most of this work will be done when we get home. But the important part is done: get the rocks of the right age.
This is the Paleontology Lab. Three paleontologists are busy looking for microfossils who can give us an age for the cores we are recovering. In Antarctica, the diatoms (microscopic algae) are the most important group for the shallower depths in the core. They evolve fast and there are many different species, so overlapping age ranges produce good time resolution. Unfortunately at greater depth below the sea floor it doesn't work as well. Upon burial below sediment layers several hundreds of meters below the sea floor where the temperature and pressure is greater, the skeletons of these organisms (called frustules) dissolve. The frustules are made of opal, a type of silica, and have characteristic shapes, which are lost through dissolution at burial. Fortunately we have other microfossil groups that we can work with to provide an age and then there is the paleomagician!
The paleomagnetists measure the magnetic properties of the sediments. The sediments acquire the magnetic properties through the workings of the Earth's magnetic field. Through time the Earth's magnetic field has been shifting from pointing into the Earth at the North Pole (normal polarity, like today), to pointing into the Earth at the South Pole (reverse polarity). Minerals in the sediments align themselves with the Earth's magnetic field during deposition and so a polarity record becomes entombed into the sediment layers below the sea floor. The record of the Earth's polarity reversals is known from areas of seafloor spreading, where volcanic rocks can be dated through radiometric dating (using radioactive decay of elements in minerals). This record is known as the geomagnetic polarity time scale. Paleomagnetists can count magnetic reversals in the cores back in time and try to match the cores to the geomagnetic polarity time scale to provide an age.
Todays core logging provided some nice animal burrows that were made more than 10 million years ago. As the creature was crawling through the mud, the burrow backfilled, which produced these nice structures. Drilling is continuing at a fast pace and the drill string extends to hundreds of meters below the sea floor. We are now not seeing many large stones or ice-rafted debris, so we may have traveled back into a warmer period already. These rocks show us that the Antarctic climate was changing in the past: from iceberg environments to an environment with no icebergs and a strongly burrowed sea floor. Pretty interesting huh? Let's see what tomorrow will bring...
A core is coming up every hour now and everyone is busy in their labs. Today we logged green mud with diatoms and gravel. Diatoms are microscopic single-celled algae and the gravel indicates the presence of ice bergs. Sedimentologists make visual observations on the cut face of the core and record these on logging sheets and in the database. We also use a microscope to examine smearslides: smears of mud on glass microscope slides. These smears provide an estimate of how much 
of the sediment is made up of diatoms and other fossil fragments, and how much is made up of minerals, such as quartz and feldspar (see below). The proportions of each component are changing throughout the core and are caused by changes in the paleoenvironment and paleoclimate of Antarctica. Our target at this site is to drill deep into the sea floor and recover rocks from a time when Antarctica was ice-free with forests on its coasts. So far we have seen evidence of ice rafting in the form of pebbles, so we haven't yet traveled far enough in time to reach our goal.
Unfortunately we had to abandon the first hole (Site WLRIS-6A in the map) after only 31 m of drilling. It was all composed of coarse sand and gravel (see photo) with just a little bit of mud. Coarse-grained sediments are very difficult to drill, because they are not coherent. The drillhole becomes unstable and is caving in, which can cause the drill bit to get stuck in the sea floor. To prevent this, we had to abandon the hole and go to a different site to reach our objectives. The sand and gravel was an unexpected discovery and we are still trying to explain how it got there, although we know it came from Antarctica. Because we are exploring a part of the Antarctic margin where no one has ever drilled before, such surprises are expected. Our next site is to the northwest of WLRIS-6A. We are there now, and drilling has just started. When I wake up tomorrow morning there will be more core and there will be more discoveries. Stay tuned, it will get even better.
After some problems with APC coring (see drilling equipment class a few posts ago), we have our first core on deck as of this morning. I woke up with the message "core on the floor" on the PA system at 11 AM. Yesterday two attempts were made to launch the piston corer, but one shoe broke off, and the other bent so severely that the drillers couldn't pull it up through the drill pipe. The only solution was to pull all the pipe out and to try again with a rotary core barrel. It was pretty obvious that there was something very hard out there near the sea floor and this morning we found out what it was: gravel. The first core was cut into sections and is currently sitting in the core lab to equilibrate, so that the physical properties will not change while these are measured on the core. After the physical properties have been measured, the core will be split into two halves, and we, the sedimentologists, get to describe the cut face of one half. The other half will be sampled.
When I woke up this morning I was just in time to witness the deployment of the beacon (see photo) to mark our first drill site. We are at 63° 50.48’S, 138ยบ 49.40’E in 3773 m of water. The beacon is a very important piece of equipment because it plays a role in keeping the ship on site. An automated dynamic positioning system drives a series of thrusters that can move the ship sideways, backward and ahead. The beacon will descend to the sea floor, produce a signal, which is received by the ship. If the ship drifts too far off the site the dyna
mic positioning will respond and thrusters will automatically turn on to move the ship back into position.