Demény Attila, Rinyu László, Dublyansky Yuri, Bajnóczi Bernadett
Institute for Geological and Geochemical Research, HUN-REN Research Centre for Astronomy and Earth Sciences, Budaörsi Út 45, Budapest, 1112, Hungary.
CSFK, MTA Centre of Excellence, Konkoly Thege Miklós Út 15-17, Budapest, 1121, Hungary.
Sci Rep. 2025 Mar 14;15(1):8800. doi: 10.1038/s41598-025-92824-w.
Knowledge of the formation temperatures of geological deposits is essential for investigating their genesis. Oxygen isotope thermometry (OIT), using the temperature dependence of oxygen isotope fractionation between host carbonate mineral and mineral-forming water trapped in fluid inclusions, and clumped isotope thermometry, based on the degree of C and O clumping, are receiving increasing interest. However, only a few studies have applied combinations of these methods, and their databases are limited. In this study, we compare OIT and clumped isotope temperatures obtained for 18 samples from Mesozoic to early Cenozoic calcite veins. Our analysis indicates that the formation temperatures were preserved in the clumped isotopic compositions (16-45 °C), whereas the OIT temperatures were shifted to lower temperatures (- 2 to 33 °C). An OIT temperature shift occurred, due to a retrograde oxygen isotope exchange between the fluid inclusion water and the host calcite. These results imply that the retrograde isotope exchange should be taken into consideration, even for low-temperature carbonate deposits, if a sufficiently long time is available.
了解地质矿床的形成温度对于研究其成因至关重要。氧同位素测温法（OIT）利用主碳酸盐矿物与捕获在流体包裹体中的成矿水之间氧同位素分馏的温度依赖性，以及基于碳和氧聚集程度的团簇同位素测温法，正受到越来越多的关注。然而，只有少数研究应用了这些方法的组合，并且它们的数据库有限。在本研究中，我们比较了从18个中生代至早新生代方解石脉样品中获得的氧同位素测温法和团簇同位素温度。我们的分析表明，形成温度保存在团簇同位素组成中（16 - 45°C），而氧同位素测温法温度则移至较低温度（-2至33°C）。由于流体包裹体水与主方解石之间发生逆向氧同位素交换，导致了氧同位素测温法温度偏移。这些结果表明，即使对于低温碳酸盐矿床，如果有足够长的时间，也应考虑逆向同位素交换。
