Performance and applications of an automated c-axis ice-fabric analyzer

• Published in: Journal of glaciology Vol. 48; no. 160; pp. 159 - 170
• Main Authors: Hansen, Dirk P., Wilen, Larry A.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 2002; International Glaciological Society
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Instruments and Methods; Snow. Ice. Glaciers; Grain size; Ice; Instruments; Performance; Automatic instrument
• ISSN: 0022-1430; 1727-5652
• DOI: 10.3189/172756502781831566

A completely automated instrument for ice-fabric analysis has been built, tested and applied. The analysis of a thin section is performed in two steps. First, the section is loaded into the machine and is automatically imaged in about 16 min. Then, at a later time and convenient location, the grains in the section are identified from a stored image (either automatically or by the user), and the c-axis orientation of each grain is calculated at a rate of 1200 grains h−1. Comparison of automated results with manual Rigsby stage results shows excellent agreement. Diagnostics indicate that the accuracy of the new technique is 0.5° in the c-axis orientation. Two specific applications are demonstrated: (1) the ability to measure internal grain orientations that may reveal internal stress, and (2) the ability to measure very thin thin sections. The latter, combined with the ability to zoom in on small regions of a section, will be useful for examining the fabric of fine-grained (< 1 mm size grains) ice.