Jezero crater is the landing site for the Mars 2020 Perseverance rover. The Noachian‐aged crater has undergone several periods of fluvial and lacustrine activity and phyllosilicate‐ and ...carbonate‐bearing rocks were formed and emplaced as a result. It also contains a portion of the regional Nili Fossae olivine‐carbonate unit. In this work, we performed spectral mixture analysis of visible/near‐infrared hyperspectral imagery over Jezero. We modeled carbonate abundances up to ∼35% and identified three distinct units containing different carbonate phases. Our work also shows that the olivine in Jezero is predominantly restricted to aeolian deposits overlying the carbonate rocks. The diversity of carbonate phases in Jezero points to multiple periods of carbonate formation under varying conditions.
Plain Language Summary
Jezero crater is the landing site for the Mars 2020 Perseverance rover. The site was selected due to the identification of many minerals that formed in lakes and rivers throughout the crater's history and that may have kept a record of potential biological life. Previous studies have identified a variety of these kinds of minerals, such as phyllosilicates and carbonates, but have not determined how much of each kind of mineral is present in Jezero at this scale. In this work, we performed an analysis to model the abundance of these minerals in three orbital images, focusing in particular on the abundances of three different carbonates with different compositions. The diversity of carbonates in Jezero points to multiple periods of carbonate formation under varying conditions.
Key Points
Unmixing of near‐infrared spectra in Jezero crater suggests carbonate abundances up to ∼35% per pixel
Strong olivine spectral signatures are correlated to sand deposits overlying light‐toned carbonate‐bearing rocks
Fe‐carbonate is the dominant phase throughout the study area; Mg‐carbonate is present along the Jezero paleolake rim
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Parent body thermal metamorphism is an important process that alters the structure of organic matter in the parent asteroid of meteorites. Increasing and progressing thermal metamorphism results in ...carbonization and graphitization of carbonaceous matter in the parent body. Such modifications in the carbon structures can be studied by Raman microspectroscopy, thanks to its high sensitivity to structure and bonding within carbonaceous molecules. We have characterized polyaromatic carbonaceous matter in a total of 24 Antarctic CV3 and CO3 chondrites using micro-Raman imaging spectroscopy in an effort to better understand parent body thermal metamorphism and assess its effects on the carbon structures. Raman spectral parameters of the first-order carbon peaks (D and G) were extracted from at least 200 spectra for each meteorite and were compared to deduce relationships that yield information regarding the thermal metamorphism conditions. We also show, for the first time, spectral trends and relations of the second-order carbon peaks (2D and D+G) within the 2500-3200 cm-1 with thermal metamorphic history. The second-order peaks appear to contain information that is lacking in the first-order peaks. Based on the second-order carbon peak parameters, we tentatively classify four CV3 chondrites into subtypes, and reclassify another. Peak metamorphic temperatures of the investigated meteorites have been estimated based on the width of the D band as well as the calculated Raman spectral curvature. Estimated temperatures appear to correlate well with the assigned petrologic types. We have calculated higher peak metamorphic temperatures for the CV3 chondrites than for the considered CO3 chondrites and further showed that the peak metamorphic temperatures of CV3oxA chondrites are higher than those of CV3oxB, indicating possibly different metamorphic conditions for the two oxidized subtypes. We observe that there is a relatively larger temperature increase going from CO3.2 to CO3.4 (150°C increase) compared to CO3.4-CO3.6 (20°C), which may indicate that the graphitization and structural ordering of carbon reach a critical temperature regime around petrologic type CO3.3.
Abstract
Meteorites contain organic matter that may have contributed to the origin of life on Earth. Carbonyl compounds such as aldehydes and carboxylic acids, which occur in meteorites, may be ...precursors of biologically necessary organic materials in the solar system. Therefore, such organic matter is of astrobiological importance and their detection and characterization can contribute to the understanding of the early solar system as well as the origin of life. Most organic matter is typically sub-micrometer in size, and organic nanoglobules are even smaller (50–300 nm). Novel analytical techniques with nanoscale spatial resolution are required to detect and characterize organic matter within extraterrestrial materials. Most techniques require powdered samples, consume the material, and lose petrographic context of organics. Here, we report the detection of nanoglobular aldehyde and carboxylic acids in a highly primitive carbonaceous chondrite (DOM 08006) with ~ 20 nm spatial resolution using nano-FTIR spectroscopy. Such organic matter is found within the matrix of DOM 08006 and is typically 50–300 nm in size. We also show petrographic context and nanoscale morphologic/topographic features of the organic matter. Our results indicate that prebiotic carbonyl nanoglobules can form in a less aqueous and relatively elevated temperature-environment (220–230 °C) in a carbonaceous parent body.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Diviner Lunar Radiometer Experiment surface-temperature maps reveal the existence of widespread surface and near-surface cryogenic regions that extend beyond the boundaries of persistent shadow. The ...Lunar Crater Observation and Sensing Satellite (LCROSS) struck one of the coldest of these regions, where subsurface temperatures are estimated to be 38 kelvin. Large areas of the lunar polar regions are currently cold enough to cold-trap water ice as well as a range of both more volatile and less volatile species. The diverse mixture of water and high-volatility compounds detected in the LCROSS ejecta plume is strong evidence for the impact delivery and cold-trapping of volatiles derived from primitive outer solar system bodies.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Ungrouped carbonaceous chondrites are not easily classified into one of the well‐established groups due to compositional/petrological differences and geochemical anomalies. Type 2 ungrouped ...carbonaceous chondrites represent a very small fraction of all carbonaceous chondrites. They can potentially represent different aspects of asteroids and their regolith material. By conducting a multitechnique investigation, we show that Queen Alexandra Range (QUE) 99038 and Elephant Moraine (EET) 83226 do not resemble type 2 carbonaceous chondrites. QUE 99038 exhibits coarse‐grained matrix, Fe‐rich rims on olivines, and an apparent lack of tochilinite, suggesting that QUE 99038 has been metamorphosed. Its polyaromatic organic matter structures closely resemble oxidized CV3 chondrites. EET 83226 exhibits a clastic texture with high porosity and shows similarities to CO3 chondrites. It consists of numerous large chondrules with fine‐grained rims that are often fragmented and discontinuous and set within matrix, suggesting a formation mechanism for the rims in a regolith environment. The kind of processes that can result in such chemical compositions as in QUE 99038 and EET 83226 is currently not fully known and clearly presents a conundrum. Tarda is a highly friable carbonaceous chondrite with close resemblance to Tagish Lake (ungrouped C2 chondrite). It comprises different types of chondrules (some with Fe‐rich rims), framboid magnetite, sulfides, carbonates, and phyllosilicate‐ and carbon‐rich matrix, and is consistent with being an ungrouped C2 chondrite.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
► We report TIR and NIR spectra of calcined clays and natural zeolites. ► IR spectral changes with heating are affected by samples’ thermal reactions. ► IR spectral changes with heating are affected ...by the type of octahedral cations. ► Some heated clays may lose their TIR spectral features while keeping their NIR bands.
Most phyllosilicates on Mars appear to be associated with ancient terrains. As such, they may have experienced shock heating produced by impacts and could have been significantly altered or melted. We characterized the effects of high temperatures on the mid-to-far-infrared (mid-to-far-IR) emission (100–1400cm−1; 7.1–100μm) and near-infrared (NIR) reflectance (1.2–2.5μm) spectra of phyllosilicates by measuring experimentally calcined (100–900°C) phyllosilicates and also two zeolites. Correlated differential scanning calorimetry (DSC) measurements were also performed on each sample to provide insight into the thermal activities of the phyllosilicates and natural zeolites. Our results indicate that all phyllosilicates exhibit characteristic degradations in both NIR and mid-to-far-IR spectral properties between 400 and 800°C, mainly attributable to the dehydroxylation and recrystallization processes as temperature increases. Spectral features of natural zeolites persist to higher temperatures compared to features of phyllosilicates during heating treatments. The thermal behaviors of phyllosilicate infrared (IR) properties are greatly influenced by the compositions of the octahedral cations: (1) changes in both the NIR and mid-to-far-IR spectra of phyllosilicates tend to occur at lower temperatures (300–400°C) in the Fe3+-rich samples as compared to the Al3+-rich types (400–600°C); (2) Mg2+-trioctahedral phyllosilicates hectorite, saponite, and sepiolite all display major mid-to-far-IR spectral changes at 700°C, corresponding to the formation of enstatite; (3) phyllosilicates that have minor replacement of Mg2+ for Al3+ in octahedral positions (e.g. cheto-type montmorillonite and palygorskite) show an absorption band at ∼920cm−1 that becomes strong at 900°C. Inconsistency between spectral behaviors in the mid-to-far-IR and NIR regions is also discussed for phyllosilicates. Results from this study have provided suggestive evidence for the scenario that some phyllosilicates could lose all original spectral features in mid-to-far-IR region while maintaining their characteristic hydration bands in NIR region in the same temperature range.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Thermal infrared spectra of the martian surface indicate the presence of small concentrations (~2 to 5 weight %) of carbonates, specifically dominated by magnesite (MgCO3). The carbonates are widely ...distributed in the martian dust, and there is no indication of a concentrated source. The presence of small concentrations of carbonate minerals in the surface dust and in martian meteorites can sequester several bars of atmospheric carbon dioxide and may have been an important sink for a thicker carbon dioxide atmosphere in the martian past.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Carbonaceous chondrites are among the most primitive meteorites that escaped extreme temperatures and melting in their parent bodies and, as such, offer valuable records of the parent body origins, ...formation, and evolution. The presence of organic molecules and carbonaceous phases make CM chondrites invaluable as they may have contributed prebiotic material to early Earth. Fine-grained rims (FGRs) and organic-rich dark clasts are particularly interesting features, the origin, formation, and evolution of which are not fully understood. In this study, we aimed to characterize several FGRs and dark clasts in two CM2 chondrites, Aguas Zarcas and Jbilet Winselwan, using backscattered electron images, confocal micro-Raman spectroscopy, and nanoscale near-field infrared imaging and spectroscopy. The nano-FTIR spectra show that the dark clasts and FGRs are chemically heterogeneous at a submicron scale and those of Aguas Zarcas are composed of organics (such as aliphatics, aromatics, and carbonyls) as well as alteration phases (such as phyllosilicates, carbonates, and sulfates). The FGRs are compositionally almost identical and exhibit heterogeneous alteration as well as a lack of fragmentation. The thicknesses of FGRs positively correlate with the enclosed chondrule diameter regardless of the chondrule type. The samples appeared to have experienced minimal brecciation after the chondrules were surrounded by the FGRs. These observations suggest nebular origin for the FGRs. The presence of organics embedded within these FGRs may further indicate that they may have formed in the solar nebula as well. In comparison, Jbilet Winselwan contains relatively less organics and exhibits more thermally metamorphosed mineralogy and matrix textures. These features could be the result of short-duration heating, such as impact heating, which also likely caused shock and dehydration/decomposition of the hydrated phases.
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IJS, KILJ, NUK, PNG, UL, UM
9.
Highly Silicic Compositions on the Moon Glotch, Timothy D; Lucey, Paul G; Bandfield, Joshua L ...
Science (American Association for the Advancement of Science),
09/2010, Volume:
329, Issue:
5998
Journal Article
Peer reviewed
Using data from the Diviner Lunar Radiometer Experiment, we show that four regions of the Moon previously described as "red spots" exhibit mid-infrared spectra best explained by quartz, silica-rich ...glass, or alkali feldspar. These lithologies are consistent with evolved rocks similar to lunar granites in the Apollo samples. The spectral character of these spots is distinct from surrounding mare and highlands material and from regions composed of pure plagioclase feldspar. The variety of landforms associated with the silicic spectral character suggests that both extrusive and intrusive silicic magmatism occurred on the Moon. Basaltic underplating is the preferred mechanism for silicic magma generation, leading to the formation of extrusive landforms. This mechanism or silicate liquid immiscibility could lead to the formation of intrusive bodies.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Granites are nearly absent in the Solar System outside of Earth. Achieving granitic compositions in magmatic systems requires multi-stage melting and fractionation, which also increases the ...concentration of radiogenic elements
. Abundant water and plate tectonics facilitate these processes on Earth, aiding in remelting. Although these drivers are absent on the Moon, small granite samples have been found, but details of their origin and the scale of systems they represent are unknown
. Here we report microwave-wavelength measurements of an anomalously hot geothermal source that is best explained by the presence of an approximately 50-kilometre-diameter granitic system below the thorium-rich farside feature known as Compton-Belkovich. Passive microwave radiometry is sensitive to the integrated thermal gradient to several wavelengths depth. The 3-37-gigahertz antenna temperatures of the Chang'e-1 and Chang'e-2 microwave instruments allow us to measure a peak heat flux of about 180 milliwatts per square metre, which is about 20 times higher than that of the average lunar highlands
. The surprising magnitude and geographic extent of this feature imply an Earth-like, evolved granitic system larger than believed possible on the Moon, especially outside of the Procellarum region
. Furthermore, these methods are generalizable: similar uses of passive radiometric data could vastly expand our knowledge of geothermal processes on the Moon and other planetary bodies.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
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