2016-2017 USAP Field Season
EXPROBE-WAIS: Exposed rock beneath the West Antarctic Ice Sheet, a test for interglacial ice sheet collapse
Dr. John Stone
University of Washington
Supporting Stations: McMurdo Station
Researchers with this project seek to determine whether the West Antarctic Ice Sheet (WAIS) has collapsed in the past, exposing bedrock that is currently covered by the ice sheet. The project will involve drilling through the ice sheet to recover cores from underlying bedrock. These cores will be analyzed for isotopes produced by cosmic radiation, thus testing whether bedrock surfaces beneath the ice sheet have ever been exposed during warm climatic periods in the past. Multiple cosmogenic isotopes will be measured on recovered cores to constrain the timing of last exposure, duration of past exposure periods, and whether surfaces have been exposed one time or many. Stable isotope measurements on ice from above the bedrock surfaces will provide additional constraints on the timing of last exposure. Results will indicate whether warm interglacial periods such as Marine Isotope Stages 5e, 11, or 31 produced significant WAIS deglaciation. By pointing to the paleoclimatic conditions associated with past thinning of the ice sheet, these results will help to identify future climatic factors and thresholds likely to endanger the WAIS.
Field Season Overview
Three scientists and three drillers from T-150-M (Albert) will be supported by a traverse crew of four and one mountaineer at a field camp close to Pirrit Hills, in the Weddell Sea catchment of the West Antarctic Ice Sheet (WAIS). The site is 530 km beyond WAIS Divide camp. The traverse crew will travel from McMurdo Station to WAIS Divide in early November to prepare equipment. Drillers and scientists will deploy to McMurdo in early November to receive cargo and organize onwards shipment of drilling and camp supplies and equipment to WAIS Divide. This group will move to WAIS Divide in late November as the traverse finalizes preparations and departs. Cargo and passengers will be transported from McMurdo to WAIS Divide by LC-130. The traverse will take approximately one week to travel from WAIS Divide to the Pirrit Hills region. During this time scientists will deploy to Pirrit Hills by Twin Otter in order to establish a light camp and prepare for the arrival of the traverse. The full project team will converge at the drill site in early December. Drilling operations are expected to take three to four weeks, concluding in late December. This includes drill set-up, drilling and casing the pilot hole, access and core drilling, and breaking down the drill at each of the two drill sites. This allows two to three days to move the drill and set up at the second site, approximately 500 m away from the first location. After drilling is complete, the traverse will reload and will depart for WAIS Divide during the week ending 7 January. The drillers will return to WAIS Divide by Basler at this time, along with rock and ice cores. A mountaineer will move to Pirrit Hills with the outbound aircraft to join the science team for their final geological fieldwork. After returning to WAIS Divide, drillers will return to McMurdo by LC-130. The traverse will arrive back at WAIS Divide around 7 January. Cargo will return to McMurdo by LC-130 during the following week. In McMurdo drillers will re-pack the drill for northbound vessel shipment, completing this during the week ending 21 January. After completion of drilling, scientists will stay on at Pirrit Hills for approximately one week to complete geological fieldwork from a light camp. Three Twin Otter flights or two Basler missions will be needed during the week ending 14 January to pull out the camp and return the scientists and mountaineer to WAIS Divide. These participants will then move back to McMurdo by LC-130 during the week ending 21 January. In McMurdo scientists will organize and consign northbound cargo and return field equipment before departing around the end of January.
Deploying Team Members