STABLE CARBON AND OXYGEN ISOTOPIC STUDY OF IMPACT-INDUCED HYDROTHERMAL CALCITE AT THE HAUGHTON IMPACT STRUCTURE, DEVON ISLAND, NUNAVUT, CANADA
Bibliographic record
Abstract
From over 60 terrestrial impact craters with evidence of impact-induced hydrothermal\nalteration, only a dozen have been examined for stable isotopic compositions of\nhydrothermal carbonates. A variety of impact-induced carbonate precipitates have been\nidentified at the Haughton impact structure (23 km, 39 Ma) on Devon Island, Canadian\nArctic. The hydrothermal carbonates are found in three distinct settings: (1) as fracture\nfillings in shocked lithologies of the inner crater; (3) as vug fillings within impact melt\nbreccias, and (3) as interstice fillings in pipe structures of the crater rim. X-Ray Powder\nDiffraction, X-Ray Fluorescence and carbon and oxygen stable isotope analyses were\nperformed on rock and calcite mineralisation samples. Values of ô13Ccaicite range from\n-14 to -2%o, indicating an inorganic carbon source. Values of 6 Ocaicite range from\n1o\n+8 to +18 %o, corresponding to a 5 OflUid of -7 to +2%o, most likely an enriched polar meteoric source at temperatures of mineralisation >130°C.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 source (direct Gemma or distilled Codex), 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".