Report Summary: Zebra dolomites are marked by an alternation of millimeter thick dark colored, as recrystallised interpreted bands and white cement bands. Disruption of the banding is manifested by displacements that gradually increases and subsequently deceases before disappearing. This disruption also occurs at intracrystalline scale with crystal rehealing features as observable under cathodoluminescence. This disruption of the zebra dolomites is explained by dolomitization in relation to overpressured fluid flow.
In the framework of the Europlanet project zebra dolomite samples from 3 deep Belgian boreholes (Soumagne, Soiron and Bolland) were selected for clumped isotope analysis. The aim was to sample and analyse the dark fine crystalline and white coarse dolomite cements separately to infer the original (re)crystallization temperature. The following research questions were raised: i) is there a systematic difference in deduced temperature between the dark and white dolomite bands. If so then this could help to better constrain the recrystallisation and cementation. This would allow to assess the potential resetting of the original clumped isotope signature of the dark bands due to recrystallisation; ii) if the cement phases display uniform temperatures then this temperature can be compared with the minimum crystallization temperature deduced from primary fluid inclusion microthermometry . The discrepancy between both temperatures, which links to the pressure correction, normally allows to quantify the overpressure of the system; iii) based on deduced crystallization temperature and δ18OPDB, the δ18OSMOW of the fluid can be assessed, allowing to constrain the origin of the dolomitizing fluids, certainly when combined with Sr isotope analysis.
Report Summary: The goal of the 2023 visit to the TA Facility was to measure rainwater δ2H and δ18O values sampled at daily and monthly resolution from October 2022 to May 2023 in three different monitoring sites at North, South and Valley sites in Quito-Ecuador. Due to the complex orography, the sites experience varying intensities of rainfall and hailstorms. These measurements are part of a project aiming to understand the dynamical processes that contribute to the observed heavy and extreme precipitation events in the Tropical Andes, specifically in Quito.
Understanding these isotopic data will help the interpretation of the variations in δ2H and δ18O during intense rainfall events and subsequent fractionation due to local and upstream convection, orographic lift and moisture recycling. In addition to the measured isotopic signals, rainfall amount, pH, conductivity, and Total Dissolved Solids (TDS) data will be statistically analysed from the sites. Similarly, instrumental daily precipitation and cloud coverage information from instrumental and satellite data will be examined for convective rainfall (thunderstorms) and moisture provenance characterisation.
Report Summary: At the AQUILA chamber in the ECRIS Laboratory at the Atomki Institute for Nuclear Research the effects of H+, O2+, and S5+ irradiation of water ice, plus Formamide, as a potential prebiotic Europa ocean analogue were explored. Three sodium chloride windows, covered with a 1:1 ice mixture of water and Formamide, were irradiated with ion beams. The windows were cooled down to 90K in vacuum, and a 200-250 nm thick ice layer was deposited at them. In the first experiment, the sample was irradiated using a 15keV H+ ion beam in 12 steps, up to a total fluence of 1.1x 1015 ion/cm2. After each irradiation steps an infra-red (IR) spectrum was taken to observe the irradiation products. After completing, the sample was warmed up to 300K in 30K increments, taking an IR spectrum at each interval. During both irradiation and heating, the sputtered molecules were monitored by QMS. Finally, after a full warming up of the cold parts we opened the chamber, removed the sample (for post-TA residue analysis using LCMS/MS), replaced the NaCl window, and pumped the chamber. This protocol was repeated (with different irradiation fluences) for 30keV O2+ and 60keV S5+ ion beams. All the sample windows have been taken for residue analysis. From initial analysis of the spectra it seems that the Formamide was broken, and formed products such as CO, CO2, OCN–, and CN–. Further investigation is required to confirm these results and to determine what other products were created during the irradiation.
Report Summary: This project is devoted to investigate geo- and biosignatures that can be preserved in mineral assemblages formed in extreme aqueous terrestrial environments. Environments such as subaerial hot springs that could had existed on early Mars, and cold-seep marine environments that can develop in icy-moon oceans are particularly interesting for astrobiology. In order to achieve this goal, we use information obtained by Raman spectroscopy and SEM/EDX microscopy.
Raman spectroscopy is a recently incorporated analytical technique in the payload of several space missions: SHERLOC@Perseverance, Supercam@Perseverance, RLS@ExoMars and RAX@MMX. It is based on the scattering effect generated by the interaction of photons with the electron density of the chemical bond of a molecule. The position and width of the Raman bands give information on the structure, chemical and isotopic composition and crystallinity of mineral. Studying changes in Raman frequencies allows to evaluate the biological or inorganic origin of the sample. This methodology is relevant for the in-situ identification of geo- and bio-signatures in soil/rock samples collected during space missions.
Several bio-mediated minerals sampled from several hydrothermal and cold-seep areas were characterised by micro-Raman spectroscopy coupled with scanning electron microscopy (SEM/EDX). Obtained Raman spectrum was correlated with its texture in order to identify patterns that would allow us to assess the biological or inorganic origin. We observed Raman band shifting and width changes. These results should be complemented by further experimental work to determine the involvement of bio-mediation processes.
The main goals of the 2023 visit were to study the electron impact emission cross sections, spectral features, and dissociation thresholds of CS2 gas. The products of CS2 – atomic sulfur and its ions, CS, excited CS2, and CS2+ – make CS2 a rich target of inquiry. Further, the products CS and atomic S are routinely observed in near-nucleus observations of comets (see e.g. discussion in Noonan et al. 2023). Measurements of sulfur abundances in comets show discrepancies between remote and in-situ observations, and improved electron-impact data for CS2 may help resolve this discrepancy. The present experiments are part of a long-term campaign to understand diagnostic electron-impact driven emission and ionization of diatomic/polyatomic molecules in cometary atmospheres. We expect these data will provide valuable insights in one of our ongoing projects to investigate sulfur abundances through analyses of 100+ archived comet observations. In the first week of our visit to the EIF lab, we measured the electron-impact spectrum of CS2 gas at various electron energies between 0 – 100 eV, with energies chosen based on known thresholds for CS, CS2+, and atomic fragment production. During this time, we also began developing an emission model for CS in order to simplify the future analyses of these data. In the second week of the visit, higher-resolution spectra and several cross sections were measured in order to begin comparisons to existing literature. We also identified, for the first time, the emissions of atomic fragments (S I, S II) in the near-infrared red-ward of 600 nm.
Report Summary: This study describes the use of carbonate clumped isotope thermometry as a method of reconstructing paleotemperatures from soil carbonate concretions. The method is based on the tendency of rare, heavy isotopes of carbon and oxygen to clump together in a single CO2 molecule, which is temperature-dependent.
The analysis was performed on 12 samples that forme under a Mediterranean climate regime in Tajikistan to investigate the suitability of these samples for clumped isotope thermometry. The reconstructed temperatures of the Tajik Holocene soil carbonate nodules from three different locations show promising results, indicating that the Δ47 clumped isotope method provides reliable results for this sample type.
The obtained temperature values showed that these carbonates record temperatures that are biased towards summer temperatures. This is likely due to their formation during the summer when temperatures are highest and precipitation ceases after the maximum annual rainfall period. Even the results from older soil carbonates that formed under glacial and interglacial stages dating several glacial cycles back (MIS 11-12 and MIS 21) are well constrained, but a clear difference in formation temperature between glacial and interglacial stages could not be observed. This result can possibly be explained by formation processes of the soil carbonates, but more chronological and temperature data is required to further test this assumption and to investigate which exact period of the geological history is represented by the reconstructed temperatures. Despite these uncertainties, these initial results are very promising and highlight the potential of this method for paleotemperature reconstruction in Central Asia.