Dating Old Groundwater with <sup>36</sup>Cl and <sup>81</sup>Kr in a Fractured Claystone Formation, Mecsek Mts., Hungary
Bibliographic record
Abstract
The age distribution of groundwater retrieved in two boreholes of a claystone formation in the Mecsek Mountains, Hungary, was investigated using age tracers 81 Kr and 36 Cl, with additional analyses of 4 He, 14 C, and tritium. The present work aims to search a potential site for a high-level radioactive waste repository. Tracer age results provide significant insights into the temporal evolution of the vertical recharge. Radiogenic 4 He concentration increases with depth, and 3 He/ 4 He ratios decreasing toward crustal support the hypothesis of an increasing age with depth. Shallow borehole samples reveal a broad age range, including one with an 81 Kr model age of approximately 34,000 years, and a 14 C model age of 13,400 years. In deeper sections, a 81 Kr model age of 625,000 years was broadly consistent with a 36 Cl model age of ∼400,000 years, indicating the presence of ancient groundwater. Unexpectedly high 81 Kr abundances measured in one borehole indicate underground 81 Kr production in a uranium-rich rock formation, adding to uncertainty of 81 Kr model ages, whereas the obtained 36 Cl ages (∼90,000 to ∼400,000 years) are here considered more reasonable. Noble gas temperatures indicate that recharge occurred during glacial and interglacial periods. This study demonstrates the value of integrating multiple isotopic tracers to address uncertainties in groundwater dating and to provide a robust framework for understanding deep aquifer systems.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".