Preliminary mineralogy of barite-associated sulphide mineralization in the Ordovician Zn-Pb-Cu-Ag-Au Lemarchant volcanogenic massive sulphide deposit, Newfoundland and Labrador
Bibliographic record
Abstract
The bimodal felsic Zn-Pb-Cu-Ag-Au Lemarchant volcanogenic massive sulphide (VMS) deposit is located in central Newfoundland. Characteristic of the deposit is a mineralized barite lens that contains abundant sulphosalts and anomalous precious metals. While much of the barite is massive, bladed aggregates of barite are locally present. The mineralized barite lens consists of three mineral assemblages (or facies) that grade from the outer barite-rich mineralization toward the sulphide-rich base as follows: 1) facies A: white to honey-coloured sphalerite+pyrite+chalcopyrite+bornite>enargite±Au; 2) facies B: white sphalerite+galena+pyrite+tetrahedrite>tennantite+stromeyerite+Ag-tetrahedrite; and 3) facies C: honey-brown (and minor red) sphalerite+chalcopyrite+pyrite±galena. Iron content of sphalerite grades from higher values in the outer barite lens and proximal rhyolite, to lower values in the central barite lens. Minor visible free gold is present in barite-rich facies A mineralization. The interpreted primary mineralization sequence of these three facies begins with deposition of sphalerite and fine-grained pyrite, and penecontemporaneous crystallization of tennantite-tetrahedrite, galena, and enargite, followed by sulphide replacement by bornite and chalcopyrite, late-stage stromeyerite mineralization, and recrystallization of euhedral pyrite. The Lemarchant deposit is similar to other barite-rich, Kuroko-style VMS deposits, and is especially notable for its sulphosalt-rich mineral assemblage and precious-metal-bearing minerals. Further detailed mineral chemistry, sulphur and lead isotope analyses, and thermodynamic calculations will be undertaken to understand the siting of precious metals and the processes that resulted in precious metal enrichment at Lemarchant.
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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 | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".