Evidence for extensive, olivine-rich bedrock on Mars

Hamilton, Victoria E.; Christensen, P. R.

doi:10.1130/g21258.1

Cited by 197 publications

(233 citation statements)

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“…Some of the rock units in this region are cut by fractures associated with the Isidis impact basin, which is dated to the late Noachian. Because the olivine-bearing units were emplaced before or concurrently with the event that formed the Isidis basin 17,19 , the lack of any aqueous alteration associated with the olivine lithologies, and the lack of alteration of Hesperian lavas, definitively document Noachian phyllosilicate formation.…”

Section: Lettersmentioning

confidence: 99%

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Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument

Mustard

Murchie

Pelkey

et al. 2008

Nature

657

517

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Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument 1,2 , preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity 3 ) were specific to surface environments during the earliest era of Mars's history 4 . Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) 5 of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.High-spatial-resolution, precision-pointing and nested observations of CRISM 5 , the Context Imager (CTX) 6 , and the High Resolution Imaging Science Experiment (HiRISE) 7 instruments on the Mars Reconnaissance Orbiter (MRO) resolve mineralogical, stratigraphic and geological relationships for phyllosilicate deposits. This combination of instruments permits mineralogical mapping at 18 m per pixel with CRISM linked with metre-scale geomorphology from CTX and HiRISE. We focus here on the stratigraphic setting of phyllosilicate-bearing rocks in three regions and report the detection of phyllosilicate in sedimentary settings.We identify two principal classes of mineral in the CRISM data on the basis of observed absorptions: Al phyllosilicates and the more common and spatially dominant Fe/Mg phyllosilicates. The increased spatial and spectral resolutions of CRISM have revealed a diversity of absorption band shapes, positions and combinations indicating variations in phyllosilicate type and composition ( Fig. 1; see Methods for processing and identification details). Most spectra show a band at ,1.4 mm from the overtone of the OH stretch, a strong 1.9-mm H 2 O band and absorptions near 2.28-2.30 mm (for example, spectrum 3 in Fig. 1b), which ...

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Section: Lettersmentioning

confidence: 99%

“…The Nili Fossae region shows expansive outcrops of phyllosilicates 2,12 but also extensive spectral signatures of olivine in close proximity [15][16][17][18][19] . Several high-resolution observations across this region (Fig.…”

mentioning

confidence: 99%

Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument

Mustard

Murchie

Pelkey

et al. 2008

Nature

657

517

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“…Therefore, further work should investigate whether similar kinds of collective interactions are operating in the low-diversity biofilms of Lost City chimneys, where survival in extreme conditions may require the stable coexistence of multiple phenotypes enabled by LGT. Lost City carbonate chimneys have been discussed as models for the origin and early evolution of life because of the prevalence of ultramafic environments on early Earth (Grove and Parman, 2004) and Mars (Hamilton and Christensen, 2005), because of the exothermic generation of hydrogen and organic compounds by serpentinization (Proskurowski et al, 2008), because of the potential of chimney pores to concentrate biochemicals (Baaske et al, 2007) and because of the advantage of a high pH for prebiotic chemistry (Martin et al, 2008). In addition, it has been suggested that a community of primitive precells (Baross and Hoffman, 1985) or progenotes (Woese, 1998) undergoing extensive gene transfer represented an early stage of evolution before the advent of free-living cells.…”

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confidence: 99%

Abundant transposases encoded by the metagenome of a hydrothermal chimney biofilm

2009

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The carbonate chimneys of the Lost City Hydrothermal Field on the Mid-Atlantic Ridge are coated in thick microbial biofilms consisting of just a few dominant species. We report a preliminary analysis of a biofilm metagenome that revealed a remarkable abundance and diversity of genes potentially involved in lateral gene transfer (LGT). More than 8% of all metagenomic reads showed significant sequence similarity to transposases; all available metagenomic data sets from other environments contained at least an order of magnitude fewer transposases. Furthermore, the sequence diversity of transposase genes in the biofilm was much greater than that of 16S rRNA genes. The small size and high sequencing coverage of contigs containing transposases indicate that they are located on small but abundant extragenomic molecules. These results suggest that rampant LGT among members of the Lost City biofilm may serve as a generator of phenotypic diversity in a community with very low organismal diversity. The ISME Journal (

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“…One of the main discoveries of the THEMIS instrument was the finding of wide expanses of olivine-rich rocks exposed at the surface. Because olivine is a mineral that is rapidly broken down in the presence of water, the occurrence of olivine implies that the climate of Mars was drier (and probably colder) than previously envisaged (Hamilton & Christensen 2005). Spectral analyses of Mars' surface have also been acquired by the Gamma Ray Spectrometer (GRS) aboard Odyssey.…”

Section: Water On Mars : Evidence From Spectroscopic Analysismentioning

confidence: 99%

WatSen: searching for clues for water (and life) on Mars

Grady

2006

International Journal of Astrobiology

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: There is plenty of evidence for fluid on Mars : large-scale (planet-wide) features have been captured over four decades by a procession of orbiting satellites equipped with cameras with increasingly higher spatial resolutions. Imagery of the surface shows channels, valleys, ice-caps, etc. Small-scale, more local evidence for fluid has come from images obtained by rovers on the Martian surface. Images that water produced many of the features are supported by spectroscopic measurements (again both planet-wide and local) over a range of wavelengths, which show the presence of minerals generally only produced in the presence of water (haemetite, jarosite, etc.). Results from meteorites continue this picture of fluid activity taking place over significant periods of Mars' history. Despite all these indicators of water, direct detection of water has never been performed. We have reviewed the evidence for water on Mars' surface, and have described WatSen, a combined humidity sensor and infrared IR detector, which can be employed to search for water at and below Mars' surface. WatSen is designed to be part of the suite of instruments on the mole that will be deployed as part of the Geophysics and Environment Package on ExoMars. The objectives of the package are as follows : (i) to detect water within Martian soil by measuring humidity and IR spectral characteristics of the substrate at surface and at depth ; (ii) to determine the mineralogy and mineral chemistry of surface soils (this measurement will provide the mineralogical context for the elemental results that come from other instruments mounted on the landing platform); (iii) to determine how mineralogy changes with depth. The utility of WatSen is that it will not only detect the presence of water, but will also be able to record which minerals are present and their chemistry ; it is also sensitive to many organic species. WatSen is a new instrument concept specifically designed to search for clues of the presence of water, and to look for evidence of life on Mars.

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Evidence for extensive, olivine-rich bedrock on Mars

Cited by 197 publications

References 13 publications

Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument

Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument

Abundant transposases encoded by the metagenome of a hydrothermal chimney biofilm

WatSen: searching for clues for water (and life) on Mars

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