| Titre | Reactive gossans in permafrost as indicators of ancient hydrothermal activity on Mars |
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| Auteur | Lemelin, M; Williamson, M -C ; Léveillé, R J |
| Source | AGU Fall Meeting 2020, scientific program; P006-0002, 2020 p. 1  Accès ouvert |
| Liens | Online - En ligne
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| Image |  |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200784 |
| Éditeur | American Geophysical Union |
| Réunion | American Geophysical Union (AGU) Fall Meeting 2020; décembre 1-17, 2020 |
| Document | site Web |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | html; pdf |
| Province | Nunavut |
| Région | Axel Heiberg Island |
| Sujets | chapeaux ferrugineux; pergélisol; glace fossile; cadre tectonique; antécédents tectoniques; système hydrothermal; volcanisme; orifices volcaniques; télédétection; altération; potassium; jarosite; analyses
spectrométriques; roches hôtes; biogenèse; Astronomie; géologie extraterrestre; minéralogie; géophysique; Nature et environnement; Sciences et technologie |
| Diffusé | 2020 12 01 |
| Résumé | (disponible en anglais seulement)
Over the past decade, spaceborne and in situ remote sensing instruments have identified a wide variety of alteration minerals on the surface of Mars. These
studies have also highlighted the potential occurrence of oxidized iron and sulfur species resulting from the alteration of basaltic material under acid sulfate and oxidizing conditions. The detection of these minerals, such as the potassium and iron
hydrous sulfate jarosite, implies rock-water interactions that could have taken place in ancient hydrothermal systems. Jarosite has been identified at several locations on Mars in CRISM images (e.g., Melas Chasma, Aureum Chaos, Eridania basin),
HiRISE images (e.g., Noctis Labyrinthus, Mawrth Vallis, Nilli Fossae) and rover-based investigation (e.g., Meridiani Planum, Gale crater). It is particularly interesting as it can potentially retain textural, chemical, and isotopic evidence of past
history, including possible biological activity, on Mars.
On Earth, jarosite can form in ore deposits or from alteration near volcanic vents, but only persists in arid environments such as reactive gossans. Reactive gossans in permafrost were
mapped at several locations in the Canadian Arctic. These surficial deposits are particularly abundant in the High Arctic Large Igneous Province exposed on Axel Heiberg Island, in Nunavut. Geomorphic studies of gossans and their host rocks suggest
that some deposits are linked to paleo-hydrothermal systems. Thus, we hypothesize that fluids derived from ancient hydrothermal systems on Mars could have melted the thick permafrost and led to the formation of gossanous soils, explaining some of the
jarosite occurrences reported.
Consequently, we studied the mineralogical composition and spectral signature of reactive gossans in the field and in the laboratory with the objective of building a spectral database of minerals that could be
detected on the surface of Mars. Additionally, comparative studies of genetic links between gossans and buried hydrothermal systems on Earth will be carried out to advance our current knowledge of similar geological deposits on Mars and test their
potential to preserve biogenic signatures. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Les chapeaux de fer sont des sols très altérés, riches en fer, qui recouvrent le socle rocheux. Sur Terre, ces dépôts se forment dans un vaste
éventail de contextes géologiques. Les chapeaux de fer que l'on retrouve dans le pergélisol dans les zones à végétation clairsemée de l'Arctique canadien sont des laboratoires naturels pour l'étude du fer oxydé et des minéraux riches en soufre qui se
forment dans des conditions acides et oxydantes. Dans cette présentation, nous comparons les chapeaux de fer et les systèmes hydrothermaux associés sur Terre avec des dépôts géologiques semblables identifiés sur Mars au moyen de méthodes de
télédétection. |
| GEOSCAN ID | 328169 |
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