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Physics of Isotopologues

Paleoclimate research: monitoring of a cave in the Odenwald region
Members of the research team explain to a SWR journalist what the goals of speleothem-based studies in this region are and why it is relevant today
Computational studies of calcium carbonate minerals
Molecular modelling of the complexation of alkali and alkaline earth metals to study the influence of the charge density in the ionic bond formation.
Optical clumped isotope thermometry of carbon dioxide
Simultaneous analysis of carbon dioxide isotopologues involved in the isotope exchange between the doubly substituted 13C16O18O molecule and 12C16O2.
Stable isotopes of fluid inclusions in speleothems
Laboratory setup for the measurement of stable isotopes in fluid inclusions of speleothems with CRDS technique.

The research of Dr. Kluge's group has its major focus on the investigation of multiply-substituted isotopologues, the understanding of physical processes that lead to isotope fractionation, and the application of new proxie techniques for paleoclimate reconstruction. Amongst others, carbonate clumped isotopes and noble gases in fluid inclusions are promising new techniques for the assessment of past climate variations that are applied in this research group.

The research group is part of the Heidelberg Graduate School of Fundamental Physics (HGSFP).



 - For the first time it is possible to measure, simultaneously and with extreme precision, four rare molecular variants of carbon dioxide (CO2) using a novel laser instrument. It is thus…




Clumped isotopes in paleoclimate research

Clumped Isotopes yield the unique oppurtunity for absolute temperature determination and are thus an ideal tool for paleoclimate reconstructions on carbonates. The research group focusses on speleothems consisting an abundant, well dateable and partially high-resolution archive. Clumped isotope signals in stalagmites are systematically influenced by disequilibrium effects during CO2 degassing from the precipitating solution. However, in combination with one additional parameter speleothems provide either absolute temperatures (given the fluid δ18O value can be indenpendently constrained, e.g. by fluid inclusions) or fluid δ18O values (if independent temperature estimates are used).


  • HCE boost fund , "Untersuchung und Interpretation von hochaufgelösten Isotopenprofilen im interdisziplinären Kontext". In collaboration between Environmental Physics and Geosciences the feasibility of high-resolution isotope ratio analyses with an ion microprobe on the µm scale is evaluated. It may allow for establishing annually resolved paleoclimate records that can be used as environmental baseline and can be used to put societal developments into the context of natural changes.
  • HEiKA project "Check Extrema", interdisciplinary research project on climatic extreme events investigated from Natural and Historical Sciences perspectives. Funded by the Heidelberg-Karlsruhe Research Partnership of Heidelberg University, and Karlsruhe Institute of Technology (KIT); Germany. Further information: HEiKA web site. Short video on the project outline, background details and first insights.
  • DFG project "Water isotopes in fluid inclusions of speleothems". Funded by the German Science Foundation DFG. Further information: DFG web site.

Advances in the absorption spectroscopic analysis of CO2 clumped isotopesIR_clumped_isotopes

A recent advance in mid-IR laser spectroscopic technologies provides us the necessary tools to access extremely low sub-permill variations of rare doubly-substituted CO2 isotopologues (e.g. 17O13C16O and 18O13C16O). The international collaboration of the research group with the laboratory for radiation and matter studies in astrophysics and atmospheres (LERMA-IPSL, CNRS / SU / PSL) in Paris has developed the first laser instrument to simultaneously measure the four most abundant molecules of CO2, containing carbon isotopes 12C or 13C and oxygen isotopes 16O or 18O at an uncertainty level of better than 0.05 per thousand. This type of analysis allows to determine the formation temperature of carbonates and has recently become a powerful tool in various scientific fields, such as paleoclimatology, geochemistry, and atmospheric sciences. So far, analyzes are done by highly specialized mass spectrometers, but the new method will allow faster and more direct analyses. This major instrumental and methodological advancement paves the way for a better and broader use of this technique.

Molecular modeling and simulation of carbonate minerals to determine physico-chemical processes and kinetic isotope effects

caco32_mos Carbonates minerals are extensively used for reconstruction of the Earth’s past climatic variations by determining ocean, lake, and soil paleotemperatures. The fundamental physical processes during the formation of such carbonate minerals are, in principle, accessible with theoretical models by, e.g., providing the isotopic ratios of natural tracers such as 13C and 18O. More specifically, molecular modeling and simulation, which is nowadays an essential enabling technology in almost all areas of contemporary science and engineering, is the key to our interdisciplinary research. Yet, the main challenge of interpreting such complex chemical systems by comparing ab-initio calculations with measurement results is in providing a suitable theoretical framework for our specific experimental set-up. We therefore are in the process to gain a profound molecular understanding of carbonate minerals in contact with liquids on the basis of electronic structure theory. In the end, we will use our detailed knowledge of the interface structure and its dynamic properties which allows to elucidate the physico-chemical processes, to predict (kinetic) isotope effects and to compare with experimental measurements.

Stable isotopes of fluid inclusions in speleothems

fluid_inclusionsFluid inclusions refer to small aliquots of water contained inside minerals. They are relicts of the original fluid environment and in suitable archives can provide insights into the solution δ18O and δD values and their evolution through time. Fluid Inclusions in speleothems archive the drip water from which they form and can therefore give important insights into paleo-hydrological conditions. We set up a precise method for water isotope analysis of fluid inclusions in speleothems using the CRDS technique (Weißbach et al., 2019). Cavity Ring-Down Spectroscopy is regularly used in many fields of environmental physics in isotope geochemistry, as it is a fast and cost effective. Currently we can routinely measure carbonate samples with a water yield of more than 0.2 μl with a precision of 0.5 ‰ in δ18O and 1.5 ‰ in δ2H. Absolute accuracy was assessed by interlaboratory calibration of selected samples, analysis of glass capillaries as well as modern speleothems samples with known drip water values.

Clumped isotope application to carbonates formed under reservoir conditions

co2_lineClumped Isotopes are a thermodynamic proxy that provides mineral formation temperatures independent from the knowledge of the fluid composition from which the carbonate precipitated. This technique was predominantly applied to carbonates that formed at Earth surface temperatures (0-40°C). Dr. Tobias Kluge investigated in the context of the Quatar Carbonates and Carbonate Storage Center (QCCSRC at Imperial College, London) constraints related to its application to reservoir conditions. Laboratory-based precipitation of carbonates at varying temperatures and different solution compositions provide the basis for broad-scale application to specific geoscience questions concerned with high temperature and high salinity environments.


Quantification of disequilbrium fractionation with clumped isotopes

labworkMany geological archives are influenced by disequilibrium effects. Carbonate clumped isotopes have proven to be very sensitive to disequilibrium in the CaCO3-H2O-CO2 system. As the disequilibrium in Δ47 and δ18O is linked, Δ47 measurements can under certain conditions help to quantify the disequilibrium (e.g., if the formation temperature is known). An exciting application is related to question what the true equilibrium fractionation factor between carbonate and water is. Using clumped isotope measurements we are able to determine if the respective carbonate sample precipitated at equilibrium (e.g., Kluge et al., 2014).



Current group members

Joint group picture of Werner Äschbach's and Tobias Kluge's groups: on the rightmost Therese Weißbach, in the center Erna (Therese's dog), second leftmost in the front Tobias Kluge, leftmost Halua Pinto de Magalhães

Name Position Room Tel.
Dr. Tobias Kluge group leader 229 / R330     6511
Dr. Halua Pinto de Magalhães postdoc 229 / R320 6314
Therese Weißbach PhD student 229 / R314 6528
Alina Straub BSc student 229/ R314 6528


New Publications

> complete list of publications

A. Baldermann, F. Mittermayr, S. M. Bernasconi, M. Dietzel, C. Grengg, D.
Hippler, T. Kluge, A. Leis, K. Lin, X. Wang, A. Zünterl & R. Boch, 2020.
Fracture dolomite as an archive of continental palaeo-environmental
conditions.Nature Comm. Earth Env., 1, 35.

C.Nehme, T.Kluge, S.Verheyden, F.Nader, I.Charalambidou, T .Weissbach,
S.Gucel, H.Cheng, R.L.Edwards, L.Satterfield, E.Eiche, Ph. Claeys,
2020.Speleothem record from Pentadactylos cave (Cyprus): new insights into
climatic variations during MIS 6 and MIS 5 in the Eastern Mediterranean.
Quat. Sci. Rev. 250.

Ufrecht, W., Kluge, T., 2020. Die Travertine von Böttingen und Laichingen (Miozän, mittlere Schwäbische Alb) – Archive für ein Paläo-Thermalwassersystem. Z. Dt. Ges. Geowiss., DOI:

Kluge, T., Münster, T. S., Frank, N., Eiche, E., Mertz-Kraus, R., Scholz, D., Finné, M., and Unkel, I.: A 4000-year long Late Holocene climate record from Hermes Cave (Peloponnese, Greece), Clim. Past Discuss., in review, 2020.

Dietzel, M., Purgstaller, B., Kluge, T., Leis, A., Mavromatis, V., 2020. Oxygen and clumped isotope fractionation during the formation of Mg calcite via an amorphous precursor, Geochim. Cosmochim. Ac., in press.

Prokhorov I., Kluge T., Janssen C., 2019. Laser absorption spectroscopy of rare and doubly substituted carbon dioxide isotopologues. Analytical Chemistry, 91, 24, 15491-15499

Quandt D., Micheuz P., Kurz W., Kluge T., Boch R., Hippler D., Krenn K., Hauzenberger C.A., 2019. Geochemistry of calcite veins hosted in the Troodos Pillow Lavas and their implications for the timing and physicochemical environment of fracturing, fluid circulation, and vein mineral growth, Geochem. Geophys. Geosys., in press.

Kalb, M., Kluge T., Eckhard H., Weise A., Prokhorov I., Kraml M., Eiche E., Neumann T., 2019. CO2,gas-H2Oliquid isotope exchange rates up to 150°C - experimental study and application to hydrothermal CO2. Geochmica et Cosmochimica Acta, 269, 167-183.

Weise, A., Kluge, T., 2019. Isotope exchange rates in dissolved inorganic carbon between 40°C and 90°C. Geochimica et Cosmochimica Acta, 268, 56-72.

Kluge, T., Schuh, M., 2019. Providing reliable data? Combining scientific and historical perspectives on flooding events in medieval and early modern Nuremberg (1400–1800). In: Making the Medieval Relevant, Eds. Jones, C., Kostick, C., Oschema, K.; Das Mittelalter, Beihefte 6, De Gruyter
in press

Prokhorov, I., Kluge, T., Janssen, C., 2019. Optical clumped isotope thermometry of carbon dioxide. Nature Scientific Reports.

Petersen, S. V., et al. (including Kluge T.), 2019. Effects of improved 17O correction on inter-laboratory agreement in clumped isotope calibrations, estimates of mineral-specific offsets, and temperature dependence of acid digestion fractionation. Geoch. Geophys. Geosys., in press. doi/10.1029/2018GC00812

Riechelmann, D.,Fohlmeister, J., Kluge, T., Jochum, K. P., Richter, D. K., Deininger, M., Friedrich, R., Frank, N., Scholz, D., 2019. Evaluating the potential of tree-ring methodology for cross-dating of three annually laminated stalagmites from Zoolithencave (SE Germany). Quaternary Geochronology, 52, 37-50 .

T. Kluge, Schuh, M., 2018. Detektivarbeit-Extremen Klimaereignissen auf der Spur, Ruperto Carola 12(2018), 97-105.

Boch, R., Wang, X., Kluge, T., Leis, A., Lin, K., Pluch, K., Mittermayer, F., Baldermann, A., Böttcher, M.E., Dietzel, M., 2018. Aragonite calcite veins of the ‘Erzberg’ iron ore deposit(Austria): Environmental implications from young fractures. Sedimentology.

Kluge, T., John, C.M., Boch,R., Kele,S., 2018. Assessment of factors controlling clumped isotopes and δ18O values of hydrothermal vent calcites. Geochemistry, Geophysics, Geosystems, 19.

Zhang, L., Wang, C., Wignall, P.B., T. Kluge, Wan, X, Wang, Q, Gao, Y., 2018. Deccan volcanism caused coupled pCO2 and terrestrial temperature rises, and pre-impact extinctions in northern China. Geology, 46, 271-274.

Boch, R., Szanyi, J., Leis, A., Mindszenty, A., Deak, J., Kluge, T., Hippler, D., Demeny, A., and Dietzel, M., 2016. Geothermal carbonate scaling: forensic studies applying high-resolution geochemical methods. Proceedings of the European Geothermal Congress.
ISBN: 978-2-9601946-0-9. S-GC.