Tag: ta2.17

22-EPN3-110: Clumped Isotope Thermometry of Travertines in the Tauern Window (European Alps) – Significance for Past Seismicity and Risk Assessment of the Brenner Base Tunnel

Visit by Diethard Sanders of the University of Innsbruck (Austria), to TA2 Facility 17 – Isotoptech Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 06-10 November 2023.

Report summary: In the European Eastern Alps, travertines precipitated from springs with superambient temperature are very rare. Travertines show fabrics distinct from ambient-temperature
spring limestones. We had identified three fossil travertine deposits in the Navis Valley, a valley between 1005 m a.s.l. (debouch) and a watershed at ~2300–2600 m a.s.l. The travertines are located at different altitudes (1816 m, 1706 m, 1228 m), and consist of stacked laminae 1.5–4 mm thick of radial-fibrous calcite. In active travertines, such fabrics characterise crystallisation at ~15-25°C. The Navis fossil travertines post-date the Last Glacial Maximum, as shown by four U/Th ages between 10.95 ± 0.08 to 9.94 ± 0.09 ka BP 1950 AD.

Clumped isotope thermometry (Δ47-thermometry) indicates that the travertine of each location precipitated at superambient temperatures well-above the mean annual air temperature in the recharge area. The travertine-depositing waters probably rose along a steep-dipping fault system in the rock substrate, whereby the activation of these faults may have been related to seismic activity. In the subsurface of the study area, faults associated with highly mineralised warm waters were encountered also in excavation of the Brenner Base Tunnel. Our results provide the first quantitative approach with respect to formation temperature and numerical age to the rare travertine deposits of the Eastern Alps, and may alert geologists to identify this specific type of deposit as a ‘warning hint’ for potential episodes of active faulting. This is relevant to seismic hazard assessment of buildings such as the Brenner Base Tunnel.

Read the full scientific report, with kind permission from Simone Silvestro.

20-EPN2-095: Carbon Isotopic Fractionation and Quantification in Perennial Cave Ice

Visit by Artur Ionescu of the Babes-Bolyai University (Romania), to TA2 Facility 17 – Isotoptech Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 27 November – 08 December 2023.

Report Summary: The aim of this project is to investigate the carbon isotopic variation in perennial cave ice in different phases, for the determination of fractionation processes and estimation of the carbon source (organic or inorganic). To do so, we aim of using two types of samples, the first from
extracted ice from perennial cave glacier and ice created in laboratory conditions. We measured δ¹³C in gases trapped as “bubbles” in the ice mainly CO₂, in dissolved carbon in the ice as HCO₃ and CO₃, and in the cryogenic cave carbonates.

Our hypothesis presumes that isotopic fractionation of carbon could shift an inorganic
signature towards a more organic one, thus making it difficult to assess the origin of carbon,
hence misinterpreting the origin.

In total 36 measurements have been performed on carbon-13. Our preliminary data on the
fractionation of carbon-13 show that during freezing the bubbles “concentrate” the light
isotopic ratios while the most enriched values were found in the cave carbonates. Thus
confirming our hypothesis. This is the first study that described isotopic values of carbon-13
in the different phases of the cave ice, however more laboratory experiments are needed to
better constrain the isotopic fractionation process.

22-EPN3-30: An Isotopic Inventory of Mars Analogue Environments

Visit by Michael Christopher Macey of the Open University (UK), to TA2 Facility 17 – Isotoptech Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 06-10 November 2023.

Report Summary: This study analysed the carbon, oxygen, sulfur, and nitrogen isotope profiles in physiochemically distinct analogue environments to establish how the viability of biologically induced isotope fractionation as a candidate biosignature. The analysis was performed on sediment samples collected from analogue environments proposed as appropriate analogues for Noachian-Hesperian waters requires environments (e.g., highly saline and sulfurous). Specifically, these environments were the Salt flats of Western Sahara, a hypersaline environment that contains sulfurous sediments below thick halite layers, the high-altitude lakes of the Argentinian Andes, which possess a chemistry like dilute, modelled martian water chemistries and are impacted by a low atmospheric pressure and large diurnal fluxes in temperature and UV, the salt pans of the Makadikadi basin, and hypersaline lakes in Spain.

The analysis identified varied isotopic signatures across locations suggestive of diverse environmental conditions in terms of their microbial community, geology and inputs to the environment. Key differences include: Positive ³⁴S ad low ¹³C values in the Botswanan sediments, aligning with the detection of oxic conditions, while negative values in Argentinian and Saharan samples indicate a contribution of dissimilatory sulfur metabolisms. Variation in ¹⁵N values between environments highlight previously detected variation in the presence and abundance of nitrogen-dependent metabolisms. The ¹⁸O values also strongly support the input of glacial water into the Argentinian lakes. The synthesis of this isotopic analysis with geochemical and microbiological datasets from these Mars analogue environments stands to provide crucial insight into their role as potential biosignatures.

22-EPN3-128: Northwestern Amazon regional convection and its role in the control of extreme events and the isotopic signal in Quito, Ecuador.

Visit by Maria Sheila Fabiola Serrano Vincenti, Universidad Politécnica Salesiana (Ecuador), to TA2 Facility 17 – Isotoptech Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 22-26 May 2023.

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.

Read the full scientific report with kind permission by Sheila Serrano-Vincenti.

22-EPN3-032: Soil carbonate clumped isotope-based reconstruction of temperature evolution over the Mid-Pleistocene Transition and the Late Pleistocene

Visit by Ramona Schneider, Uppsala University (Sweden), to TA2 Facility 17 – Isotoptech Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 20 February – 03 March 2023.

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.

20-EPN-030: Identification of Metabolic Activity in Millennial Old Cave Ice

Visit by Aurel Persoiu of the Emil Racovita Institute of Speleology (Romania) to TA2 Facility 17 – Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 15-29 November 2023

Report Summary: Scarisoara Ice Cave (Apuseni Mts., Romania) hosts a more than 10,000 years old ice block. Previous studies have shown that the ice hosts a varied microbial and fungal ecosystem, with more than 50% of taxa being culturable (i.e., alive). The main question of this project was whether the oxygen gas was consumed in the ice by the metabolic activity of microbes (and/or fungi), so we aimed to determine the Ar/O2 ratio in the gas extracted from the ice.

Two duplicate ice samples were analysed. One of them was deposited during the warm Medieval Warm Period, roughly between AD 800 and 1200 (labelled MWP), while the other accumulated during the subsequent cold Little Ice Age, between AD 1200 and 1850 (labelled as LIA). The Ar/Kr and Ar/Xe ratios indicate the ice was deposited as ponding water was slowly freezing. No entrapped air bubbles were present in the ice. This data fits to modern observations, since the top of the ice are covered by liquid water during summertime, which subsequently freezes in winter. As Ar/O2 ratios show oxygen depletion cannot be detected in the ice. The δ¹³C of CO₂ in the air equilibrated water samples compares to dissolved atmospheric CO₂, while δ¹³C in the ice samples represents depleted CO₂ from the root zone of vegetation growing above the cave. δ¹⁸O of O₂ is similar to that of atmospheric oxygen. As a conclusion, we cannot confirm that oxygen depletion occurs on the ice due to microbial consumption; however, the results are not conclusive and a subsequent sampling campaign to collect more samples is scheduled for 18-25 February 2023.