Mineralogical, sulphur, and lead isotopic study of the Lemarchant Zn-Pb-Cu-Ag-Au-VMS deposit: implications for precious-metal enrichment processes in the VMS environment
Bibliographic record
Abstract
The Lemarchant deposit is a Cambrian volcanogenic massive sulphide (VMS) deposit located in the Central Mobile Belt of the Newfoundland Appalachians. Unlike other polymetallic VMS deposits in the bimodal felsic Tally Pond group, Lemarchant is enriched in precious metals. The deposit is composed of contrasting styles of sulphide mineralization, and formed in three discrete stages: Stage 1: barite-rich, low-temperature (<250oC) VMS mineralization; Stage 2: 150 to 250oC intermediate- to high-sulphidation epithermal-style mineralization; and Stage 3: polymetallic, high-temperature (>300oC) VMS mineralization. Sulphur isotopes suggest that S is derived from three sources: thermochemically reduced seawater sulphate, leached igneous basement rock, and magmatic SO2. Lead isotopes indicate that Pb is primarily derived from evolved crustal material, with some input from juvenile volcanic rock (i.e. arc-rift). Precious metals associated with epithermal-style mineralization are consistent with a magmatic contribution to the hydrothermal fluid. Precious metals were precipitated from intermittently boiled fluids, at relatively shallow (<1500 m) water depth.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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".