- 1University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom of Great Britain – England, Scotland, Wales (rhr34@cam.ac.uk)
- 2Geo- and Environmental Research Center, University of Tüebingen, Tüebingen, Germany
- 3Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences, Potsdam, Germany
- 4Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
- 5British Antarctic Survey, Cambridge, UK
- 6Department of Earth Science and Engineering, Imperial College London, London, UK
Recent work demonstrates that the Skytrain ice core, retrieved from the Weddell Sea Embayment in West Antarctica, can inform us about the (in-)stability of the Ronne-Filcher Ice Shelf and the West Antarctic Ice Sheet in past warm periods. Here we switch our focus to the Last Glacial period at Skytrain and describe our “Calcium Conundrum”, which may be linked to ice sheet dynamics.
The Skytrain calcium record diverges from those of other Antarctic ice cores across several distinct time intervals. The increased Ca at Skytrain is not accompanied by a corresponding increase in other terrigenous elements such as Al. We hypothesize that the elevated Ca intervals result from additional input of relatively local dust, unique to Skytrain. To test this, we present new geochemical measurements on the soluble phase and fully digested dust particles from a ‘regular Ca’ interval (20–31 ka) and an ‘excess Ca’ interval (42–49 ka).
Trace element data confirm elevated Ca levels during the excess Ca interval, associated also with a significant Ba increase relative to Al. However, terrigenous elements associated with silicate minerals exhibit no significant difference between the two intervals when normalised to Al. Radiogenic Sr and Nd isotopes of the regular Ca interval fall within range of South American source areas, typical for Antarctica during the Last Glacial Period. In contrast, 87Sr/86Sr and eNd values for the excess Ca interval are significantly different from those of the regular Ca interval. Using a collation of Sr and Nd isotope data of potential source regions, complemented by new measurements on rocks from the nearby Ellsworth Mountains, we assess the possibility that the recurring excess Ca signal during the Last Glacial fingerprints a dynamic ice sheet in the Weddell Sea Embayment that intermittently exposed nearby nunataks to physical erosion and dust transport.
Additionally, we report the first (to our knowledge) Ca isotope measurements on ice cores in an effort to further fingerprint the source of the excess Ca.
How to cite: Rhodes, R., Pryer, H., Simpson, R., Hoffmann, H., Grieman, M., Stevenson, E., Bradbury, H., Turchyn, A., Humby, J., Marschalek, J., Archibald, E., Bauska, T., and Wolff, E.: Could the calcium conundrum in Skytrain shed light on West Antarctic Ice Sheet dynamics? , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7037, https://doi.org/10.5194/egusphere-egu25-7037, 2025.
