Sulfates and iron oxides in Ophir Chasma, Mars, based on OMEGA and CRISM observations

摘要: Abstract We investigate the sulfate and iron oxide deposits in Ophir Chasma, Mars, based on short-wave infrared data from Compact Reconnaissance Imaging Spectrometer for Mars – CRISM Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activite OMEGA. Sulfates are detected mainly two locations. In valley between Mensa southern wall of kieserite is found both within slope Mensa, superposed basaltic chasm. Here, unconformably overlain by polyhydrated oxides. Locally, jarosite unidentified phases with absorptions at 2.21 μm or 2.23 μm detected, which could be mixtures amorphous silica other poorly crystalline phases. The second large sulfate-rich outcrop floor central valley. Although same minerals here, sulfates, kieserite, oxides, locally a possibly jarosite-bearing phase, this deposit very distinct. It not layered, almost horizontal, located much lower elevation below −4250 m. Kieserite superposes deposits, oxides form lags. facies formation remains unclear, different A lake, playa under glacier consistent mineralogy its flat, low-lying topography. This conceivable observed south Mensa. These over several thousands meters elevation, would require standing body water deep. have lead to more pervasive than observed. therefore evaporation groundwater infiltrating into previously sulfate-free light-toned deposits. overlying sulfates mineral outcrops ridges along slopes chasm wall, too exposed reached groundwater. supply atmosphere rain, snow, fog frost conceivable.