March 8, 2006
Funded by the
National Science Foundation
Office of Polar Programs
Location: Latitude 64° 2' S, Longitude 55° 03' W
Air Temperature: .3°C
Into the labs
We moved onto location this morning around 5:00 am back at proposed Site 4. The drillers have spent the last 3 & 1/2 to 4 hours stringing drill pipe to the ocean floor. We are beginning to drill ahead with the Alien Corer in place so that we can cut a core. The first coring attempt, late morning, was to no avail. Core barrel came up empty. Second attempt was successful and we recovered our first core, 3.3 meters of glacial marine sediment. We've sectioned the core and brought it into the dry lab to equilibrate to room temperature before we can run it through our Multi Sensor Core Logger. Conditions started to deteriorate rapidly around 1:00 pm with heavy fog and significant ice floes, so we pulled up the drill string to wait for safer conditions.
Total drill string out at our Site 4 was in excess of 350 meters. In order for the drilling operations to be safe, Capt. Mike and the mates must be able to hold the NBP over the drill string in essentially a vertical position. Our safety tolerance radius, within which the ship can drift and still maintain our operations, is calculated at roughly 10% of the water depth, or ~35 meters. Therefore, if because of high winds or poor ice conditions, the thruster and screws controlled on the ship's bridge, can't hold the NBP inside tolerance, the drillers must pull pipe to at least just above sea bottom to avoid damaging the drill string.
It's now early evening and we are back to drilling, attempting to get to our main objective at this location, the dipping sub-crop sedimentary section. A core here with age control will give us a key data point that will determine how we approach the selection of the remaining proposed drill sites. While we believe that this unit is Miocene in age, we really won't know for sure until the paleontologists evaluate samples from this unit. Hopefully, we will know something within the hour. This unit has never been sampled and so the scientists are excited about the geology at this location and how it may begin to provide some answers to the objectives of SHALDRIL II.
Time 9:30 pm
We are now through our 3rd core and at a sub-bottom depth of 29 meters. Still in glacial marine sediments, although the unit is much more compacted. Steve Bohaty, our diatom expert, is running a biostratigraphic analysis on the last two samples as I write this. A decision has been made to wash down to a sub-bottom depth of 50 meters before we take another core in order to be confident we are in the older sub-crop section. It will probably take until after midnight to complete.
Drilling is proceeding well. Time for a shift change.