| Titre | Gossan Hill, Victoria Island, Northwest Territories: An analogue for mine waste reactions within permafrost and implication for the subsurface mineralogy of Mars |
| Auteur | Peterson, R C; Williamson, M -C; Rainbird, R H |
| Source | Earth and Planetary Science Letters vol. 400, 2014 p. 88-93, https://doi.org/10.1016/j.epsl.2014.05.010 |
| Année | 2014 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20120292 |
| Éditeur | Elsevier |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.epsl.2014.05.010 |
| Media | papier; numérique; en ligne |
| Formats | pdf |
| Province | Territoires du Nord-Ouest |
| SNRC | 87H/06 |
| Lat/Long OENS | -114.9667 -114.9500 71.3667 71.3500 |
| Sujets | résidus miniers; gestion des déchets; élimination des déchets; pergélisol; congélation du sol; glace fossile; géologie extraterrestre; géologie de l'environnement; géologie des dépôts
meubles/géomorphologie; minéralogie; Cénozoïque; Quaternaire |
| Illustrations | location maps; photographs; photomicrographs; schematic representations |
| |
| Programme | adaptation et impacts sur l'environnement, environnement du nord, Géosciences de l'environnement |
| Résumé | (disponible en anglais seulement)
Gossan Hill is located within the Minto Inlier in central Victoria Island, Northwest Territories (N 9 71.36697° W 114.95155°). A study of the mineralogical
associations and geological setting of this deposit indicates that it is an arrested hydrothermal system frozen in permafrost. From above, the hill stands out because of the topographic relief of 75m and the orange-brown colour of the surficial
material. The surface of the hill is marked by areas of concentric colour zonation up to 3 meters across, with light grey centers surrounded by a yellow-orange ring that is surrounded by an orange-brown colour that covers the rest of the surface of
the hill. Trenches dug into these areas reveal that the central zone contains quartz and pyrite +/- native sulfur in a loose aggregate of sand-sized grains. This central area is surrounded by a zone dominated by gypsum and quartz with some jarosite.
Beyond this, the surrounding surface consists of quartz, hematite, and amorphous iron oxides. The radial arrangement of the mineral assemblage indicates an increase in oxidation of sulfur from the center outward. Analysis of isotopic composition of
the sulfur indicates the source of sulfur could be the underlying strata. The hill is underlain by inter-bedded carbonate and sulfate-evaporite sedimentary rocks of the Kilian formation in the upper part of the Neoproterozoic Shaler Super group. The
sedimentary rocks were intruded by diabase sills of the 720 Ma Franklin igneous event, which crop out 2 km to the south of Gossan Hill. The soft friable nature of the deposit and the topographic relief of the hill indicate a post-glacial
(Pleistocene) age of formation. Permafrost has maintained the disequilibrium mineral assemblage since the cessation of fluid flow. Extraction of the permafrost ice from the central zone yields a liquid with a pH of 2.3. The observed long-term
persistence of pyrite encased within the acidic permafrost indicates that oxidation and dissolution reactions common in mine waste are slowed, if not stopped, in such an environment. The predicted rise of Arctic temperatures will cause the active
layer to move deeper and result in the release of the acidic solutions frozen in the permafrost. Water ice or frozen CO2 just below the Martian surface would also preserve such mineral disequilibrium for very long periods of time. No region exists on
Earth where ice has existed continuously for millions of years, but on Mars, some sub-surface ice may be very old. These frozen mineral-ice mixtures could be a repository of ancient fluids. These reactive mineral assemblages and the fluids associated
with them have the potential to indicate that life existed on Mars in the past. |
| GEOSCAN ID | 291996 |
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