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Sufates and iron oxides in Ophir Chasma, Mars, based on OMEGA and CRISM observations
- Source :
- Icarus, Icarus, Elsevier, 2011, ⟨10.1016/j.icarus.2011.02.013⟩
- Publication Year :
- 2011
-
Abstract
- We investigate the sulfate and iron oxide deposits in Ophir Chasma, Mars, based on short-wave infrared data from the Compact Reconnaissance Imaging Spectrometer for Mars – CRISM and from the Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activite – OMEGA. Sulfates are detected mainly in two locations. In the valley between Ophir Mensa and the southern wall of Ophir Chasma, kieserite is found both within the slope of Ophir Mensa, and superposed on the basaltic wall of the chasm. Here, kieserite is unconformably overlain by polyhydrated sulfate deposits and iron oxides. Locally, jarosite and unidentified phases with absorptions at 2.21 μm or 2.23 μm are detected, which could be mixtures of jarosite and amorphous silica or other poorly crystalline phases. The second large sulfate-rich outcrop is found on the floor of the central valley. Although the same minerals are found here, polyhydrated sulfates, kieserite, iron oxides, and locally a possibly jarosite-bearing phase, this deposit is very distinct. It is not layered, almost horizontal, and located at a much lower elevation of below −4250 m. Kieserite superposes polyhydrated sulfate-rich deposits, and iron oxides form lags. The facies of sulfate formation remains unclear, and could be different for the two locations. A formation in a lake, playa or under a glacier is consistent with the mineralogy of the central valley and its flat, low-lying topography. This is not conceivable for the kieserite deposits observed south of Ophir Mensa. These deposits are observed over several thousands of meters of elevation, which would require a standing body of water several thousands of meters deep. This would have lead to much more pervasive sulfate deposits than observed. These deposits are therefore more consistent with evaporation of groundwater infiltrating into previously sulfate-free light-toned deposits. The overlying polyhydrated sulfates and other mineral phases are observed in outcrops on ridges along the slopes of the southern chasm wall, which are too exposed to be reached by groundwater. Here, a water supply from the atmosphere by rain, snow, fog or frost is more conceivable.
- Subjects :
- 010504 meteorology & atmospheric sciences
Outcrop
Iron oxide
Geochemistry
Mars
engineering.material
01 natural sciences
chemistry.chemical_compound
Kieserite
0103 physical sciences
Jarosite
Sulfate
010303 astronomy & astrophysics
Spectroscopy
0105 earth and related environmental sciences
Basalt
Astronomy and Astrophysics
Mars Exploration Program
15. Life on land
Mineralogy
CRISM
Surface
chemistry
[SDU]Sciences of the Universe [physics]
13. Climate action
Space and Planetary Science
engineering
Geology
Subjects
Details
- ISSN :
- 00191035 and 10902643
- Database :
- OpenAIRE
- Journal :
- Icarus, Icarus, Elsevier, 2011, ⟨10.1016/j.icarus.2011.02.013⟩
- Accession number :
- edsair.doi.dedup.....d65518e228d45052383270dd4ae27405
- Full Text :
- https://doi.org/10.1016/j.icarus.2011.02.013⟩