I’ve had some questions about what it is we’re trying to achieve here, so I thought I’d say a few words about that. The purpose of our work here is to establish a robust, long-term history of past Antarctic ice sheet variation and climate evolution. Results will provide a context, or a baseline, for understanding current and future climate change. The Antarctic was chosen because the poles are most sensitive to climate change. In other words, global climate changes are typically seen first and most obviously at the poles and later and less obviously at the lower latitudes.
To achieve our objective, we are drilling a 1000 meter deep drillcore into the sedimentary layers that lie in the Ross Sea. The figure above shows the type of drilling rig we’re using. It’s set up on the sea ice about 35 km from McMurdo Station (I’ll be visiting it later this week, and will post pictures then). We anticipate sampling sediments that range in age from 0 to 17 million years. Environmental conditions in the spot where we’re drilling will be reflected in the sediments we recover. As will drill more deeply and back through time, changes in the types of sediments we recover will record things like changes in the amount of sea ice, the proximity of glaciers and, by proxy, climate.
Our team includes the following types of geologists:
Sedimentologists, who describe the core and provide an interpretation of depositional environment;
Petrographers and geochemists, who examine the chemical composition of the sediments and the waters contained in the sediments. These data provide information about the source regions of glaciers and the type of weathering regime; Paleontologists, who examine the fossils contained in the core. Their data will provide information about the age of the sediments and changes in local ecology that often relate to climate change; and
Geophysicists, who study the physical properties of the core.
I am part of the geochemistry team. My role is to extract and analyze the waters that are contained in the sediments. These are waters that are buried along with the sediments. Most often, the water is seawater. However, we know that the glaciers have advanced and retreated several times in this region. As such, we also expect to find glacial meltwaters buried in certain sediment layers. I extract the water, which is held in the pore space of the sediment, by squeezing samples of the sediment in a metal piston using a hydraulic press. The water comes out a small hole in the base of the piston, and it is collected in a syringe. Yes, that’s me in the second picture, squeezing the bejeezus out of a sediment sample. Using the press, I can apply up to 40,000 pounds of pressure. So far I’ve been getting about 30 ml of water out of sediment sample that is 125 cc. I’ll get less and less as we drill more deeply and the sediment becomes more and more compacted.
Do you like the lab coat? I found it in the supply closet and just had to have it. With everything down here white and gray, a little color is a nice thing.
