Geochemical and mineralogical composition of cryoconites on Eqip Sermia glacier in Central Western Greenland

The geochemical and mineralogical composition of cryoconites was investigated on the Greenland Ice Sheet close to Eqip Sermia glacier in Central-West Greenland. The X-ray diffraction analysis of two samples collected on the glacial surface showed that they mainly contain three silicate minerals (quartz, amphibole and plagioclase) with little variation in modal composition, and rare oxides. Also X-ray fluorescence geochemical exploration showed a similar pattern for the two samples. Trace elements content normalized to the averaged upper continental crust shows values close to 1, except for the depletion in barium and the enrichment in chromium. This average composition resembles the mean of alterated rock in the surrounding area, indicating that dark material deposition was probably dominated by input of local geological outcrops around the glacial. It is not excluded the contribution of other sources driven by factors such as changes in atmospheric transport of dust on the glaciers due to recent climate warming.