In this TA visit, the team investigated the abundance and isotopic composition of noble gases (He – Xe) in CM chondrites that record both aqueous and thermal metamorphism. These unusual meteorites are likely good analogues for the types of material found on the surfaces of primitive C-type asteroids; however, the timing and mechanism of the metamorphism remains unknown.
The team measured He – Xe in five CM chondrites that experienced peak metamorphic temperatures of <300°C to >750°C using stepped-heating and the “ALBATROS” mass spectrometer at the ETH Zürich Geo- and Cosmochemistry Noble Gas Laboratory. Preliminary results show that the concentrations of 4He and 22Ne are depleted in the lowest temperature steps (300 and 450°C) for all samples, consistent with degassing during (a) metamorphic event(s). Peaks in the concentration of both light and heavy noble gases in the 660°C and 800°C steps agree with previous estimates of metamorphic temperatures based on mineralogy and H2O loss. Isotopic compositions are mainly a mixture of primordial (so-called Q/HL) and cosmogenic components. In addition, EET 96029 and WIS 91600 contain a trapped solar wind component, suggesting that these meteorites may have been heated by impacts during residence in the asteroid regolith. Comparison of the data to unheated CM chondrites will be used to further constrain the thermal history of C-type asteroids in the early Solar System.
Report Summary: In this project different bright areas of Haulani crater (i.e. Southern floor and Central Crater Peak, named ROI3 and ROI1) on Ceres have been studied by producing different analogue mixtures starting from previous results and comparing them with Dawn VIR data. The end-members have been identified based on previous studies (Tosi et al. 2018, Dirri et al. 2022) and the analogue mixtures have been produced with grain size 50-100 µm. The two initial mixtures, i.e. SF1 and CCP_#1 have been acquired in the VIS-NIR spectral range (0.4-4.5 µm) at T environment. The Band Center, Band Depth and FWHM of absorption bands at 2.7, 3.1, 3.4 µm, spectral slope (1.2-1.9 µm range) and reflectance level at 2.1 µm of the produced SFs and CCPs mixtures have been analysed and then compared with VIR data.
The best analogues are the SF_#5 and CCP_#6 mixtures and their spectra have been acquired at low temperatures, i.e. from 190K to 230K, similar to Haulani base temperature by using Cold Spectroscopy Facility (CSS) (IPAG, France). These mixtures exhibit values for the 2.7BD (Antigorite, Illite), 3.1BD (NH4-Montmorillonite) and 3.4 BD (NaCO3) similar to Haulani ROI3 and ROI1. In particular, different dark components have been used (i.e. magnetite plus carbon black) with the aims of better reproducing the Haulani spectral slope and reflectance level. Different carbonates mix involving trona, dolomite, hydrous and anhydrous natrite have been studied to assess their contribution to 2.7 µm spectral band and the three minima at 3.33, 3.42, 3.52 µm of Haulani ROI3.
Report Summary: The main goal of the visit was to conduct in-situ U-Pb geochronological study of phosphate minerals in the Antonin L chondrite. Fall of the Antonin, on 15th July 2021, was recorded by European Fireball Network, and this recording led to reconstruction of the pre-atmospheric orbit of meteoroid. The orbital parameters of the Antonin differ from reconstructed orbits of other L chondrites, but suggest it was sourced from the inner asteroid belt. To track the orbit to the parent body, it is important to understand dynamic collisions experienced, which are recorded in minerals of the meteorite. U-Pb dating allows to decipher details on events that led to resetting of phosphates.
During the visit to KBSI facility, we collected SHRIMP (Sensitive High-Resolution Ion MicroProbe) analyses within multiple apatite and merrillite grains. Initial U-Pb results show minor discordance of ages of phosphates, indicating a mild collision after the crystallization of the minerals. The timing of reset event cannot be inferred with high precision, but it likely occurred between 500–100 Ma.
Additionally, formation of phosphates can be well constrained from collected data at ca. 4450 Ma. This age implies that phosphates formed/recrystallized in response to a collision as impacts were the only source of heat after cessation of accretional activity. Altogether, the results suggest two collisions in the evolution of parent body and will be combined with further data to pinpoint key events in dynamical evolution of parent body of L chondrites.
Report Summary: A total of 184 U-Pb-ages of zircon from eclogites from Sulu-Dabie UHP metamorphic belt (China), the D’Entrecasteaux Islands (Papua New Guinea) and the Western Gneiss Region (Norway) were successfully determined using the SHRIMP IIe/mc of the Korean Basic Science Institute.
Using the concordia method, we could identify a concordant age of the peak metamorphism of eclogite from Sulu-Dabie of ca. 240 Ma. In addition, a discordant age of around 720 Ma could be identified, which may reflect the age of inherited, magmatic zircon cores. The zircon from the D’Entrecasteaux Islands revealed ages below 8 Ma, which is younger than ages previously measured on the same sample in a previous study. This makes this sample one of the youngest eclogites ever discovered on Earth’s surface. Zircons from the Western Gneiss Region reveal ages of three distinct events. With 1.5 Ga, the oldest age determined probably reflects the Precambrian formation of the UHP region, while ages of around ca.
900 Ma correspond with the Sveconorwegian orogeny. The youngest age found in Norway reflects the Scandian orogeny at an age of ca. 415 Ma. The age information obtained will help us to develop improved evolutionary models for the formation of UHP rocks by combining these ages with trace element data.
Report Summary: This study investigates the Neoarchaean to Paleoproterozoic Transvaal Supergroup sedimentary sequence in Botswana that formed in the centre of the Kaapvaal Craton during the early oxygenation of the atmosphere. We used U-Pb dating on magmatic and sedimentary zircons from throughout the sedimentary sequence to determine the tectono-magmatic evolution of the hinterland basement. This approach constrains regional crustal growth, uplift and erosion events and establishes if additional cratons were in the hinterland, e.g. Pilbara. Knowledge of zircon provenance will allow critical comparison to known tectonic scenarios, e.g. Alpine style molasse basin and any potential change in Neoarchaean tectonics by considering erosion and crustal growth-reworking. The geochronology results help evaluate spatial and temporal variations in depositional environments associated with oxygenation of the atmosphere. Results indicate that the age of the basement, Gaborone Granite and the Kanye volcanic are indistinguishable (2768.9 ± 6.0 Ma). Sediments deposited from 2.642 Ga to 2.550 Ga are also dominated (> 90%) by zircons of ~2.77 Ga. This implies that there was a major crustal growth event in the Kanye region at 2.77 Ga that included minimal crustal reworking. Erosion products to the Kanye Basin are derived from this juvenile crust throughout the Archaean and Proterozoic until > 2.0 Ga. Only then are older and younger basement rocks recorded in the sedimentary sequence. This region of the planet yields no evidence of a major tectono-magmatic event associated with the oxygenation of the atmosphere.
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: Fifteen high-pressure experiments on the PISL end-loaded piston cylinder press were performed at 1 GPa and 1873 K to systematically investigate the effects of Cu and Ni on metal- and sulfide-silicate partitioning of highly siderophile elements (HSE) Pd, Ru, Pt and Ir. Run times at peak conditions varied around 60-90 minutes. The starting compositions consisted of silicate, sulfide and metal powders with added metallic Si. The experimental run products consist of well-segregated metallic and sulfide blobs in a silicate glass. The addition of metallic Si and the initial reduction of the experiments result in the suppression of nugget formation. The glass does contain minute specks typical of S- saturated silicate melts – subsequent LA-ICP-MS measurements of the run products show that these specks do not contain HSE, as initially hypothesized. Electron microprobe and LA-ICP-MS analyses further show that the experimental run products are homogeneous and no compositional zoning was observed. Initial results show that the addition of Cu and Ni to the sulfide liquid decreases the O content of that sulfide liquid at a given FeO value of the silicate melt. This will most certainly affect the partitioning of the elements of interest – preliminary results for Pt confirm this by its variation by three orders of magnitude at a given FeO content. Preliminary results also show that Pd, Ru, Pt, Ir are all preferentially partitioned into the metallic liquid instead of the sulfide melt, confirming their preference for S-poor alloys relative to S-rich liquids.
Report Summary: Twelve high-pressure experiments on a piston cylinder press were performed at 1 GPa and 1673-1873 K to systematically investigate the sulfide-silicate partitioning of chalcophile elements as a function of (non-FeO) silicate melt compositional terms. Run times at peak conditions varied around 70 to 220 minutes. The starting compositions consisted of silicate and sulfide powders. The experimental run products consist of well-segregated sulfide blebs in a silicate glass. The glass contains minute sulfur blebs but subsequent LA-ICP-MS measurements showed that these blebs do not contain the elements of interest and are composed of Fe-S-O. Electron microprobe and LA-ICP-MS analyses further showed that the experimental run products are homogeneous and no compositional zoning was observed.
Initial results show that variations in silicate melt composition affect the partitioning of chalcophile elements in a non-ideal way – i.e. FeO activity varies significantly across different melt compositions, thereby affecting the geochemical behavior of the elements of interest. Therefore, it can be expected that in an arc-type differentiation suite the sulfide-silicate partitioning behavior may vary significantly, purely due to variations in FeO activity due to variable silicate melt compositions.
Analyses of Martian meteorites and their components predicts the existence of three main geochemical reservoirs on Mars, namely an enriched crust, a complementary depleted lithospheric mantle, and, lastly, a primitive asthenospheric mantle. Investigating the oxygen isotope composition of these reservoirs is critical for a full understanding of the accretion history of Mars. The Δ17 O composition of ~0.3‰, defined by the SNCs is believed to reflect the primary planetary composition of the martian mantle (1). However, analyses of ancient (>4.5 Ga) individual zircons and minerals from the NWA 7533 regolith breccia, record Δ17 O values that are characterized by a much heavier Δ17 O composition and thus different from the SNCs (2,3). A population of young zircons (<1.5 Ga), also from NWA 7533, are derived from a primitive reservoir located in the deep martian interior, as they are characterized by chondritic-like initial Hf isotope composition (4).
The oxygen isotope composition of a single grain from this population, indicate that this reservoir may be characterised by a different Δ17 O than the SNCs. If correct, the SNCs might not be representative of the bulk martian composition, but plausibly reflecting interaction with a heavy Δ17 O surface reservoir. Therefore, a main objective behind this study was to obtain high-precision oxygen isotope composition of 10 SNC meteorites to potentially detect Δ17 O heterogeneity. However, initial results show no isotopic variability, thus suggesting that the SNC source reservoir has not experienced interaction with surface reservoir, or that any heterogeneity has been erased.
One of the major unresolved questions in the field of cosmochemistry is to understand the source(s) and timing of volatile delivery in the inner Solar System. The goal of this project was to examine primitive achondrites which volatile inventory has not yet been investigated, in order to determine what portion of these volatiles was incorporated in the early stages of the Solar System history, relative to late-veneer delivery. In this regard, primitive achondrite acapulcoites and lodranites were selected as they sample a common parent body, hence allowing to also investigate the effect of various degrees of planetary differentiation on volatile abundances and isotopic compositions.
Using the NanoSIMS 50L at the Open University, we analysed chlorine and water content, as well as their associated isotopic composition in phosphates from three acapulcoites and two lodranites. Our results suggest that the acapulcoite-lodranite parent body incorporated a similar source of volatiles than ordinary chondrites, which chemical composition is similar to the chondritic precursor of acapulcoites and lodranites, arguing for a common reservoir of both Cl and H in the inner Solar System.
20-EPN2-052: Water in silica-bearing iron meteorites – implications for early Solar System dichotomy
Visit by Ana Černok, Freie Universität Berlin (Germany)/University of Trieste (Italy) to TA2 Facility 21 – OU NanoSIMS 50L (UK). Dates of visit: 14-21 November 2022 and virtual visit from 28 November – 20 December 2022
Understanding the volatile inventory of the earliest Solar System is inseparable from understanding which sources contributed to the volatiles of the oldest and relatively dry non-carbonaceous (NC) objects formed in the inner Solar System, and if they were different from wet carbonaceous (CC) materials, formed in the outer Solar System.
Two questions remain largely unanswered in this respect: (i) What are the abundances and isotopic composition of volatiles in the oldest NC objects and (ii) What were their sources? These questions can be answered by investigating some of the oldest objects in the Solar System, namely, the NC iron meteorites.
This Europlanet visit to the NanoSIMS facility was focused on trying to determine the content and isotopic composition of H or H2O inside minerals within iron meteorites. The iron meteorites are some of the oldest formed materials in the Solar System and hold key evidence if there has been any water available when they formed, and if there was: where did this water originate from?
Here we focused on understanding water abundance and its isotopic composition in some of the oldest NC silica bearing iron meteorites (IVA type): Muonionalusta, Gibeon and Steinbach. Other investigated irons did not contain any silica. The lowest water content was measured in Gibeon (< 10 ppm) and Muonionlusta (15–20 ppm), while minerals in Steinbach contained significantly more water (40–120 ppm). The δD values for Gibeon show a large range and greater uncertainties, due to low measured water contents. The δD values in Muonionalusta and Steinbach cluster between ~0–300 ‰. In fact, silica phases in both minerals cluster between ~0–200 ‰, while low-water cpx in Steinbach shows the highest δD values (200–300 ‰). The difference in δD values between mineral phases in Steinbach likely reflects the difference in their crystallisation history, where opx may have lost H resulting in increased D/H ratio (higher δD) due to degassing. Overall, the source of water in these NC irons is very similar to that of the Earth and the chondrites, while low-D reservoirs have not been detected.
Report Summary: A vast range of different gully morphologies occurs on Mars: from the classical gullies, which resemble gullies on Earth, to linear gullies that do not have an Earth counterpart and are found on Martian dunes. Previous experiments have shown that the sublimation of CO2 ice can fluidise and transport sediment in the classical gullies on Mars. However, the linear gullies are hypothesised to form by a different, although related CO2-driven mechanism. For linear dune gullies, it is hypothesised that they form by a block of CO2-ice sliding down the dune. This process has, however, never been observed in real life.
With our visit to the Mars chamber at the Open University, we aimed at deciphering the triggering and forming mechanisms of linear dune gullies on Mars. We identified the possible triggering mechanisms based on hypotheses presented in the literature. The identified mechanisms are; 1) the breaking off and sliding down of CO2-ice blocks, and 2) wind-blown sand being deposited on CO2 frost. We systematically tested these mechanisms in the Mars Chamber at the Open University by means of experiments. For all identified triggering mechanisms a parameter space was used to test the influence of e.g. CO2-ice block size, surface slope and grain size.
With our experiments, we show that CO2-ice blocks slide downslope and create small narrow gullies when dumped on top of fluvial sand, with a large grain-size distribution. However, when dumped on a finer aeolian sand under Martian atmosphere, they do not slide downslope but they dig themselves into the sand, slowly digging a gully downslope by vigorous sublimation and sediment mobilisation. We also show that when a small amount of warm sand is dumped on top of a CO2-frosted the sand is mobilised by CO2 sublimation, but that this process does not create the typical linear gullies we see on Mars.
Report Summary: Our experimental campaign aimed to understand sediment transport driven by CO2 ice sublimation condensed inside a porous regolith. To quantify the erosion of sediment associated with the sublimation of CO2 frost in the subsurface of a ~30° slope, we tested various compositions (MGS-1, sand, sand-dust mixtures). While some sediment showed little to no activity over several attempts (sand), others showed significant slope activity (sand + >=10% MGS clay).
Report Summary: This project was designed to extend previous research of mud behaviour in the low-pressure conditions – with implications for potential sedimentary volcanism on Mars. The main objective was to test the effect of ice (or combined ice-sand) substrate to flow abilities and finite morphology of mudflows. As secondary objectives, testing of various inclinations of the surface, investigation of potential thermal erosion and extended study of another type of surfaces were implemented.
In the first part of the project, nine successful experiments, with pure and variously inclined (2-10°) ice surface, confirmed a different style of mud propagation than in case of the frozen sandy surface. The major observations are: 1) dominant and prevailing boiling of mud mixture during the propagation over deeply frozen ice surface (confirms significance of latent heat related to melting/recrystallization), 2) explosive potential of ice when in contact with the boiling mud (fracturing, contraction-dilatation). The effect of slope in tested range has no significant impact on these observations.
The second type of experiments tested combined ice-sand upper lid. Here, transition between boiling and freezing of mudflows was faster and finite morphology was more similar to lava-like flows which were described by Brož et al. (2020a).
In both cases, the thermal erosion was not confirmed. Moreover, during sectioning and investigation of the finite mudflow shapes and their base, the developed bumps, irregularities or even increased porosity of ice lid were discovered. This might refer to more complex thermal exchange between ice and mud with a sequential melting and re-freezing.
Report Summary: Current hostile conditions on the surface of Mars entail that, if any life form has ever existed on the planet, it may have adopted survival strategies like those evolved by terrestrial microorganisms inhabiting extreme environments e.g. Antarctica. There, one of the most common strategies observed is the cryptoendolithic microbial growth where free-living black fungi living along with algae and lichens within rocky interstices serve as a shield from excessive harmful solar radiation, and their extremotolerance can be mainly due to the presence of thick, highly melanised cell walls.
The ability of these cryptoendolytic microorganisms to thrive under extreme conditions raises the question of whether they cope with them by also regulating their metabolic expression in addition to melanin production, and whether a hypothetical microbial life on Mars could ever have arisen with similar adaptive strategies. In this optic, this study aimed to examin the metabolic regulation of melanised, cryptoendolithic microorganisms in martian scenario. To achieve this goal, colonies of the cryptoendolithic black fungus Cryomyces antarcticus previously exposed to simulated martian conditions such as perchlorates, sulfatic regolith soil and γ radiation, were then analysed with NMR spectrometry at the Center for Microbial Life Detection of the Medical University of Graz. Sample preparation and analysis were carried out in the Facility using standard protocols. Although only preliminary data are available at the time of report writing, significant differences in fungal metabolic expression were observed between the different simulated martian conditions tested.
Report Summary: This project focused on the analysis of three samples from the Black cave (Grotta Nera) located in Majella Park (Abruzzi region, Italy). This cave presents outstanding calcitic moonmilk structures that are unique in the World in terms of both abundance and dimension.
Metagenomic and metabolomic analyses of three samples (A1, apical; A2, lateral; A3, core) collected from one of the moonmilk speleothem from Grotta Nera, were performed. The DNA was extracted using the DNA powersoil kit (Qiagen) modified to include a bead-beating step with MagNA lyser (Roche) for the initial sample treatment. MG-RAST was used to analyse the metagenomic data considering both the taxonomy composition and the functional categories (KO categories). The taxonomy composition of the metagenomic sequences indicated that the dominant phyla were Proteobacteria, Actinobacteria, Firmicutes, Planctomycetes, Acidobacteria, and Verrucomicrobia. Actinobacteria were more abundant in the A1 and A2 as compared to the A3 sample, while in A3 Proteobacteria (in particular, Betaproteobacteria) was enriched as compared to other two samples. The metabolomic analysis was carried out using NMR, extracting the metabolites from 100 mg of each sample (in triplicate). The results indicated that in A2 and A3 samples were enriched by specific metabolites (glycerol in A3 and alanine, acetate, ethanolamine and 3-hydroxybutirate are enriched in A2) suggesting distinct metabolic activities in the microbial communities of these two samples.
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.
Example of a carbonate sample and the tools used for drilling. Credit: R Schneider
Europlanet 2024 RI has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 871149.
Europlanet AISBL (Association Internationale Sans But Lucratif - 0800.634.634) is hosted by the Department of Planetary Atmospheres of the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Avenue Circulaire 3, B-1180 Brussels, Belgium.