Hydrogen diffusion in major hydrous minerals determines the closure temperatures of isotopic exchange used to track fluid-rock interactions. Deuterium-hydrogen (D-H) exchange was experimentally investigated between minerals and deuterated gas (D-2) in an ambient-pressure furnace over the temperature range of 400-650 degrees C (tremolite, vesuvianite) and between minerals and D2O at high pressure (1.5-3 GPa) and temperature (315-500 degrees C) in a belt press (glaucophane, epidote). D / (D + H) ratios in exchanged mineral grains were mapped using Raman spectroscopy calibrated by comparison with NanoSIMS analyses. Diffusion coefficients constrained by isotopic profiles were fitted to the Arrhenius equation D-D / H = D(0)e(a)((-H)/RT), where H-a is the activation enthalpy, and D-0 is the diffusion coefficient at infinite temperature T. The validity of intracrystalline diffusion laws from the literature is discussed with respect to the mechanical properties of hydrous minerals. Diffusion in tremolite is affected by intense cleavage, which reduces the effective grain size relative. High pressure appears to suppress cleavage opening in glaucophane. Results suggest that plasticity counteracts grain size reductions along cleavage planes in phyllosilicates. For vesuvianite, which lacks cleavage planes, intracrystalline diffusion is a valid assumption. In epidote, diffusivities are scattered over several orders of magnitude. Closure temperatures for hydrogen isotope diffusion were calculated and indicate that vesuvianite and phyllosilicates can record fluid-rock interactions under regional metamorphic conditions. Amphiboles may retain information about relatively short-lived eruptive events. Spatially resolved measurements of hydrogen isotopic compositions in those minerals may reveal low-temperature (100 < T < 400 degrees C) fluid-rock interactions associated with slip along major faults and metamorphic terrane exhumation.

Carbonaceous chondrites contain up to 4 wt% organic matter, likely inherited from precursors synthesised during preaccretion events. This organic inventory was later altered by hydrothermal and radiative processes, though the role of shock-induced impacts remains unclear. In this study, we examine the solid-state mechanochemical reactivity of hexamethylenetetramine (HMT) with sodium-rich montmorillonite (MMT) as an analogue to investigate the influence of shock- or impact-induced processes on organic matter evolution. HMT is reactive under mechanical stress, particularly when the clay mineral structure is disrupted, resulting in a wide range of molecules, including HMT-related compounds (as HMT-CH3, HMT-OH, among others), pyrazine and triazinane/triazine derivatives. Notably, the incorporation of oxygen in N-rich species was also observed, despite the absence of liquid water. Conversely, when the clay mineral remains intact, mechanical input promotes the solid-state insertion of HMT-like molecules (as HMT, HMT-CH3 and triazinane derivative) within its interlayer space, thereby protecting it from further reaction. The “cyclic mechanical input” delivered by laboratory milling (i.e., MM 200) and grinding (i.e., McCrone) is relevant to shock processes at an asteroid surface through repeated micrometeorite and IDPs impacts (i.e., space gardening). This work highlights shock/impact as a key factor driving both transformation and protection of extraterrestrial organics, offering new insights on how impact processes might have shaped extraterrestrial organic matter and consequent exogenous delivery of possibly prebiotic compounds to planetary surfaces.

Amino acids have been detected in carbonaceous chondrites, with abundances and isotopic compositions varying significantly between different meteorites as well as within individual meteorites. In this study, we assessed whether the presence and abundance of Fe-rich phases during parent body alteration can account for observed variations in amino acid concentrations and isotope composition. To test this, we examined the chemical and 13C-isotopic signatures of six amino acids-glycine, beta-alanine, alpha-alanine, 2-aminoisobutyric acid, gamma-aminobutyric acid, and isovaline-following experimental exposure to hydrothermal conditions (150 degrees C, 10 days) in the presence or absence of Fe-bearing materials (Fe, Fe2O3, FeS2). In the absence of Fe-rich materials, glycine and alpha-alanine rather withstood hydrothermal conditions, consistently with abundances reported for carbonaceous chondrites having experienced various degrees of aqueous alteration. In contrast, upon exposure to similar hydrothermal conditions, the degradation of beta-alanine produced a new compound, possibly 3-aminoadipic acid, via the recombination of products of its decarboxylation and deamination, while more than 95% of gamma-aminobutyric acid was converted to 2-pyrrolidone through self-cyclization. The presence of Fe-rich materials inhibited the destruction of beta-alanine, 2-aminoisobutyric acid, and gamma-aminobutyric acid. Fe2O3 promoted the conversion of glycine into aspartic acid, and the resulting organics interacted with Fe2O3, leading to a relatively higher organic content in the residues compared to other Fe-containing materials after the experiments. Oxides in CI chondrites may exhibit variable effects on each amino acid compound during aqueous alteration, potentially explaining the higher beta-Alanine/Glycine ratios observed compared with CM chondrites. The slight changes in delta 13C values of amino acids upon exposure to hydrothermal conditions, independent of the presence or absence of Fe-rich materials, could not account for the variations observed in the delta 13C values of chondritic amino acids. Hence, the delta 13C values of amino acids reported in CR and CM chondrites may be inherited from the preaccretion processes.

In order to use black crusts as archives of ancient air pollution, it is necessary to understand how they form and identify their growth direction. Two main processes have been proposed in the literature: outward progression by the diffusion and reaction of Ca2+ with SO42- in the water film at the outer surface, and/or inward progression by pseudomorphosis, whereby calcite is replaced by gypsum. To clarify these mechanisms, simulation chamber experiments were designed to evaluate the growth rate of gypsum on pristine limestone slabs, and then to alter old black crusts using 34S-marked SO2 and O3 at 100 % relative humidity (RH). NanoSIMS imaging revealed areas enriched in 34S on the outer surface, suggesting an outward growth of gypsum in these experimental conditions. The extrapolation of these results to field observations is discussed. However, they are key to interpreting the pollution recorded in monument black crusts.

To protect and preserve the bronze bells, which represent an ancient and modern multicultural heritage, one needs to understand precisely how they have changed over time. A comparative study of the corrosion facies that developed on the internal and external profiles of a bell exposed to an urban atmosphere for 90 years was conducted. In addition, this corrosion was compared to that of a bell exposed to a marine atmosphere for an equivalent amount of time. An original D218O-labeled atmosphere re-corrosion protocol and mass nanospectrometry analysis were used to study the microinfiltration properties of the urban patina. Chlorine aerosols of anthropogenic origin penetrate the urban patina of copper oxi-sulfate and silicate elements differently. On the inside of the bell, atacamite forms on the surface, whereas on the outside, a copper oxi-chloride layer develops next to the alloy. Considering the influence of dissolved oxygen and chlorine in the patina, selective pitting corrosion occurs in the α-phase alloy: On the inner profile of the bell Type-II stratified corrosion facies (layers of copper oxi-sulfate and tin oxi-chlorides) appear. They contrast with the Type-I uniform corrosion (copper and tin oxides with traces of sulfur) with corroded interdendritic cracks of mechanical origin (copper/lead oxides) of the outer profile. The difference with the α/δ-pitting corrosion that forms under a marine atmosphere could be explained by different corrosion kinetics linked to the environmental conditions and bell profiles. In terms of microinfiltration properties, the urban patina acts as a selective barrier. D and 18O are adsorbed into the pores and microcracks. The copper oxi-chloride layer blocks the penetration of D and S, but allows 18O to diffuse into the alloy. At the alloy/corroded α-phase interface, the development of cuprite is caused by anodic/cathodic corrosion reaction involving 18O. In absence of the copper oxi-chloride film, D is responsible for the dissolution and precipitation process of antlerite in α-laminated corrosion products. 18O precipitates at the interface of corroded α-phase strata.

Chondritic meteorites (chondrites) contain evidence for the interaction of liquid water with the interiors of small bodies early in Solar System history. Here we review the processes, products and timings of the low-temperature aqueous alteration reactions in CR, CM, CI and ungrouped carbonaceous chondrites, the asteroids Ryugu and Bennu, and hydrated dark clasts in different types of meteorites. We first consider the nature of chondritic lithologies and the insights that they provide into alteration conditions, subdivided by the mineralogy and petrology of hydrated chondrites, the mineralogy of hydrated dark clasts, the effects of alteration on presolar grains, and the evolution of organic matter. We then describe the properties of the aqueous fluids and how they reacted with accreted material as revealed by physicochemical modelling and hydrothermal experiments, the analysis of fluid inclusions in aqueously formed minerals, and isotope tracers. Lastly, we outline the chronology of aqueous alteration reactions as determined using the 53Mn-53Cr and 129I-129Xe systems.

Metasomatism refers to the process during which a pre-existing rock undergoes compositional and mineralogical transformations associated with chemical reactions triggered by the reaction of fluids which invade the protolith. It changes chemical compositions of minerals, promotes their dissolution and precipitation of new minerals. In this paper, we review metasomatic alteration of type 3 ordinary (H, L, LL) and carbonaceous (CV, CO, CK) chondrites, including (i) secondary mineralization, (ii) physicochemical conditions, (iii) chronology (53Mn-53Cr, 26Al-26Mg, 129I-129Xe) of metasomatic alteration, (iv) records of metasomatic alteration in H, O, N, C, S, and Cl isotopic systematics, (v) effects of metasomatic alteration on O- and Al-Mg-isotope systematics of primary minerals in chondrules and refractory inclusions, and (vi) sources of water ices in metasomatically altered CV, CO, and ordinary chondrites, and outline future studies.

Amino acids detected in carbonaceous chondrites are commonly enriched in heavy isotopes of hydrogen compared to terrestrial counterparts. This is interpreted as the consequence of synthesis processes happening in cold extraterrestrial environments. However, the magnitude of this enrichment is variable among classes of chondrites and among individual amino acid in a given chondrite. In this study, we investigated the evolution of the D/H isotope ratio of amino acids experimentally exposed to pure D2O at 150 degrees C. We observed that not all the hydrogen-specific sites are prone to deuterium-hydrogen exchange under hydrothermal conditions. Ab-initio modeling pinpoints the higher acidity of the carbon in alpha position (C alpha) leading to a site-specific preferential DH exchange, affecting the hydrogen atoms bonded to C alpha (alpha-H). This explains the low exchange rate of 2-aminoisobutyric acid and isovaline, these branched amino acids lacking alpha-H, and the rather high exchange rate of glycine, alpha-alanine and beta-alanine, their alpha-H exchanging faster. By extrapolating these results, it can be assumed that chondritic amino acids lacking alpha-H and containing only primary hydrogen (i.e., -CH3 group) have better retained their pre-accretional D/H values despite hydrothermal alteration on the parent body.

The study aims to develop and optimise a derivatisation strategy to combine gas and liquid chromatography analysis of a single sample. Silylation was selected for gas chromatography analysis, as it increases the volatility and detectability of biologically related molecules. Deprotection of tert-butyldimethylsilyl derivatives was performed, enabling efficient conversion into the native molecular sample for further analysis using sensitive hyphenated techniques, thereby broadening the target scope. The deprotection reaction proceeded simply and rapidly using water and methanol at room temperature. The absolute configuration of chiral molecules was preserved throughout the procedure. No significant molecular loss or analytical bias was observed. This new strategy was applied to samples of astrobiological interest to provide both a broad molecular mapping and detailed data on indigenous compounds by decreasing misinterpretation. Application to meteoritic samples highlighted the efficacy and relevance of the proof of concept.

We report the H, C, and N isotopic compositions of microscale (0.2 to 2 mu m) organic matter in samples of asteroid Ryugu and the Orgueil CI carbonaceous chondrite. Three regolith particles of asteroid Ryugu, returned by the Hayabusa2 spacecraft, and several fragments of Orgueil were analyzed by NanoSIMS isotopic imaging. The isotopic distributions of the Ryugu samples from two different collection spots are closely similar to each other and to the Orgueil samples, strengthening the proposed Ryugu-CI chondrite connection. Most individual sub-mu m organic grains have isotopic compositions within error of bulk values, but 2-10 % of them are outliers exhibiting large isotopic enrichments or depletions in D, 15N, and/or 13C. The H, C and N isotopic compositions of the outliers are not correlated with each other: while some organic grains are both D- and 15N-enriched, many are enriched or depleted in one or the other system. This most likely points to a diversity in isotopic fractionation pathways and thus diversity in the local formation environments for the individual outlier grains. The observation of a relatively small population of isotopic outlier grains can be explained either by escape from nebular and/or parent body homogenization of carbonaceous precursor material or addition of later isotopic outlier grains. The strong chemical similarity of isotopically typical and isotopically outlying grains, as reflected by synchrotron x-ray absorption spectra, suggests a genetic connection and thus favors the former, homogenization scenario. However, the fact that even the least altered meteorites show the same pattern of a small population of outliers on top of a larger population of homogenized grains indicates that some or most of the homogenization occurred prior to accretion of the macromolecular organic grains into asteroidal parent bodies.

In interplanetary bodies, organics are found originating from various environments. We replicate the solid-phase conditions in a laboratory to elucidate the step-by-step evolution of organic matter, spanning from dense molecular cloud ices to processes occurring within meteorite parent bodies. The focus of our work is on amino acids, considered as potential chemical tracers of secondary alteration on asteroids. Using gas chromatography and high-resolution mass spectrometry, trace amounts of amino acids are identified in a preaccretional organic analogue formed from a dense molecular ice analogue. This analogue was subsequently exposed to aqueous alteration. This induced an increase in the formation of alpha- and beta-amino acids over time. Supported by high-resolution mass spectrometry data, the reactions involved sugars and amine compounds, followed by amino acid destruction due to the Maillard reaction, which consumes both sugars and amino acids. Surprisingly, a second phase of amino acid formation, specifically alpha-amino acids, was observed, indicating the potential occurrence of the Strecker reaction. We demonstrate the intricate chemical network occurring within the presence of molecular diversity, similar to what might occur during parent body alteration. Therefore, investigations on reactivity within meteorite parent bodies have to take into account their molecular diversity, recognizing potential cross-reactions, as demonstrated in this work.

Context . The JAXA Hayabusa2 mission returned well-preserved samples collected from the carbonaceous asteroid Ryugu, providing unique non-terrestrially weathered samples from a known parent body. Aims . This work aims to provide a better understanding of the formation and evolution of primitive asteroidal matter by studying the fine scale association of organic matter and minerals in Ryugu samples. We characterized the samples by IR nanospectroscopy using infrared photothermal nanospectroscopy (AFM-IR) technique. This technique overcomes the diffraction limit (of several microns) of conventional infrared microspectroscopy (µ-FTIR). The samples were mapped in the mid-IR range at a lateral spatial resolution about a hundred times better than with µ-FTIR. This provided us with unique in situ access to the distribution of the different infrared signatures of organic components at the sub-micron scale present in the Ryugu whole-rock samples as well as to the characterization of the compositional variability of Ryugu in the insoluble organic matter (IOM) chemically extracted from the Ryugu samples. Methods . The AFM-IR maps of whole-rock particles and IOM residues from Ryugu samples were recorded with a lateral resolution of tens of nanometers. Spectra were recorded in the 1900–900 cm −1 spectral range by AFM-IR (Icon-IR) for all samples, and additional spectra were recorded from 2700 to 4000 cm −1 for one IOM sample by an optical photothermal IR (O-PTIR) technique using a mIRage® IR microscope. Results . Organic matter is present in two forms in the whole-rock samples: as a diffuse phase intermixed with the phyllosilicate matrix and as individual organic nanoparticles. We identify the Ryugu organic nanoparticles as nanoglobule-like inclusions texturally resembling nanoglobules present in primitive meteorites. Using AFM-IR, we record for the first time the infrared spectra of Ryugu organic nanoparticles that clearly show enhanced carbonyl (C=O) and CH contributions with respect to the diffuse organic matter in Ryugu whole-rock and IOM residue.

This paper is focused on the characterization of the thermal history of C-type asteroid Ryugu through the structure of the polyaromatic carbonaceous matter in the returned samples determined by Raman spectroscopy. Both intact particles and extracted Insoluble Organic Matter (IOM) from the two sampling sites on Ryugu have been characterized. The main conclusions are that (i) there is no structural difference of the polyaromatic component probed by Raman spectroscopy between the two sampling sites, (ii) in a manner similar to type 1 and 2 chondrites, the characterized Ryugu particles did not experience significant long-duration thermal metamorphism related to the radioactive decay of elements such as 26Al; (iii) some structural variability is nevertheless observed within our particle set. It can be interpreted as some particles having experienced some short-duration and weak heating (R3 in the scale defined by Quirico et al. 2018 and TII or lower according to the scale defined by Nakamura, 2005).

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Transmission electron microscopy analyses of Hayabusa2 samples show that Ryugu organic matter exhibits a range of morphologies, elemental compositions, and carbon functional chemistries consistent with those of carbonaceous chondrites that have experienced low-temperature aqueous alteration. Both nanoglobules and diffuse organic matter are abundant. Non-globular organic particles are also present, and including some that contain nanodiamond clusters. Diffuse organic matter is finely distributed in and around phyllosilicates, forms coatings on other minerals, and is also preserved in vesicles in secondary minerals such as carbonate and pyrrhotite. The average elemental compositions determined by energy-dispersive spectroscopy of extracted, demineralized insoluble organic matter samples A0107 and C0106 are C 100 N 3 O 9 S 1 and C 100 N 3 O 7 S 1 , respectively, with the difference in O/C slightly outside the difference in the standard error of the mean. The functional chemistry of the nanoglobules varies from mostly aromatic C=C to mixtures of aromatic C=C, ketone C=O, aliphatic (CH n ), and carboxyl (COOH) groups. Diffuse organic matter associated with phyllosilicates has variable aromatic C, ketone and carboxyl groups, and some localized aliphatics, but is dominated by molecular carbonate (CO 3 ) absorption, comparable to prior observations of clay-bound organic matter in CI meteorites.

Carbonaceous chondrites contain amino acids, with variable abundances and isotope compositions between and within carbonaceous chondrites. The parent body processes, and the presence of clay minerals may explain those differences. Here, we experimentally investigate the evolution of 6 amino acids (glycine, beta-alanine, alpha-alanine, 2-aminoisobutyric acid, gamma-aminobutyric acid, and isovaline) exposed to hydrothermal conditions in the presence or absence of silicates. We determined the chemical nature and isotopic composition of the organic compounds of the soluble and solid fractions of the residues using X-ray diffraction, spectroscopy, and mass-spectrometry methods. Glycine and alpha-alanine exhibit a rather high stability, which is consistent with the measured abundances of alpha-alanine and glycine in chondrites having experienced various degrees of aqueous alteration. In the meantime, the evolution of beta-alanine under hydrothermal conditions leads to the formation of a new compound, which likely results from the decarboxylation and deamination of beta-alanine followed by recombination. More than 95 % of gamma-ABA was transformed into 2-pyrrolidione though self-cyclization during the aqueous alteration. The solid residues of the experiments conducted in the presence of clay minerals contain organic material, with abundances varying depending on the amino acid used for the experiments (TOC isovaline > 2-aminoisobutyric acid > gamma-aminobutyric acid > glycine > alpha-alanine > beta-alanine). Clay minerals thus preferentially trap branched amino acids over chained amino acids, likely within their interlayer spaces as suggested by XRD data. The delta C-13 values of amino acids have not changed significantly during the experiments, even with the presence of silicates. Thus, the delta C-13 values of amino acids reported in CR and CM chondrites likely relate to synthetic conditions or the origin of their precursors (i.e. inherited from the pre-accretion processes).

We present here an investigation of Ryugu particles recovered by the Hayabusa2 space mission and their extracted carbonaceous acid residues using Raman spectroscopy. Raman parameters of Ryugu intact grains and their acid residues are characterized by broad D (defect induced) and G (graphite) band widths, indicating the presence of polyaromatic carbonaceous matter with low thermal maturity. Raman spectra of Ryugu particles and CI (type 1) chondrites exhibit stronger laser-induced fluorescence backgrounds compared to Type 2 and Type 3 carbonaceous chondrites. The high fluorescence signatures and wide bandwidths of the D and G bands of Ryugu intact grains are similar to the Raman spectra observed in CI chondrites, reflecting the low structural order of their aromatic carbonaceous matter, and strengthening the link between Ryugu particles and CI chondrites. The high fluorescence background intensity of the Ryugu particles is due to multiple causes, but it is likely that the relative abundance of geometry-bearing macromolecular organic matter in total organic carbon contents makes a large contribution to the fluorescence intensities. Locally observed high fluorescence in the acid-extracted residues of Ryugu is due to nitrogen-bearing outlier phase. The high fluorescence signature is one consequence of the low degree of thermal maturity of the organic matter and supports evidence that the Ryugu particles have escaped significant parent body thermal metamorphism.

The nature of the organic matter in interplanetary samples is central to elucidating the formation and early evolution of the Solar System. Although most meteorites derive from asteroids, micrometeorites mainly sample more remote objects. Ultra-carbonaceous Antarctic micrometeorites (UCAMMs), which have the highest carbon content among interplanetary samples, offer a unique window into cometary organics. Here we report a survey of the H, C and N isotopes in four UCAMMs, of which two are 15N-poor (delta 15N similar or equal to -120 parts per thousand), which suggests that their formation involved primordial N2 (delta 15N similar or equal to -380 parts per thousand). Such a composition could be the result of Galactic cosmic ray irradiation of N2 ices at the surface of cold small bodies in the outermost parts of the Solar System, possibly the Oort cloud. The two other UCAMMs exhibit higher delta 15N (75 parts per thousand and 282 parts per thousand), like those reported for carbonaceous chondrites and interplanetary dust particles. They may originate from parent bodies initially on lower heliocentric orbits in the Kuiper belt that have surfaces cold enough to retain N-bearing species, such as cyanides (delta 15N >= 200 parts per thousand), that are richer in 15N than primordial N2. According to their elemental and isotopic composition, UCAMMs constitute a unique probe into the coldest objects of the Solar System, namely those in the Kuiper Belt and the Oort cloud, which are largely out of reach of current space exploration. The hydrogen, carbon and nitrogen isotopic compositions of ultra-carbonaceous Antarctic micrometeorites reveal that they are possibly linked with N-bearing volatile species, including primordial N2, condensed on the coldest objects of the Solar System.