Stable isotope (δD–δ¹⁸O) relationships of ice facies and glaciological structures within the mid-latitude maritime Fox Glacier, New Zealand

• Main Authors: Appleby, JR, Brook, MS, Horton, TW, Fuller, IC, Holt, KA, Quincey, DJ
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2017
• Subjects: Fox Glacier; New Zealand; Annals of Glaciology
• Online Access: https://eprints.whiterose.ac.uk/133879/; https://eprints.whiterose.ac.uk/133879/9/stable_isotope_d18o_relationships_of_ice_facies_and_glaciological_structures_within_the_midlatitude_maritime_fox_glacier_new_zealand.pdf

Relationships between stable isotopes (δD–δ¹⁸O), ice facies and glacier structures have hitherto gone untested in the mid-latitude maritime glaciers of the Southern Hemisphere. Here, we present δD–δ¹⁸O values as part of a broader study of the structural glaciology of Fox Glacier, New Zealand. We analyzed 94 samples of δD–δ¹⁸O from a range of ice facies to investigate whether isotopes have potential for structural glaciological studies of a rapidly deforming glacier. The δD–δ¹⁸O measurements were aided by structural mapping and imagery from terminus time-lapse cameras. The current retreat phase was preceded by an advance of 1 km between 1984 and 2009, with the isotopic sampling and analysis undertaken at the end of that advance (2010/11). Stable isotopes from debris-bearing shear planes near the terminus, interpreted as thrust faults, are isotopically enriched compared with the surrounding ice. When plotted on co-isotopic diagrams (δD–δ¹⁸O), ice sampled from the shear planes appears to show a subtle, but distinctive isotopic signal compared with the surrounding clean ice on the lower glacier. Hence, stable isotopes (δD–δ¹⁸O) have potential within the structural glaciology field, but larger sample numbers than reported here may be required to establish isotopic contrasts between a broad range of ice facies and glacier structures.