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Collaborative Research: Sonic Logging the NEEM Corehole, Greenland

General

Organisation
Project start
01.01.2012
Project end
31.12.2013
Type of project
ARMAP/NSF
Project theme
Cryosphere
Project topic
Cryosphere

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland, Mid-West
Fieldwork location

Geolocation is 67.0179977417, -50.69400024414

Fieldwork start
01.01.2012
Fieldwork end
31.12.2012

SAR information

Fieldwork / Study

Fieldwork country
Greenland (DK)
Fieldwork region
Greenland Ice Sheet
Fieldwork location

Geolocation is 77.45, -51.06

Fieldwork start
01.01.2012
Fieldwork end
31.12.2012

SAR information

Project details

02.10.2019
Science / project plan

.

Science / project summary
When NEEM project members drilled through the Greenland ice sheet, reaching bedrock in summer 2011, they collected an ice core containing over 150 meters of ice from the last interglacial period (the Eemian, about 150,000 years ago). As researchers prepare to make a detailed study of this core for past climate information, they need to be able to interpreting the layering and deformation of the ice, which becomes especially difficult, due to crystal orientation (called ice fabric) properties, the deeper in the ice sheet the core is taken. While Crystal-orientation—ice fabric—is random near the surface, it tends to become strongly aligned vertically at depth, as the ice sheet deforms. Yet ice fabric can vary greatly over distances of a few meters as a result of strain history, grain size, and impurity content of the snow, all of which correlate with past climate information. This project’s researchers will use sonic instruments to profile the NEEM ice core hole. They will thus collect detailed information on crystal structure of the ice directly adjacent to the NEEM ice core, an effort that will shed light on flow rate and deformation of the core itself. When combined with thin-section analysis of the ice core, information from these sonic measurements will help researchers make a more precise interpretation of the climate history and ice-sheet flow history contained in the NEEM ice core record. This will, in turn, help scientists provide a more accurate climate history as it is revealed in the core. This work will be the first full-waveform measurement in Greenland, and the first to include dated Eemian ice. The specific goals for this proposal include: 1. Collect full-waveform data in the borehole using sonic logging instruments. 2. Analyze these data for P-wave and S-wave speed and attenuation. 3. Derive a fabric profile from wave speeds and compare with existing thin-section data. 4. Initiate collaborations using the fabric to learn about past ice flow and past climate.
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