Spectral Nature of CO2 Adsorption on Meteorites (original) (raw)
Related papers
From protoplanetary dust to asteroidal heating: a mineralogical study of the CO3 chondrites
2020
Carbonaceous chondrites are among the most primitive extra-terrestrial materials available for study. These meteorites provide a detailed record of the geological processes and events that have shaped our solar system over the last 4.5 billion years. "Ornans-like" carbonaceous chondrite meteorites, also referred to as CO3 chondrites, comprise pristine, primitive mineralogy that has undergone no or minimal aqueous alteration. CO3 chondrites are also known to contain up to 3.5% carbon in the form of insoluble and soluble organic matter, graphite and carbonates. The CO3 chondrites form a suite of samples that have experienced increasing degrees of thermal metamorphism, from weakly heated CO3.0s such as Colony and DOM 08006, to strongly meta-morphosed CO3.8s such as Isna. Detailed studies of this suite of CO3 chondrites enables firstly a determination of the most primitive and earliest formed aggregates of crystalline, amorphous and organic solids, and their textural relations...
Spectroscopic comparison of aqueous altered asteroids with CM2 carbonaceous chondrite meteorites
Astronomy and Astrophysics Supplement Series, 1999
In the last year we have started a spectroscopic investigation of asteroids located in the region of the mainbelt between about 2.2 and 3.6 AU. The aim of this work is to study the aqueous alteration process which acted in that zone, dominated by low albedo C-type asteroids, and to compare the spectra of these hydrous objects with those of CM2 carbonaceous chondrite meteorites. In fact, the spectra of these meteorites reveal features probably due to aqueous altered materials on their surfaces. The study of the aqueous alteration process can give important information on the chemical and thermal evolution of the earliest Solar System. More that 65% of the investigated objects have revealed features suggesting the presence of hydrous materials. The comparison of the spectra of the hydrated asteroids obtained to date with those of several CM2 carbonaceous chondrite meteorites seems to indicate that aqueous altered asteroids could be the parents of CM2 meteorites. The data have been obtained during several observational runs at the Asiago Observatory with the 1.8 m telescope and at ESO-LaSilla with the 1.5 m telescope.
The Astrophysical Journal, 2008
We report the mineralogy, petrography, as well as oxygen and magnesium isotope data of a newly identified FUN inclusion from the CV carbonaceous chondrite NWA 779. Variability in the texture of the mineral phases coupled with oxygen isotope data provides evidence for multistage evolution of this inclusion under distinct thermal regimes: slow crystallization of 16 O-rich melt accompanied by evaporation, and subsequent remelting in an 16 O-poor reservoir during transient heating events, possibly associated with the formation of CV chondrules. The inferred oxygen isotope composition of the precursor material of this inclusion (‰) is consistent with that observed for 17,18 ϩ2.5 d O p Ϫ48.4 Ϫ3.0 CAIs and amoeboid olivine aggregates from least metamorphosed carbonaceous chondrites, suggesting that both FUN and normal CAIs formed in an 16 O-rich reservoir with oxygen isotope composition similar to that inferred for the Sun. However, in contrast to normal CAIs, most FUN inclusions show no evidence for live 26 Al at the time of their formation. Based on these observations, we propose that the protosolar molecular cloud was polluted with stellarderived 26 Al prior to its collapse. Thus, FUN CAIs formed at a time when dust inherited from the molecular cloudincluding the carrier of 26 Al-was still poorly homogenized in the protoplanetary disk.
Icarus, 2012
We examined the spectral reflectance properties of 16 CO-type carbonaceous chondrites (CCs) in order to better understand their range of spectral properties, develop spectral-compositional correlations, and provide information that may aid in the search for CO parent bodies. As a group, our CO powder spectra have some similarities and differences. COs have experienced varying degree of thermal metamorphism, with petrologic subgrades ranging from CO3.0toCO3.0 to CO3.0toCO3.8. Their reflectance spectra are characterized by a ubiquitous absorption feature in the 1 lm region, and a nearly ubiquitous feature in the 2 lm region that appears in CO >3.1 spectra. The 1 lm region feature is attributable to abundant Fe-bearing amorphous phases (and Fe-poor olivine) in the lower petrologic subtypes, which gradually transforms to more abundant and Fe-rich olivine with increasing metamorphism. The increase in depth and decrease in wavelength position of this feature are consistent with this transformation.
Detection of carbonates in dust shells around evolved stars
Nature, 2002
Carbonates on large Solar System bodies like Earth and Mars 1,2 (the latter represented by the meteorite ALH84001) form through the weathering of silicates in a watery (CO 3 ) 2solution. The presence of carbonates in interplanetary dust particles and asteroids (again, represented by meteorites) is not completely understood, but has been attributed to aqueous alteration on a large parent body, which was subsequently shattered into smaller pieces. Despite efforts 3±5 , the presence of carbonates outside the Solar System has hitherto not been established 6,7 . Here we report the discovery of the carbonates calcite and dolomite in the dust shells of evolved stars, where the conditions are too primitive for the formation of large parent bodies with liquid water. These carbonates, therefore, are not formed by aqueous alteration, but perhaps through processes on the surfaces of dust or ice grains or gas phase condensation. The presence of carbonates which did not form by aqueous alteration suggests that some of the carbonates found in Solar System bodies no longer provide direct evidence that liquid water was present on large parent bodies early in the history of the Solar System 8 .
Space Science Reviews, 2019
Protoplanetary disks are dust-rich structures around young stars. The crystalline and amorphous materials contained within these disks are variably thermally processed and accreted to make bodies of a wide range of sizes and compositions, depending on the heliocentric distance of formation. The chondritic meteorites are fragments of relatively small and undifferentiated bodies, and the minerals that they contain carry chemical signatures providing information about the early environment available for planetesimal formation. A current hot topic of debate is the delivery of volatiles to terrestrial planets, understanding that they were built from planetesimals formed under far more reducing conditions than the primordial carbonaceous chondritic bodies. In this review, we describe significant evidence for the accretion of ices and hydrated minerals in the outer protoplanetary disk. In that distant region highly porous and fragile carbon and water-rich transitional asteroids formed, being the parent bodies of the carbonaceous chondrites (CCs). CCs are undifferentiated meteorites that never melted but experienced other physical processes including thermal and aqueous alteration. Recent evidence indicates that few of them have escaped significant alteration, retaining unique features that can be interpreted as evidence of wet accretion. Some examples of carbonaceous chondrite parent body aqueous alteration will be presented. Finally, atomistic interpretations of the first steps leading to water-mediated alteration during the accretion of CCs are provided and discussed. From these new insights into the water retained in CCs we can decipher the pathways of delivery of volatiles to the terrestrial planets.
FD 168: Exploring the Origins of Carbon in Terrestrial Worlds
Faraday Discussions, 2014
Given the central role of carbon in the chemistry of life, it is a fundamental question as to how carbon is supplied to the Earth, in what form and when. We provide an accounting of carbon found in solar system bodies, in particular a comparison between the organic content of meteorites and that in identified organics in the dense interstellar medium (ISM). Based on this accounting identified organics created by the chemistry of star formation could contain at most ∼15% of the organic carbon content in primitive meteorites and significantly less for cometary organics, which represent the putative contributors to starting materials for the Earth. In the ISM ∼ 30% of the elemental carbon is found in CO, either in the gas or ices, with a typical abundance of ∼ 10 −4 (relative to H 2). Recent observations of the TW Hya disk find that the gas phase abundance of CO is reduced by an order of magnitude compared to this value. We explore a solution where the volatile CO is destroyed via a gas phase processes, providing an additional source of carbon for organic material to be incorporated into planetesimals and cometesimals. This chemical processing mechanism requires warm grains (> 20 K), partially ionized gas, and sufficiently small (a grain < 10 µm) grains, i.e. a larger total grain surface area, such that freeze-out is efficient. Under these conditions static (non-turbulent) chemical models predict that a large fraction of the carbon nominally sequestered in CO can be the source of carbon for a wide variety of organics that are present as ice coatings on the surfaces of warm pre-planetesimal dust grains.
Primodial retention of carbon by the terrestrial planets
Icarus, 1979
Chemical equilibrium calculations on the stability of pure and dissolved graphite and cohenite (Fe3C), several other carbides, and several carbonates have been carried out for a system with solar elemental abundances over a very wide range of temperature and pressure. The calculated abundances of condensed carbon compounds are similar to the observed inventories on Earth and Venus, but fully 10 times smaller than the minimum carbon abundance found in ordinary chondrites. The total carbon content of most iron meteorites is compatible with their origin as a cooling Fe-Ni-C-S-P solution which was saturated with dissolved carbon at the solidus, such as would be produced by melting an ordinary chondrite, not by direct condensation from or equilibrium with the primitive solar nebula. It is argued that the carbon content of Mars need not be appreciably greater than that of the Earth. Material with even lower formation temperatures than Mars, such as the primitive material in the asteroid belt, may retain substantially more carbon as disequilibrium polymeric organic matter, possibly by the Fischer-Tropsch mechanism favored by Anders. Carbonates are not found as equilibrium products in a solar-composition system, and are probably secondary alteration products. CaCO3 might, however, persist in a solar-composition gas at temperatures below 460°K and pressures below 10-~.e bar. The most stable condensed carbon compounds are found to be graphite, Fe3C, and possibly TiC, all in solid solution in the metal phase.
Geochimica Et Cosmochimica Acta, 2010
The mineralogy and bulk compositions of the matrices of the CR chondrites MET 00426 and QUE 99177 have been studied using a combination of SEM, EPMA, and TEM techniques. The matrices of these two chondrites are texturally, chemically, and mineralogically similar and are characterized by significant FeO-enrichments with respect to other CR chondrite matrices, nearly flat refractory lithophile patterns, variable volatile element patterns, and a simple mineral assemblage dominated by amorphous silicate material and Fe,Ni sulfides. Fine-grained, crystalline silicate phases such as olivine and pyroxene appear to be extremely rare in the matrices of both meteorites. Instead, the mineralogy of matrices and fine-grained rims of both meteorites consists of abundant amorphous FeO-rich silicate material, containing nanoparticles of Fe,Ni sulfides (troilite, pyrrhotite, and pentlandite). Secondary alteration minerals that are characteristic of other CR chondrites (e.g., Renazzo and Al Rais), such as phyllosilicates, magnetite, and calcite are also rare. The texture and mineralogy of the matrices of MET 00426 and QUE 99177 share many features with matrices in the primitive carbonaceous chondrites ALH A77307 (CO3.0) and Acfer 094 (unique). These observations show that MET 00426 and QUE 99177 are very low petrologic type 3 chondrites that have escaped the effects of aqueous alteration, unlike other CR chondrites, which are typically classified as petrologic type 2. We suggest that these meteorites represent additional samples of highly primitive, but extremely rare carbonaceous chondrites of petrologic type 3.00, according to the classification scheme of Grossman and Brearley (2005). The highly pristine nature of MET 00426 and QUE 99177 provides important additional insights into the origins of fine-grained materials in carbonaceous chondrites. Based on our new observations, we infer that the amorphous silicate material and nanosulfide particles that dominate the matrices of these meteorites formed in the solar nebula by rapid condensation of material following high-temperature events, such as those that formed chondrules.