Mineralogy of Juventae Chasma: Sulfates in the light‐toned mounds, mafic minerals in the bedrock, and hydrated silica and hydroxylated ferric sulfate on the plateau

Abstract

[1] Juventae Chasma contains four light-toned sulfate-bearing mounds (denoted here as A-D from west to east) inside the trough, mafic outcrops at the base of the mounds and in the wall rock, and light-toned layered deposits of opal and ferric sulfates on the plateau. Hyperspectral visible/near-infrared Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectra were used to identify monohydrated and polyhydrated sulfate (PHS) outcrops of layered material on the bright mounds. Most of the monohydrated sulfate signatures closely resemble those of szomolnokite (FeSO 4 ÁH 2 O), characterized by a water band near 2.08 mm, while some areas exhibit spectral features more similar to those of kieserite (MgSO 4 ÁH 2 O), with a band centered closer to 2.13 mm. The largest PHS outcrops occur on the top of mound B, and their spectral features are most consistent with ferricopiapite, melanterite, and starkeyite, but a specific mineral cannot be uniquely identified at this time. Coordinated analyses of CRISM maps, Mars Orbiter Laser Altimeter elevations, and High Resolution Imaging Science Experiment images suggest that mounds A and B may have formed together and then eroded into separate mounds, while mounds C and D likely formed separately. Mafic minerals (low-Ca pyroxene, high-Ca pyroxene, and olivine) are observed in large $2-10 km wide outcrops in the wall rock and in smaller outcrops $50-500 m across at the floor of the canyon. Most of the wall rock is covered by at least a thin layer of dust and does not exhibit strong features characteristic of these minerals. The plateau region northwest of Juventae Chasma is characterized by an abundance of light-toned layered deposits. One region contains two spectrally unique phases exhibiting a highly stratified, terraced pattern. CRISM spectra of one unit eroded into swirling patterns with arc-like ridges exhibit a narrow 2.23-mm band assigned to hydroxylated ferric sulfate. A thin layer of a fractured material bearing an opaline silica phase is observed at the contact between the older plateau unit and the younger hydroxylated ferric sulfate-bearing light-toned layered deposits. Hydrothermal processes may have produced an acidic environment that fostered formation of the hydrated silica and hydroxylated ferric sulfate units.

Mineralogical characterization of Juventae Chasma, Mars: evidences from MRO-CRISM

“…CRISM image frt00005814 also shows weak absorptions at 2300-2350 nm, and 2500-2550 nm, which are diagnostic feature of carbonates. Therefore, the images adjacent to the image frt00005814 could be also processed in further studies for better identification of carbonates, because till now only mono to poly hydrous sulphates, opaline silica and mafic minerals has been reported (Bishop et al, 2009). The palaeo-environmental conditions of the region have been developed by many scientists.…”

“…CRISM acquires images in high-resolution targeted mode using two detectors: a VNIR detector in the spectral range 360-1050 nm and an IR detector covering 1000-3900 nm (Murchie et al, 2007(Murchie et al, , 2009). Selected CRISM-Full Resolution Targeted (FRT) has been processed using the steps defined by the team over the first Mars year (Murchie et al, 2009).…”

“…Selected CRISM-Full Resolution Targeted (FRT) has been processed using the steps defined by the team over the first Mars year (Murchie et al, 2009). Firstly, the CRSIM data was converted to I/F by subtracting the instrument background, dividing by processed measurements of the internal calibration standard, and dividing by solar irradiance (Bishop et al, 2009). Then, images are processed using a cleaning algorithm to remove noise and large spikes within the data because of instrument effects [Parente, 2008].…”

“…Kieserite is found in the deposit, surrounding the gypsum deposits and is associated with other rough material at lower elevation (Gendrin et al, 2005). Later, the identified mineralogy shows the presence of sulphates on light toned layers, mafic minerals at bedrock and hydrated silica and ferric sulphate on plateau (Bishop et al, 2009(Bishop et al, , 2007aMilliken et al, 2008). Juventae Chasma is 3 km long depression and likely to be formed due to stresses related to Tharsis rise during the late Noacian to early Hesperian period (Lucchitta et al, 1992;Chapman et al, 2003).…”

“…Generally, it is considered as a part of Valles Marineris system, but is separated from the main channel by 500 km. Deposits of Juventae Chasma has been studied by using Mars Global Surveyor (MGS), Mars Orbiter Camera (MOC) and Mars Odyssey Thermal Emission Imaging System (THEMIS) data, Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) (Chapman et al, 2003;Catling et al, 2006;Bishop et al, 2009). The surface of Juventae Chasma has been marked with the presence of mounds and plateau, towards the outflow of Maja Vallis (Chapman et al, 2003;Catling et al, 2006).…”