Isotopic and structural signature of experimentally irradiated organic matter

Laurent, Boris; Roskosz, Mathieu; Rémusat, Laurent; Leroux, Hugues; Vezin, Hervé; Depecker, C.

doi:10.1016/j.gca.2014.07.023

Cited by 23 publications

(19 citation statements)

References 47 publications

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“…; Laurent et al. , ). Alternatively, they may have originated from different soluble precursors that led to different IOM signatures upon hydrothermal processing.…”

Section: Discussionmentioning

confidence: 97%

“…Scenarios involving the accretion of multiple populations of OPs with different formation environments and chemical origins have previously been proposed, based on isotopic mixing trends and isotopic hotspot heterogeneities (Al eon 2010; Remusat et al 2010). The respective precursors of each of the OP populations could be already insoluble at the time of accretion and thus record different thermal/irradiation histories from the nebula (Le Guillou et al 2013;Laurent et al 2014Laurent et al , 2014. Alternatively, they may have originated from different soluble precursors that led to different IOM signatures upon hydrothermal processing.…”

Section: Origins Of Om-chemical Heterogeneitymentioning

confidence: 99%

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Hydrothermal evolution of the morphology, molecular composition, and distribution of organic matter in CR (Renazzo‐type) chondrites

Changela

Guillou

Bernard

et al. 2018

Meteorit & Planetary Scien

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The morphology, molecular composition, and distribution of organic matter (OM) were investigated in a suite of CR chondrites to better constrain its hydrothermal evolution. Multiple focused ion beam sections were extracted from the matrices of seven CR chondrites. Scanning transmission X‐ray microscopy and transmission electron microscopy reveal OM ubiquitously distributed across the CR matrices. OM mainly occurs as either discrete submicron rounded or irregularly shaped vein‐like particles. Two spectral populations of organic particles were identified by carbon K‐edge X‐ray absorption near edge structure (XANES): the most abundant one, similar to insoluble organic matter (IOM) residues, contains aromatic, carbonyl, and carboxylic groups. The second population is more aromatic‐rich and lacks a distinctive carbonyl peak. An additional, ubiquitous organic component occurs associated with amorphous silicates and phyllosilicates. Less aromatic but aliphatic‐ and carboxylic‐rich, this diffuse OM is interpreted as the result of the redistribution of organic compounds by aqueous fluids. The most altered CR1 GRO 95577 contains a more mature OM and highly aliphatic‐ and carboxylic‐rich diffuse OM. This evolution, from the CR2s to the CR1, is comparable to that of terrestrial gas shale maturation involving cracking reactions, releasing bitumen‐like, aliphatic‐, and carboxylic‐rich compounds, and aromatic residues. Our observations support the accretion of soluble OM and its later polymerization to IOM, as well as the maturation of IOM and its partial oxidation, releasing mobile compounds. The differences in GRO 95577 are clearly attributable to the hydrothermal episode(s), but the relative role of water and temperature on the evolution of OM remains elusive.

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“…; Laurent et al. , ). Alternatively, they may have originated from different soluble precursors that led to different IOM signatures upon hydrothermal processing.…”

Section: Discussionmentioning

confidence: 97%

Section: Origins Of Om-chemical Heterogeneitymentioning

confidence: 99%

Hydrothermal evolution of the morphology, molecular composition, and distribution of organic matter in CR (Renazzo‐type) chondrites

Changela

Guillou

Bernard

et al. 2018

Meteorit & Planetary Scien

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“…Besides this main process of D enrichment, additional D/H enhancements, although less significant, may result from secondary processes; these processes are mainly induced by an exposition of extraterrestrial material to energetic particles (electrons and photons). Transmission electron microscopy coupled with NanoSIMS studies and X-ray irradiation followed by NanoSIMS studies have shown that irradiation processes may induce moderate D/H enhancements in carbonaceous matter after very high irradiation doses (de Gregorio et al 2010;Laurent et al 2014Laurent et al , 2015Gavilan et al 2017). These studies show that the D/H ratio increases with the deposited doses and then reaches a plateau at about 600-1000 permil at extremely high doses.…”

Section: H +mentioning

confidence: 94%

“…Moreover, in these two experiments the observed D enrichments are substantially smaller than those reported in meteorites or micrometeorites organics. The NanoSIMS measurements of irradiated samples by Laurent et al (2014) and Gavilan et al (2017) reported maximum D enrichment of about 600 to about 900 . The δD in carbonaceous chondrites range from 650 to more than 2500 (Robert et al 1981;Alexander et al 2010) and Remusat et al (2007) found values up to 5500 in the Orgueil meteorite.…”

Section: Electron and Photon Irradiationmentioning

confidence: 99%

Hydrogen isotopic anomalies in extraterrestrial organic matter: role of cosmic ray irradiation and implications for UCAMMs

Augé

Dartois

Duprat

et al. 2019

A&A

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Context. Micrometeorites represent, at timescales shorter than a few million years, the dominant source of extraterrestrial matter at the surface of the Earth. Analyses of ultracarbonaceous micrometeorites recovered from Antarctica, known as UCAMMs reveal an exceptionally N-rich organic matter associated with spatially extended high D enrichments. Experiments show that this specific organic matter might have been formed in the outer solar system by energetic irradiation of N-rich icy surfaces. Aims. We experimentally investigate the hydrogen isotopic fractionation resulting from irradiation of normal and D-rich N2-CH4 ices by high energy ions, simulating the exposition to Galactic cosmic rays of icy bodies surfaces orbiting at large heliocentric distances. Methods. Films of N2-CH4 ices and a N2-CH4/CD4/N2-CH4 “sandwich” ice were exposed to 129Xe13+ ion beams at 92 and 88 MeV. The chemical evolution of the samples was monitored using in situ Fourier transform infrared spectroscopy. After irradiation, targets were annealed to room temperature. The solid residues of the whole process left after ice sublimation were characterized in situ by infrared spectroscopy, and the hydrogen isotopic composition measured ex situ by imaging secondary ion mass spectrometry at the sub-micron scale (NanoSIMS). Results. Irradiation leads to the formation of new molecules and radicals. After annealing, the resulting poly-HCN-like macro-molecular residue exhibits an infrared spectrum close to that of UCAMMs. The residue resulting from irradiation of N2-CH4 ices does not exhibit a significant deuterium enrichment comparable to that found in extraterrestrial organic matter. The residue formed by irradiation of D-rich ices shows the formation of isotopic heterogeneities with localised hotspots and an extended contribution likely due to the diffusion of the radiolytic products from the D-rich layer. Conclusions. These results show that high-energy cosmic ray irradiation does not induce the large hydrogen isotopic fractionation observed at small spatial scale in interplanetary organics. By contrast, large D/H ratio heterogeneities at the sub-micron spatial scale in extraterrestrial organic matter can result from isotopically heterogeneous ices mixtures (i.e. condensed with different D/H ratios), which were transformed into refractory organic matter upon irradiation.

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“…Some of the sections examined by TEM were later subjected to isotopic imaging by NanoSIMS as described in the following section. Several studies have shown that high doses of electron beam exposure during TEM examination may induce dD enrichments in organic materials of 100s to 1000&, depending on deposited dose and the nature of the sample (De Gregorio et al 2010;Laurent et al 2014;Le Guillou et al 2013). To enable correlated TEM-H isotopic studies, we limited the TEM electron dose in sections to be measured for H isotopes.…”

Section: Transmission Electron Microscopymentioning

confidence: 99%

Pristine stratospheric collection of interplanetary dust on an oil‐free polyurethane foam substrate

Messenger

Nakamura‐Messenger

Keller

et al. 2015

Meteorit & Planetary Scien

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We performed chemical, mineralogical, and isotopic studies of the first interplanetary dust particles (IDPs) collected in the stratosphere without the use of silicone oil. The collection substrate, polyurethane foam, effectively traps impacting particles, but the lack of an embedding medium results in significant particle fragmentation. Two dust particles found on the collector exhibit the typical compositional and mineralogical properties of chondritic porous interplanetary dust particles (CP-IDPs). Hydrogen and nitrogen isotopic imaging revealed isotopic anomalies of typical magnitude and spatial variability observed in previous CP-IDP studies. Oxygen isotopic imaging shows that individual mineral grains and glass with embedded metal and sulfide (GEMS) grains are dominated by solar system materials. No systematic differences are observed in element abundance patterns of GEMS grains from the dry collection versus silicone oil-collected IDPs. This initial study establishes the validity of a new IDP collection substrate that avoids the use of silicone oil as a collection medium, removing the need for this problematic contaminant and the organic solvents necessary to remove it. Additional silicone oil-free collections of this type are needed to determine more accurate bulk element abundances of IDPs and to examine the indigenous soluble organic components of IDPs.

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Isotopic and structural signature of experimentally irradiated organic matter

Cited by 23 publications

References 47 publications

Hydrothermal evolution of the morphology, molecular composition, and distribution of organic matter in CR (Renazzo‐type) chondrites

Hydrothermal evolution of the morphology, molecular composition, and distribution of organic matter in CR (Renazzo‐type) chondrites

Hydrogen isotopic anomalies in extraterrestrial organic matter: role of cosmic ray irradiation and implications for UCAMMs

Pristine stratospheric collection of interplanetary dust on an oil‐free polyurethane foam substrate

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