Jarosite formation in deep Antarctic ice provides a window into acidic, water-limited weathering on Mars

Many interpretations have been proposed to explain the presence of jarosite within Martian surficial sediments, including the possibility that it precipitated within paleo-ice deposits owing to englacial weathering of dust. However, until now a similar geochemical process was not observed on Earth n...

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Bibliographic Details
Published in:Nature Communications
Main Authors: Baccolo, Giovanni, Delmonte, Barbara, Niles, P B, Cibin, Giannantonio, Di Stefano, Elena, Hampai, Dariush, Keller, Lindsay, Maggi, Valter, Marcelli, Augusto, Michalski, Joseph, Snead, Christopher, Frezzotti, Massimo
Other Authors: Baccolo, G, Delmonte, B, Niles, P, Cibin, G, Di Stefano, E, Hampai, D, Keller, L, Maggi, V, Marcelli, A, Michalski, J, Snead, C, Frezzotti, M
Format: Article in Journal/Newspaper
Language:English
Published: Nature Publishing Group 2021
Subjects:
Antarctica
ice core
Planetary sciences
Mars
Jarosite
mineral dust
Antarctic
East Antarctica
Talos Dome
Antarc*
Online Access:http://hdl.handle.net/10281/299969
https://doi.org/10.1038/s41467-020-20705-z
Description
Summary:Many interpretations have been proposed to explain the presence of jarosite within Martian surficial sediments, including the possibility that it precipitated within paleo-ice deposits owing to englacial weathering of dust. However, until now a similar geochemical process was not observed on Earth nor in other planetary settings. We report a multi-analytical indication of jarosite formation within deep ice. Below 1000 m depth, jarosite crystals adhering on residual silica-rich particles have been identified in the Talos Dome ice core (East Antarctica) and interpreted as products of weathering involving aeolian dust and acidic atmospheric aerosols. The progressive increase of ice metamorphism and re-crystallization with depth, favours the relocation and concentration of dust and the formation of acidic brines in isolated environments, allowing chemical reactions and mineral neo-formation to occur. This is the first described englacial diagenetic mechanism occurring in deep Antarctic ice and supports the ice-weathering model for jarosite formation on Mars, highlighting the geologic importance of paleo ice-related processes on this planet. Additional implications concern the preservation of dust-related signals in deep ice cores with respect to paleoclimatic reconstructions and the englacial history of meteorites from Antarctic blue ice fields.

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