Anomalous SedEx mineralization at the Walton Ag-Pb-Zn-Cu carbonate-hosted sulphide deposit (Nova Scotia, Canada): result of hydrocarbons?
Bibliographic record
Abstract
Walton is a past-producing Ag-Pb-Zn-Cu sulphide carbonate-hosted deposit (0.41 Mt; head grade of 350 g/t Ag, 4.28% Pb, 1.29% Zn, and 0.52% Cu) hosted primarily by sideritized Viséan Macumber Formation limestone and juxtaposed to and replacing a barite ore body (4.5 Mt of >90% barite). Previous work demonstrated that mineralization came from heated (~300°C), saline (20-28 wt. % equiv. NaCl) fluids. The present study uses optical microscopy, SEM-EDS, and major- and in situ LA-ICP-MS trace-element signatures of the host, gangue, and ore phases to refine our understanding of the mineralizing fluid system. Sideritization of the Macumber Formation occurred after dolomitization. Dolomite and siderite are generally LREE-depleted, with mostly negative Ce anomalies and prominent negative Y anomalies. Pyrite has As levels ranging from <1 ppm to 7.7 wt. % that correlate positively with Ag (values up to 2,400 ppm); the latter likely accounts for most of the Ag in the deposit. The LREE-depleted patterns of various carbonate phases indicate that the ore fluids did not equilibrate with a LREE-rich reservoir, whereas negative Ce anomalies suggest precipitation from an oxidised fluid. The positive correlation between Ag and As implies their coupling and thus a similar source and/or transport mechanism. The proposed source of metals is from hydrocarbons, now preserved as abundant petroleum inclusions, sourced in the underlying Horton Group that may have been enriched in Ag, As, and Cu. The derivation of metals from hydrocarbons could explain differences between mineralization at Walton and other carbonate-hosted sulphide deposits in Nova Scotia that do not contain significant petroleum or Ag, As, and Cu.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".