Sedimentation associated with Antarctic Peninsula ice shelves: Implications for palaeoenvironmental reconstructions of glacimarine sediments

Journal of the Geological Society, May 2002 by Evans, J, Pudsey, C J

However, the common characteristic of ice-shelf sedimentation, regardless of regional variations, is the dominance of coarse-grained, proximal glacimarine lithofacies, and the lack of subaqueous outwash/meltwater-deposited sediments.

In Arctic environments such as East Greenland, Canada, SE Alaska and Svalbard marine-terminating ice masses typically form tidewater glaciers with grounded or partially floating margins. Ice proximal glacimarine sediments deposited in these settings are dominated by subaqueous outwash in the form of grounding-line fans and mainly laminated and stratified muds, with massive, frequently bioturbated muds typical of more ice-distal locations (e.g.Elverhoi et al. 1983; Mackiewicz et al. 1984; Powell & Molnia 1989; Boulton 1990; Cowan & Powell 1990; Hein & Syvitski 1992; Cowan et aL 1997, 1999; Smith & Andrews 2000; O Cofaigh et al. 2001). In East Greenland, ice-distal environments are dominated by the deposition of massive diamicton facies by iceberg rafting and scouring (Dowdeswell et al 1994). By contrast, proximal ice-shelf sediment facies of Antarctica are dominated by coarse-grained lithofacies (diamicton, gravel-rich and sand-rich facies), and subaqueous outwash is rare, reflecting the colder polar environment and lack of subglacial meltwater. Thus we can differentiate between polar ice-shelf regimes and more temperate or sub-polar tidewater glacimarine systems on the basis of ice-proximal sediment facies associations, thereby enabling their discrimination within the geological record (cf. Powell & Alley 1997). Furthermore, facies successions document the transition from grounded ice to proximal ice shelf and distal ice shelf and/or open marine conditions, thereby providing us with an analogue for the response of polar ice masses to climate warming. This information can in turn be used to assess the stability of past ice shelves using the geological record and determine their response to past climate change in any future work.

We thank the officers and crew of RRS James Clark Ross and the British Geological Survey team for coring during cruise JR48. We also thank M. Tabecki, B. Porter, L. Martin and D. Goode for technical support. We are grateful to C. O Cofaigh (Bristol Glaciology Centre) for considerable and useful discussions and comments on the manuscript, and to the additional comments by D. Cantrill, D. Hodgson, A. Troedson and E. Wolff (British Antarctic Survey). We thank R. D. Powell and D. Pirrie for constructive formal reviews of the manuscript.

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