An Integrated Study of Interior Layered Deposits in Hebes Chasma, Valles Marineris, Mars, Using MGS, MO, and MEX Data (original) (raw)
Related papers
Hebes Chasma, Mars: Slopes and stratigraphy of interior layered deposits
Lunar and …, 2008
Title: Hebes Chasma, Mars: Slopes and Stratigraphy of Interior Layered Deposits. Authors: Hauber, E.; Gwinner, K.; Gendrin, A.; Fueten, F.; Stesky, R.; Pelkey, S.; Reiss, D.; Zegers, TE; MacKinnon, P.; Jaumann, R.; Bibring, J.-P.; Neukum, G. ...
Journal of Geophysical Research, 2009
New results from the Compact Reconnaissance Imaging Spectrometer for Mars and High Resolution Imaging Science Experiment and Context Imager cameras on Mars Reconnaissance Orbiter provide insights into the origin of interior layered deposits in Valles Marineris from analysis of a thick, well-exposed section in western Candor Chasma. Most of the deposit is dominated spectrally by nanophase ferric oxide like that found in the globally distributed eolian dust, with the addition of a prevalent component of monohydrated sulfates. A rippled mantle containing both pyroxene and monohydrated sulfate emanates from discrete layers, which are interpreted as interbedded basaltic sand. Ferric minerals are observed in most of the sulfate-rich layers, and locally a coarse-grained grayer component has been concentrated from the layers by sorting. Polyhydrated sulfates are concentrated in discrete layers high in the section, implying chasma-scale changes in brine chemistry during formation of the layered deposits. Hydrological models were constructed in order to assess whether evaporite deposition from groundwater discharge could have trapped eolian sediments to form the observed deposits. The predicted thickness and extent of the evaporite-trapped sediment is consistent with the distribution of interior layered deposits in Candor Chasma as well as in other chasmata of Valles Marineris. In this scenario, eolian dust and sand were trapped and lithified by evaporites formed by evaporation of groundwater discharge that was highly localized within the chasmata. Sulfates precipitated in the resulting saline conditions, and diagenetic alteration formed crystalline ferric minerals including hematite. This model links the layered deposits in Valles Marineris and those in Meridiani Planum to a common regional process.
Mixtures of clays and sulfates within deposits in western Melas Chasma, Mars
Icarus, 2015
We have utilized several data sets from multiple spacecraft that have been acquired over a continuous observation campaign across the southwestern Melas Chasma region of Mars. The blocky deposit observed on the chasma floor and on portions of the southern wallrock consists of mixtures of light-and medium-toned materials that exhibit displacement structures consistent with transport down the wallrock and onto the chasma floor. CRISM visible and near-infrared reflectance spectra of the light-toned blocks suggest mixtures of nontronite, jarosite, Al-clays, hydrated silica, and/or an acid leached clay. The medium-toned blocks typically lack spectral features or exhibit signatures of polyhydrated sulfates. Bright layered mounds embayed by blocky deposit materials display spectra consistent with Ca-sulfates (gypsum and/or bassanite) that may have resulted from precipitation of less soluble Ca-rich minerals during ponding and evaporation of dilute fluids along the western chasma floor. Highlights Bright layered mounds on the chasma floor contain Ca-sulfates. A blocky deposit has Fe-and Al-clays, hydrated silica, and/or an acid leached clay. Light-toned deposits along the wallrock contain mixtures of sulfates and clays. Layered deposits to the southeast consist of monohydrated and polyhydrated sulfates. The hydrated minerals and fluvial features formed during the Hesperian to Amazonian.
Icarus, 2010
We have used data from the Mars Reconnaissance Orbiter to study 30-80 m thick light-toned layered deposits on the plateaus adjacent to Valles Marineris at five locations: (1) south of Ius Chasma, (2) south of western Melas Chasma, (3) south of western Candor Chasma, (4) west of Juventae Chasma, and (5) west of Ganges Chasma. The beds within these deposits have unique variations in brightness, color, mineralogy, and erosional properties that are not typically observed in light-toned layered deposits within Valles Marineris or many other equatorial areas on Mars. Reflectance spectra indicate these deposits contain opaline silica and Fe-sulfates, consistent with low-temperature, acidic aqueous alteration of basaltic materials. We have found valley or channel systems associated with the layered deposits at all five locations, and the volcanic plains adjacent to Juventae, Ius, and Ganges exhibit inverted channels composed of light-toned beds. Valleys, channels, and light-toned layering along the walls of Juventae and Melas Chasmata are most likely coeval to the aqueous activity that affected the adjacent plateaus and indicate some hydrological activity occurred after formation of the chasmata. Although the source of water and sediment remains uncertain, the strong correlation between fluvial landforms and light-toned layered deposits argues for sustained precipitation, surface runoff, and fluvial deposition occurring during the Hesperian on the plateaus adjacent to Valles Marineris and along portions of chasmata walls.
Geological context of water-altered minerals in Valles Marineris, Mars
Journal of Geophysical Research, 2008
Greater than 15,000 km 2 of the layered deposits within Valles Marineris are associated with water-altered minerals, yet their origin and history of alteration remain a mystery. There are numerous competing hypotheses for the formation of the interior layered deposits including aeolian, lacustrine, and volcanic. Recent orbiter spectroscopic data have indicated that water has played a role in their geological history. Thermal Emission Spectrometer (TES) measurements have revealed significant crystalline hematite-bearing deposits within Valles Marineris, typically related to interior layered deposits. These hematite deposits, found with a wide range of albedo values, are associated with relatively steep bedrock exposures but can also be seen downslope on flat surfaces where they may be a lag deposit. More recently, Observatoire la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) data have shown hydrated sulfates covering more than 13,000 km 2 area of Valles Marineris. Sulfates are found in numerous topographic settings and geological units, but are typically located along the flanks of interior layered deposits and nearby low-lying floor units. Here we study the detailed morphologies of hematite and sulfate-bearing units such as mantled wall units, mass-wasting blocky deposits, massive floor deposits, and tectonically altered floor units. All of these terrains have diverse erosional styles and varied crater populations. In both hematite-and sulfate-bearing units, occasionally found in conjunction with one another, formation processes require contributions from water. The results indicate a wide range of diversity within an individual mineral class, between mineral classes, and also among morphological types. The diversity of geological settings and properties suggest that any single, unified formation mechanism is improbable.
2010
1] CRISM is a hyperspectral imager onboard the Mars Reconnaissance Orbiter (MRO; NASA, 2005) which has been acquiring data since November 2006 and has targeted hydrated minerals previously detected by OMEGA (Mars Express; ESA, 2003). The present study focuses on hydrated minerals detected with CRISM at high spatial resolution in the vicinity of Capri Chasma, a canyon of the Valles Marineris system. CRISM data were processed and coupled with MRO and other spacecraft data, in particular HiRiSE (High Resolution Science Experiment, MRO) images. Detections revealed sulfates in abundance in Capri, especially linked to the interior layered deposits (ILD) that lie in the central part of the chasma. Both monohydrated and polyhydrated sulfates are found at different elevations and are associated with different layers. Monohydrated sulfates are widely detected over the massive light-toned cliffs of the ILD, whereas polyhydrated sulfates seem to form a basal and a top layer associated with lower-albedo deposits in flatter areas. Hydrated silicates (phyllosilicates or opaline silica) have also been detected very locally on two mounds about a few hundred meters in diameter at the bottom of the ILD cliffs. We suggest some formation models of these minerals that are consistent with our observations.
Journal of Geophysical Research, 2011
A basin-like area containing three interior layer deposits (ILDs) on the southern margin of Coprates Chasma was studied. We interpret the area as an ancestral basin and demonstrate that ILD deposition postdates the formation of the current wall rock slopes. The geometry of the ILD and the wall rock spurs form a catchment area between each ILD and the plateau to the south. Erosional remnants of extensive ash or dust layers deposited on the plateau south of Valles Marineris also crop out on the southern plateau of Coprates Chasma. A mass balance calculation suggests that the volume of each ILD is compatible with the volume of the ash or dust that would have been deposited within each catchment area. We propose that the ILDs likely formed by episodically washing such aerially deposited material down from chasma walls. Rifting of the Ius-Melas-Coprates graben opened the enclosed basin and removed any standing water. Faults within the ILDs are compatible with this chasm opening. Sulfates are associated with the ILDs and light-toned material on the basin floor. We suggest that they result from water alteration of preexisting deposits, though the timing of that alteration may predate or postdate the breaching of the basin. Scours within one ILD are similar to terrestrial glacial scours. During a period of high obliquity ice would accumulate in this region; hence we argue the scours are Martian glacial scours. A late deposited layer marks the end of the active local geological history between 100 My and 1 Gy.
Spectral and geological study of the sulfate-rich region of West Candor Chasma, Mars
Icarus, 2008
Sulfates have been discovered by the OMEGA spectrometer in different locations of the planet Mars. They are strongly correlated to light toned layered deposits in the equatorial regions. West Candor Chasma is the canyon with the thickest stack of layers and one with the largest area covered by sulfates. A detailed study coupling mineralogy derived from OMEGA spectral data and geology derived from HRSC imager and other datasets leads to some straightforward issues. The monohydrated sulfate kieserite is found mainly over heavily eroded scarps of light toned material. It likely corresponds to a mineral present in the initial rock formed either during formation and diagenesis of sediments, or during hydrothermal alteration at depth, because it is typically found on outcrops that are eroded and steep. Polyhydrated sulfates, that match any Ca-, Na-, Fe-, or Mg-sulfates with more than one water molecule, are preferentially present on less eroded and darker outcrops than outcrops of kieserite. These variations can be the result of a diversity in the composition and/or of the rehydration of kieserite on surfaces with longer exposure. The latter possibility of rehydration in the current, or recent, atmosphere suggests the low surface temperatures preserve sulfates from desiccation, and, also can rehydrate part of them. Strong signatures of iron oxides are present on sulfate-rich scarps and at the base of layered deposits scarps. They are correlated with TES gray hematite signature and might correspond to iron oxides present in the rock as sand-size grains, or possibly larger concretions, that are eroded and transported down by gravity at the base of the scarp. Pyroxenes are present mainly on sand dunes in the low lying terrains. Pyroxene is strongly depleted or absent in the layered deposits. When mixed with kieserite, local observations favor a spatial mixing with dunes over layered deposits. Sulfates such as those detected in the studied area require the presence of liquid water to form by precipitation, either in an intermittent lacustrine environment or by hydrothermal fluid circulation. Both possibilities require the presence of sulfur-rich groundwater to explain fluid circulation. The elevation of the uppermost sulfate signatures suggests the presence of aquifers up to 2.5 km above datum, only 1 km below the plateau surface.