Preprints
https://doi.org/10.5194/tc-2022-250
https://doi.org/10.5194/tc-2022-250
 
17 Jan 2023
17 Jan 2023
Status: this preprint is currently under review for the journal TC.

Chemical and visual characterisation of EGRIP glacial ice and cloudy bands within

Nicolas Stoll1,2, Julien Westhoff3, Pascal Bohleber4, Anders Svensson3, Dorthe Dahl-Jensen3,5, Carlo Barbante4,6, and Ilka Weikusat1,7 Nicolas Stoll et al.
  • 1Department of Geosciences, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 2Department of Geosciences, University of Bremen, Bremen, Germany
  • 3Physics of Ice, Climate, and Earth, Niels Bohr Institute, Copenhagen, Denmark
  • 4Department of Environmental Sciences, Informatics and Statistics, Ca’Foscari University of Venice, Venice, Italy
  • 5Centre for Earth Observation Science, University of Manitoba, Winnipeg, Canada
  • 6Institute of Polar Sciences, CNR, Venice, Italy
  • 7Geoscience Department, Eberhard Karls University, Tübingen, Germany

Abstract. Impurities in polar ice play a critical role in ice flow, deformation, and the integrity of the ice core record. Especially cloudy bands, visible layers with high impurity concentrations are prominent features in ice from the last glacial. Their physical and chemical properties are poorly understood, highlighting the need to analyse them in more detail. We bridge the gap between decimetre and micrometre scales by combining the visual stratigraphy line scanner, fabric analyser, microstructure mapping, Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry 2D impurity imaging. We classified almost 1300 cloudy bands from glacial ice from the East Greenland Ice-core Project (EGRIP) ice core into seven different types. We determine the localisation and mineralogy of more than 1000 micro-inclusions at 13 depths. The majority of the found minerals are related to terrestrial dust, such as quartz, feldspar, mica, and hematite. We further found carbonaceous particles, dolomite, and gypsum in high abundance. Rare minerals are e.g., rutile, anatase, epidote, titanite, and grossular. 2D impurity imaging with 20 μm resolution revealed that Na, Mg and Sr are mainly at grain boundaries. Dust-related analytes, such as Al, Fe, and Ti, are also located in the grain interior forming clusters of insoluble impurities. Cloudy bands are thus clearly distinguishable in the chemical data. We present novel vast micron-resolution insights into cloudy bands and describe the differences within and outside these bands. Combining the visual and chemical data results in new insights into the formation of different cloudy band types and could be the starting point for future in-depth studies on impurity signal integrity and internal deformation.

Nicolas Stoll et al.

Status: open (until 14 Mar 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2022-250', Giovanni Baccolo, 24 Jan 2023 reply

Nicolas Stoll et al.

Nicolas Stoll et al.

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Short summary
Impurities in polar ice play a role regarding the climate signal and internal deformation. We bridge different scales using different methods to investigate ice from the last glacial derived from the EGRIP ice core in NE-Greenland. We characterize different types of cloudy bands, frequently occurring milky layers in the ice, and analyses their chemistry with Raman spectroscopy and laser ablation-ICPMS 2D imaging. We derive new insights about impurity localisation and their deposition conditions.