Carbonate Associated Sulphate (CAS) in travertines: A useful time capsule for inferring (paleo-) fluid-rock interaction and/or microbial fractionation?
Claes, H.; Paris, G.; Swennen, R. (2026). Carbonate Associated Sulphate (CAS) in travertines: A useful time capsule for inferring (paleo-) fluid-rock interaction and/or microbial fractionation? Chem. Geol. 716: 123497. https://dx.doi.org/10.1016/j.chemgeo.2026.123497
In: Chemical Geology. Elsevier: New York; London; Amsterdam. ISSN 0009-2541; e-ISSN 1872-6836, more
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| Author keywords |
cas;Carbonate associated sulphate;Sr-isotopes;Travertine;Continental carbonates;yellowstone-national-park;sulfur isotopic composition;mammoth hot-springs;field denizli basin;acque albule basin;geogenic co2 flux;western anatolia;geothermal-field;late pleistocene;stable-isotope |
| Authors | | Top |
- Claes, H., more
- Paris, G.
- Swennen, R., more
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| Abstract |
In light of continental sulphur cycling, we verified whether Carbonate Associated Sulphate (CAS) in travertines preserves pristine fluid signatures and can be used in geothermal exploration or as dating or stratigraphic tool, similarly to delta S-34 measured in marine carbonates. In other words, can CAS be applied to infer sulphur source in travertines, or is it affected by microbial mediation and/or diagenesis? Therefore, novel CAS analyses from travertines of famous deposits from Turkey (Ballik), Italy (Tivoli) and Hungary (Budakalasz and Sutto) were evaluated within their hydrogeological context. Results show that travertines dominantly inherited CAS and delta S-34 from their spring waters, controlled by paleo-geo-hydrology. The CAS signature consequently helps to pinpoint source rocks, providing complementary information to elemental compositions, O, C and Sr isotopes. Of potential interest for geothermal exploration, the studied cases reveal a "Travertine Play", i.e. different factors sharing similar exploration goals, of 1) elevated geothermal gradients, 2) active tectonics and presence of large-scale fault systems, 3) topography for gravity driven fluid flow and 4) (evaporite-bearing) carbonates in the subsur-face as "ingredients" for travertine formation. Sulphur in travertines, as reflected by delta S-34, originated respectively from the Late Triassic Kalebogazi Formation (Ballik area), the Late Triassic Burano Formation (Tivoli area) and the Triassic (-Permian) evaporites mixed with leaching from Oligocene sulphides (Budakalasz and Sutto areas). Microbial fractionation and diagenesis only play a minor role. The delta S-34 signature of travertines along their stratigraphy, consequently, provides an exquisite record of subsurface fluid-rock interaction and evolution through time. In this way, Pleistocene interplay between paleo-tectonics and -climate remains "set in travertine stone". |
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