Thursday, June 3, 2010

Getting ready for sampling and documentary

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.

In the mean time you can watch a documentary of our expedition here on YouTube in two 10-minute parts: Part One and Part Two

Sunday, March 7, 2010

Transit to Hobart

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.
So what will happen now? In a couple of months time we will get together again at the IODP core repository in College Station, Texas to sample the cores for laboratory analyses. This will mark the second phase of the project and it will be exciting as well, but in a different way.
So that is it for now: I hope you enjoyed the ride!

Tuesday, March 2, 2010

Dropping a free-fall funnel, logging and leaving

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 watch 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.

Logging was successful and after that we got a couple more 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!

Friday, February 26, 2010

Off in deep water with ice-rafted debris

We are approaching the end of the drilling operations. We need to leave here four days from now to make it to Hobart on time. We are drilling in the distal end of a fan now in nearly 4000 m water depth and find laminated silts and clays and occasional rock clasts. These rock clasts are most likely ice-rafted debris, rock eroded by glaciers, that then calved and produced icebergs. The 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.

However, not all icebergs in this area originate at the Wilkes Land coast. 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.

Wednesday, February 24, 2010

Happy down-hole loggers

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 borehole. 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.

Monday, February 22, 2010

Last bit of core through the lab?

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 and 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.

Saturday, February 20, 2010

LIVE from Antarctica

video
We are drilling in deep water again, off-shore Antarctica. We were unable to reach our coastal site, but we are getting great core from where we are right now. We are now drilling back into the Late Miocene and I hope we are going to reach the Middle Miocene climatic optimum. This is a time when the Earth was slightly warmer than today and it may give us a window into understanding what is up for the future. Let's hope we can get that far.. We are currently at a depth of more than 400 mbsf and we are still drilling.

Friday, February 19, 2010

Another crossing of the Antarctic Circle

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 before 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.

The break in drilling gave us a chance to catch up with report writing, and in the chemistry lab almost all samples are processed now. For you science nerds (like me) out there see this video made by chemist Tina about how high precision balances work on a ship:
If you are interested in what else goes on in the chemistry lab, watch this video, made by Dan Brinkhuis, the shipboard videographer:

Wednesday, February 17, 2010

Storm breaks off large piece of an ice tongue in our research area

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!

Tomorrow we are trying to get back to our drill site 9B between the icebergs again. Let's hope we can make it!

Sunday, February 14, 2010

Penguins!

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.

Saturday, February 13, 2010

Icebergs at night

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.

It was a difficult night with decisions. We were getting great core and were advancing down through the formation to our drilling target, but two icebergs came closer and closer. The ship had its bow turned towards them and the bow lights were shining on them in the darkness. After waiting and hoping that the icebergs would make a turn away from the ship, we had to trip out of the drillhole and the ship had to be moved to get out of their way. Another problem is that a large storm with up to 65 knot winds will arrive here tomorrow, so we temporarily need to move away to the shelf edge to wait out the weather. We will have to return to this coastal site later. It is simply to dangerous to stay here in a storm amidst the icebergs.

Another challenge is that now that we get closer to March the hours of darkness are lengthening. On 21 March the day and the night will be of equal length (12 hours) around this area, near the Antarctic Circle, whereas there were 24 hours of daylight here in late December. In late June there will be 24 hours of darkness.

Friday, February 12, 2010

Between the icebergs

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.

Thursday, February 11, 2010

Triple core and back to Antarctica

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.

The weather hasn't been great lately with lots of rain and snow giving poor visibility. Nevertheless we did see some humpback whales, who were checking out the ship. They were so close that you could see the texture of the wet skin. The weather is reasonable now and I just got outside to watch us passing a huge tabular iceberg. My colleague Kota got sprayed by a wave, because we are still in rough waters. More later once we arrive at our next site, near Antarctica.

Tuesday, February 9, 2010

What's on the table today?

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.

Coring is going well, but we are pulling out of the hole to get some double cores to fill gaps. A weather window is opening up near the Antarctic coast over the weekend and we are going to move there tomorrow evening. This is our last chance to get close to Antarctica before autumn storms and developing ice prevent us from going there. We will most likely return to our present site later to finish coring further back in time. The frequent transits and pull-ups due to weather is taking a bit of a toll on the science team. This is also a difficult period in the cruise: it is still long before we return and it has been long enough that people miss their family and friends. We are also getting a bit tired. The nice core that we are getting, the new friends we are making here on board, and the science, however, is making all good!

Sunday, February 7, 2010

Good old diamictite and another transit

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!
After the drilling 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 what 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.

Saturday, February 6, 2010

Across the Antarctic Circle

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.

We moved to a site further out on the shelf so that we would have the opportunity to move away to the North out of the icy waters if visibility would deteriorate. From here we can still see the pack ice (sea ice) in the distance. It has gotten colder during the day. This evening it was the first time I put 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.

Thursday, February 4, 2010

Seasonal algal blooms recorded in an Antarctic sediment core

For the past two days we have been working on collecting a very unique set of cores. We are currently coring into the Adelie Drift, in a small basin on the Antarctic shelf with a water depth of about 1000 m. The basin is filled with organic sediments composed of more than 90 % diatoms, other microscopic algae and zooplankton. That type of sediment is called diatom ooze. In the photo, you can see a part of a core that we processed today. Each light-colored layer represents the cysts left by a spring bloom of microscopic algae, predominantly diatoms. These diatoms bloom when daylight 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.

The coring of these sediments is a bit different from the drilling we were doing at the previous site. We are using an APC 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.

We were treated with another beautiful day today as well. It is almost unreal: we are in Antarctica and it is supposed to be very cold and windy, but it was just around freezing and in the sun it felt quite pleasant. We did feel the catabatic wind come down from the ice-sheet when the sun was setting, but it wasn't too bad at all. The catabatic wind, is a typical wind of the polar regions, and it develops when air cools over the surface of an ice sheet, becomes dense, and flows out to the coast. The sun is setting at around 11 PM. It does not get completely dark because the sun is only a few degrees below the horizon and the sunset becomes a sunrise within 2 hours. In the photo below the surface above the iceberg is the top of the ice sheet. It is odd to see the sun set above an ice sheet, but it is a magnificent experience!

Wednesday, February 3, 2010

Whales, the sun, core, and a view on the Adelie Coast, Antarctica

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!

Tuesday, February 2, 2010

In transit to the Adelie coast

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 not run into them. Visibility was very good this afternoon, so we were doing more than 10 knots despite the ice.

Later John, the first mate came out and measured the dimensions of the iceberg with a sextant (see photo left). It turned out to be about 3000 feet (1000 m) long: you wouldn't say that, huh? Later that night when I came off shift I had the opportunity to watch the sunset. In the photo, the sun has already set, but it is just below the horizon. In a way it is a sunset and sunrise in one: during this time 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.

I am already excited about tomorrow, when we will arrive on the Adelie coast, only 18 miles from the Antarctic continent. There will be a lot of ice, but hopefully not too much, so we can get some more cores, this time spanning the past ca. 10,000 years.

Monday, February 1, 2010

In the Eocene at 1000 meters below sea floor

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.

But it is not time to go home yet! Instead over the next few days we will move closer to Antarctica. The ice conditions have improved and one of the shelf drill sites on the Wilkes Land coast is free of ice. Now the drillers are pulling up all the drillpipe. We are in more than 4000 m of water, so that is 4000+1000=5000 m (15,000 ft) of pipe that is currently hanging below the ship, imagine that! The pipe is only several inches across, so it behaves like a string of cooked spaghetti. We are currently having high seas with waves up to 20ft (6m), so it is a real challenge for the drillers to pull it in.

I am really excited to wake up tomorrow and perhaps to see the icebergs and the sea ice. We may have to move slowly though because of the bad weather. After this one that we are currently in, a second storm is predicted to hit us. We have had snow today as well, and due to the strong wind and high seas it wasn't pleasant outside. Let's hope it will improve soon.

Friday, January 29, 2010

The bugs and the paleomagician

We are still on site and drilling. A few icebergs have been sited on the horizon and the Captain and the ice observer are watching their movements. This is important, because we are stuck 800 m into the sea floor with a drill pipe and it takes some time to pull all that pipe and to be able to move out of the way. These icebergs are big: they can be several hundreds of meters to miles long and the ship is dwarfed by such a size. In the mean time we are busy with our science.
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.

One interesting aspect of our current location is that we are almost right on top of the magnetic South Pole. It means that if compass needles were freely suspended they would point straight up. The magnetic North and South Pole do not coincide with the geographic North and South Pole. In fact the magnetic poles are always on the move. The magnetic South Pole is now located off-shore Wilkes Land in our area, but about a century ago it was further inland in Antarctica. Douglas Mawson, an Australian Antarctic explorer tried to find it back then, but he barely survived the trip. He almost died of vitamin A poisoning because his sled fell down a crevasse and he and his pals only had the sled dogs to eat, with their livers rich in vitamin A. His two pals (Ninnis and Mertz) died. His journal is a great read, but I am glad our tip is so much more convenient!

Monday, January 25, 2010

Green mud with burrows and no ice rafted debris

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...
Also: the video of our second week on the ship can now be viewed here.

Saturday, January 23, 2010

Olive green mud

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.




Photomicrograph of a smearslide with abundant diatom fragments.

Friday, January 22, 2010

On to the next site

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.

Wednesday, January 20, 2010

Core on the floor!

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.
The core comes out of the core barrel in a 9 m long plastic tube (see photo taken on "the catwalk"). There the length of the core is measured and it is cut into 1.5 m long sections by the curator and his team. In the photo, you can see co-chief scientist Carlota Escutia (in front) and the core techs placing the second core in the holders. This happened just now. The core feels quite cold when it comes up. This is the main reason that it is necessary to hold the core in a rack in the core lab for a while so that it can get to room temperature first. Temperature effects physical properties, such as density. You may know that most materials expand when they heat up, and this reduces their density.

P.S. For all you teachers and professors out there: feel free to use anything from this blog for your classes. This is for you and your students, so that you can take part in the experience! Feel free to ask questions via the comments as well. I will try to answer them as well as I can or get an expert from the rest of the science team to do it if I can't. Additional resources can be found on joidesresolution.org.

Tuesday, January 19, 2010

On site!

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 dynamic positioning will respond and thrusters will automatically turn on to move the ship back into position.

During the deployment of the beacon the drillers were already busy putting together the bottom-hole-assembly (BHA-see the blog a few days ago). A lot of weight was added to the BHA to keep the drill string straight in the deep water that we are in. We are going to start with advanced (hydraulic) piston coring (APC) to refusal and will then continue with the extended core barrel (XCB) in the more compacted sediments at depth beneath the sea floor. The drillers are currently tripping pipe, which can take a while in deep water. They first have to give out 3773 m of pipe to reach the sea floor!

Below are some movies illustrating the drilling preparation activities. If all is well we will have some core tomorrow! It will mean we cannot post to our blogs so much, but I will try to post as much as I can.