Arctic Field Projects



Project Title: Collaborative Research: Sonic Logging the NEEM Corehole, Greenland (Award# 1208806)

PI: Pettit, Erin C (ecpettit@alaska.edu)
Phone: (907) 474-5389 
Institute/Department: U of Alaska, Fairbanks, College of Natural Science and Mathematics  
IPY Project?
Funding Agency: US\Federal\NSF\GEO\OPP\ARC\ANS
Program Manager: Dr. William Wiseman (wwiseman@nsf.gov)
Discipline(s): | Cryosphere |

Project Web Site(s):
NSF_Award_Info: http://www.nsf.gov/awardsearch/showAward.do?AwardN...

Science 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.

Logistics Summary:
This effort is a collaboration between PIs Waddington (1208635, UW, LEAD) and Petit (1208806, UAF). After being invited by the NEEM steering committee to participate, the scientists proposed and have been awarded a RAPID grant to obtain sonic velocity profiles from the deep borehole at NEEM. This work requires a RAPID funding effort because there are no plans to keep the NEEM camp open--and the winch required to conduct this work on site--beyond 2012. In May or June of 2012, a field team of three will spend about three weeks at the NEEM field site conducting the measurements. Two researchers will travel from the U.S. via the ANG logistics chain from Scotia to Kangerlussuaq. They will then travel onward. The third researcher will fly commercially from Copenhagen. Logistics details under Waddington 1208635.

For support details, see 1208806.
SeasonField SiteDate InDate Out#People
2012Greenland - Kangerlussuaq0
2012Greenland - NEEM0
 


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