Global mineral distributions on Mars

Abstract

[ 1 ] Determining the mineralogy of Mars is an essential part of revealing the conditions of the surface and subsurface. A deconvolution method was used to remove atmospheric components and determine surface mineralogy from Thermal Emission Spectrometer data at 1 pixel per degree (ppd). Minerals are grouped into categories on the basis of compositional and spectral similarity, and global concentration maps are produced. All binned pixels are fit well with RMS errors of 0.005 in emissivity. Higher RMS errors are attributed to short wavelength particle size effects on dust-covered surfaces. Significant concentrations (>0.10) of plagioclase, high-Ca pyroxene, sheet silicates/high-Si glass, and hematite are detected and display distributions consistent with previous studies. Elevated concentrations of plagioclase and high-Ca pyroxene are consistent with basaltic surfaces and are located in low-albedo highlands regions north of $ 45° S. Significant concentrations of plagioclase and sheet silicates/high-Si glass and low concentrations of high-Ca pyroxenes are consistent with andesitic surfaces and are concentrated in both southern and northern high-latitude, low-albedo regions. Andesitic surfaces in the southern hemisphere have a lower spectral contrast than northern surfaces. An isolated surface located in Solis Planum is spectrally distinct but compositionally similar to other surfaces interpreted to be andesitic in composition. Concentrations of olivine below the detection limit correctly identify its presence in two of three locations. Potassium feldspar, low-Ca pyroxene, basaltic glass, olivine, sulfate, carbonate, quartz, and amphibole are not detected with confidence at 1 ppd. The results presented here indicate a predominance of volcanic compositions within Martian dust-free surfaces.

Physical abrasion of mafic minerals and basalt grains: Application to martian aeolian deposits

“…The majority of mature terrestrial sands are dominated by quartz, which is abundant in source lithologies on Earth and is physically and chemically stable under a wide range of conditions. On Mars, however, terrestrial standards of sediment maturity are not applicable due to the martian surface having a predominantly mafic composition (e.g., Bandfield, 2002). The presence of mafic minerals indicates sediment immaturity under terrestrial conditions because many mafic minerals are highly susceptible to chemical weathering, are softer than quartz, and contain cleavage planes, making them less durable during physical transport.…”

“…The variety of mafic minerals and volcanic materials were chosen based on remote sensing observations of Mars. The surface of Mars is predominantly basaltic in composition and comprised of minerals rich in magnesium and calcium (e.g., Bandfield, 2002). Therefore, the materials chosen for this study include olivine (forsterite), clinopyroxene (augite), plagioclase (labradorite), volcanic glass and fine--grained basalt from the Columbia River Basalt Group volcanic deposits.…”

Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars

“…Apart from satellite observations of valleys and channels formed by aqueous activity, there are few quantitative measures (e.g., Thermal and Electrical Conductivity probe on Phoenix Lander; Compact Reconnaissance Imaging Spectrometer for Mars; High Energy Neutron Detector on board Mars Odyssey spacecraft) of significant amounts of liquid water at the surface of Mars today (3)(4)(5). Secondary minerals such as carbonates and sulfates record physicalchemical settings of the environment in which they are formed and geochemical relations between the atmosphere and the Martian surface (6). Unlike terrestrial carbonate sediments, the Martian surface lacks large amounts of carbonates despite a CO 2 -rich (95% vol∕vol) atmosphere, though, there is evidence of Mg-Fe rich carbonates (16-34 wt %) in the Columbia Hills and <5% CaCO 3 in Martian dust and soils (3,(7)(8)(9).…”

Developing luminescence dating for extraterrestrial applications: Characterization of martian simulants and minerals

“…Most martian meteorites do not match well with the spectral characteristics of the martian surface and therefore may not be representative of martian soils (Bandfield, 2002). However, they are the only martian materials currently available and are therefore worthy of study.…”

“…Spectra from these instruments distinguish two different types of regolith on Mars, namely Type I (basaltic mineralogy) and Type II (andesitic mineralogy). Both types of regolith, according to the TES results, are composed of plagioclase feldspars, pyroxenes (primarily augite and diopside), and hematite, and the Type II material contains an abundance of obsidian or volcanic glass (Bandfield et al, 2000;Bandfield, 2002). Based upon these results, two mineral mixtures have been created in the OSL dating laboratory at OSU to be used as martian regolith simulants .…”