Interpretation of Pb and S Isotope Data for the Ganesh Himal Metamorphosed Stratiform Zn-Pb Deposit, Central Nepal Himalaya
Bibliographic record
Abstract
Abstract The Ganesh Himal Zn-Pb deposit in central Nepal has been highly deformed and metamorphosed together with its host rocks. Pb isotope data for the deposit are interpreted to define an age of about 875 to 785 Ma, which is permissive of age equivalence to the upper Vindhyan Supergroup of the north-central and northwestern Indian Shield. The slightly positive to slightly negative sulphur isotope values for the Ganesh Himal deposit are in accord with coeval seawater sulphate δ34S values in the range +15 to +20 ‰, and thus with an age greater than about 650 Ma. Apparent equilibrium sulphur isotope fractionation temperatures for sulphide pairs are generally 500 °C to 750 °C, a range that agrees with kyanite-staurolite and biotite-staurolite assemblages. The 875 to 785 Ma age for Ganesh Himal has been calculated on the basis of Pb isotope ratios and age data for other Neoproterozoic and Cambrian sediment-hosted deposits. These Ganesh Himal results and those for the Genekha deposit, Bhutan, help confirm the previously postulated widespread distribution of Vindhyan rocks in Himalayan metasedimentary belts. The available Pb isotope and age data for the Amjhor deposit, in Upper Vindhyan rocks in Bihar State, India, are suggestive but not confirmatory of a tentative conclusion that the Ganesh Himal deposit is its age equivalent.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".