The polar sulfur cycle in the Werenskioldbreen, Spitsbergen:Possible implications for understanding the deposition of sulfate minerals in the North Polar Region of Mars

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Szynkiewicz, Anna, Modelska, Magdalena, Buczyński, Sebastian, Borrok, David M., Merrison, Jonathan P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: Svalbard; Werenskioldbreen; glacier; Ice cap; Spitsbergen
• Online Access: https://pure.au.dk/portal/da/publications/the-polar-sulfur-cycle-in-the-werenskioldbreen-spitsbergen(caa5ecad-5e9a-47d6-b920-a4276bc592eb).html; https://doi.org/10.1016/j.gca.2012.12.041; http://www.scopus.com/inward/record.url?scp=84873418839&partnerID=8YFLogxK

In this study we investigated the polar cycling of sulfur (S) associated with the Werenskioldbreen glacier in Spitsbergen (Svalbard). Sulfide-derived S comprised 0.02-0.42wt% of the fine-grained fraction of proglacial sediments. These sediments originated from glacial erosion of Precambrian sulfide-rich quartz and carbonate veins. In summer 2008, the δ 34 S of dissolved SO 4 in glacier melt waters (+9‰ to +17‰) was consistent with SO 4 generation from oxidation of primary sulfide minerals in the bedrock (+9‰ to +16‰). The calculated monthly SO 4 load was ~6881kg/month/km 2 in the main glacier stream. Subsequent evaporation and freezing of glacial waters lead to precipitation, accumulation, and temporary storage of sulfate salt efflorescences in the proglacial zone. These salts are presumably ephemeral, as they dissolve during annual snow/glacial melt events.Hydrated sulfates such as gypsum are also important constituents of the low-elevation areas around the polar ice cap of Planum Boreum on Mars. The origin of this gypsum on Mars might be better understood by using the investigated polar S cycle in Spitsbergen as a foundation. Assuming a trace sulfide content in the basaltic bedrock on Mars, the weathering of sulfides within the fine, porous texture of the ancient aeolian strata (basal unit) underlying Planum Boreum could have created elevated SO 4 fluxes (and gypsum precipitation) during episodic thawing/melting events in the past. Limited water activity and prevailing dry conditions on the surface of Mars are the likely factors that accounted for the larger accumulation and preservation of polar gypsum on the surface and its broad aeolian distribution around Planum Boreum. This suggestion is also supported by an experiment showing that gypsum sand can be transported, under dry conditions, over great distances (~2000km) without a significant loss of mass.