JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. B2, 2090, doi:10.1029/2001JB001707, 2003
Physical properties of the P96 ice core from Penny Ice Cap, Baffin Island, Canada, and derived climatic records
Graduate School of Environmental Earth Science, Hokkaido University,
Sapporo, Japan
Institute of Low Temperature Science, Hokkaido University,
Sapporo, Japan
Glaciology Section, Terrain Sciences Division, Geological Survey of Canada,
Ottawa, Ontario, Canada
Abstract
[1] Ice cores from nonpolar environments are being developed as valuable paleoclimatic resources. However, the recognition of a climatic signal and the development of timescales in those ice cores are both difficult due to heavy summer melting. A 177.91-m-long ice core (P96) was drilled in such a high-melt area from Penny Ice Cap, Baffin Island, Canada, in 1996. The core covers the Holocene period and has pre-Holocene ice near the bed. The purpose of this work is to investigate the physical properties of the ice and to show how these properties can be interpreted in terms of climatic signals. Visual-stratigraphic observations and measurements of crystal size and c axis orientation were performed using conventional techniques. Melt features provided a clear picture of Holocene summer climatic changes: a warmer period prior to 2 ka, the Little Ice Age, and the modern warming trend. The crystalline structure displayed normal grain growth down to 50 m and recrystallization below this. In the 0–50 m depth interval, periodical variations in crystal size were observed and are attributed to the difference of time for which the ice was soaked in meltwater every season. These variations made it possible to develop an annual record. The c axis fabric evolution displayed a change in the ice flow pattern from divergent, above 140 m depth, to shear-dominated flow below that. The initial fabric of superimposed ice shows a preferred c axis distribution normal to the surface. The fabric is shown to be important for reconstructing mass balance chronologies from ice cores drilled in areas of superimposed ice formation. These physical properties provide information on climatic change.
Received 10 December 2001; revised 17 June 2002; accepted 9 October 2002; published 12 February 2003.
Keywords: ice core, paleoclimate, crystal size, fabric, superimposed ice, recrystallization.
Index Terms: 1719 History of Geophysics: Hydrology; 1827 Hydrology: Glaciology (1863); 3902 Mineral Physics: Creep and deformation; 9315 Information Related to Geographic Region: Arctic region.
Citation: Physical properties of the P96 ice core from Penny Ice Cap, Baffin Island, Canada, and derived climatic records, J. Geophys. Res., 108(B2), 2090, doi:10.1029/2001JB001707, 2003.