2014-2015 Antarctic

The South Pole Ice Core project is a U.S. effort to drill and recover a new ice core from South Pole, Antarctica. The ice core will be drilled to a depth of 1500 meters, providing an environmental record spanning approximately 40,000 years that will be used to investigate the magnitude and timing of changes in climate and climate forcing through time. Drilling is planned for 2014-2015 (~700 m / through the Holocene) and 2015-2016 (to 1500 m / 40,000 years). The ice core we will obtain will be 9.8 cm in diameter.

Using the Blue Ice Drill, this project will collect large-diameter ice cores to (1) investigate carbon-14 of methane in ice during the last deglaciation and the Early Holocene, (2) investigate the carbon-14 of methane, carbon monoxide and carbon dioxide produced in ice by cosmic rays, and (3) continue to age-map the outcropping ice stratigraphy of Taylor Glacier.

This project will use the USGS high−precision temperature logging tool to verify the condition of the main WAIS Divide borehole prior to the use of any other logging instruments. The temperature data resulting from the test will subsequently be used to refine estimates of the geothermal heat flow at the site, the melting rate at the base of the ice sheet, and to reconstruct past surface temperatures using borehole paleothermometry.

This project will utilize the borehole at WAIS Divide to collect a vertical seismic profile (VSP) of the entire ice column to constrain seismic properties through the ice column and link these observations to the physical properties of the ice core itself. The project will also perform a detailed surface−based active seismic experiment to thoroughly image the bed at WAIS Divide and see how well the two experiments correlate to each other. Since seismic attenuation is most sensitive to temperature, the project will use these two seismic datasets collected to create a model for constraining the temperature profile through the ice column.

This project will profile WAIS Divide boreholes with optical logging instruments that permit the study of dust, crystal structure, and ice fabric. In addition, the project will develop novel light-weight fiber-optic instrumentation that allows complex optical sources, electronics, and detectors to remain at the surface, while fibers transmit signals to and from the borehole during logging.

The Velvet Ice project will conduct repeat borehole logging of the WAIS Divide deep borehole to study three primary questions: (1) How does the evolution of ice microstructure with time and stress in an ice sheet relate to impurity content, temperature history, and strain rate history? (2) How do variations in ice microstructure (and impurity content?) affect large-scale (1m to 1000m) ice flow patterns near ice sheet centers? (3) In what ways is the spatial variability of ice microstructure and its effect on ice flow important for the interpretation of climate history in the WAIS Divide ice core? The answers to these questions require integrating existing ice core and borehole data with a detailed study of ice microstructure using Electron Backscatter Diffraction (EBSD) techniques in combination with careful measurements of borehole deformation through time using Acoustic and Optical Televiewers.

The project will measure the internal properties of the ice at Roosevelt Island via borehole logging. Specific logging measurements include ice temperature, sonic velocity in the ice (a proxy for preferred crystal orientation fabric), and optical properties of the ice in the borehole.