Preprints
https://doi.org/10.5194/tc-2021-190
https://doi.org/10.5194/tc-2021-190

  06 Jul 2021

06 Jul 2021

Review status: a revised version of this preprint is currently under review for the journal TC.

Microstructure, Micro-inclusions and Mineralogy along the EGRIP ice core – Part 2: Implications for paleo-mineralogy

Nicolas Stoll1, Maria Hörhold1, Tobias Erhardt1,2, Jan Eichler1, Camilla Jensen2, and Ilka Weikusat1,3 Nicolas Stoll et al.
  • 1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 2Climate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
  • 3Department of Geosciences, Eberhard Karls University, Tübingen, Germany

Abstract. Impurities in polar ice do not only allow the reconstruction of past atmospheric aerosol concentration, but also in- fluence the physical properties of the ice. However, the mineralogy and location of impurities in ice and the involved processes are poorly understood. We use Continuous Flow Analysis to derive the dust particle concentration and optical microscopy and Cryo-Raman spectroscopy to systematically locate and analyse the mineralogy of micro-inclusions in situ inside eleven solid ice samples from the upper 1340 m of the East Greenland Ice Core Project ice core. Micro-inclusions are more variable in min- eralogy than previously observed and are mainly composed of mineral dust (quartz, mica and feldspar) and sulphates (mainly gypsum). Inclusions of the same composition tend to cluster, but clustering frequency and mineralogy changes considerably with depth. A variety of sulphates dominate the upper 900 m while gypsum is the only sulphate in deeper samples, which however contain more mineral dust, nitrates and dolomite. The analysed part of the core can thus be divided into two depth regimes of different mineralogy, and to a lesser degree of spatial distribution, which could originate from different chemical reactions in the ice or large-scale changes of ice cover in NE-Greenland during the Mid-Holocene. The complexity of impurity mineralogy on the metre- and centimetre-scale in polar ice is still underestimated and new methodological approaches are necessary to establish a comprehensive understanding of the role of impurities.

Nicolas Stoll et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-190', Anonymous Referee #1, 22 Jul 2021
    • AC1: 'Reply on RC1', Nicolas Stoll, 27 Sep 2021
  • RC2: 'Comment on tc-2021-190', Anders Svensson, 23 Aug 2021
    • AC2: 'Reply on RC2', Nicolas Stoll, 27 Sep 2021

Nicolas Stoll et al.

Nicolas Stoll et al.

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Short summary
We mapped and analyzed solid inclusion in the upper 1340 m of the EGRIP ice core with Raman spectroscopy and microstructure mapping, based on bulk dust content derived via Continuous Flow Analysis. We observe a large variety in mineralogy, throughout the core and throughout samples. Main minerals are sulphates, especially gypsum, and terrestrial dust minerals, such as quartz, mica and feldspar. A strong shift in mineralogy occurs around 900 m depth indicating a climate-related imprint.