PLASTIC DEFORMATION PROPERTIES OF GREENLAND ICE CORE SAMPLES

• Main Authors: ショウジ ヒトシ, ナリタ ヒデキ, ミヤモト アツシ, ワタナベ オキツグ, Hitoshi SHOJI, Hideki NARITA, Atsushi MIYAMOTO, Okitsugu WATANABE, Henrik B. CLAUSEN, Josef KIPFSTUHL
• Format: Report
• Language: English
• Published: ABSTRACT 1997
• Subjects: Greenland; Dye 3; Dye-3; Greenland ice core; GRIP; ice core; Ice Sheet; Polar meteorology and glaciology; Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3994; http://id.nii.ac.jp/1291/00003994/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3994&item_no=1&attribute_id=18&file_no=1

Mechanical property studies have been conducted on deep ice core samples to understand the flow dynamics of large polar ice sheets. Uniaxial compression tests were done both on the Dye 3 and GRIP ice core samples from Greenland. The stress axis is inclined 45 degree from core axis in order to have information on horizontal shear deformation behavior of an ice sheet. The results were analyzed by using an enhancement factor, E. C-axis orientation fabric is a dominant factor for E values and can be estimated from vertical compression strain (N. AZUMA and A. HIGASHI, 1985) if preferred orientation is developed by crystal rotation process without recrystalization. E values from Dye 3 and GRIP samples were plotted with normalized depth (=depth/ice thickness), which is a measure of vertical compression strain. Down to a depth around 60% of ice thickness, the E value stays constant around l, and increases below that depth as expected from the single maximum fabric in deeper places. Below a depth around 70% of ice thickness, E exceeds about 10 and E of GRIP ice samples is higher than that of Dye 3 samples in general. This difference could be attributed to chemical impurity contents and/or ice stratigraphic features such as cloudy bands.