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

• Published in: Annals of Glaciology
• Main Authors: John R. Appleby, Martin S. Brook, Travis W. Horton, Ian C. Fuller, Katherine A. Holt, Duncan J. Quincey
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2017
• Subjects: glacier hydrochemistry; mountain glaciers; structural glaciology; Meteorology. Climatology; QC851-999; New Zealand; Fox Glacier; Annals of Glaciology
• Online Access: https://doi.org/10.1017/aog.2017.11; https://doaj.org/article/260d5c7aaeba4a49afcca48706ba5856

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.