Age and origin of advanced argillic alteration zones and related exotic limonite deposits in the Limonite Creek area, central British Columbia
Bibliographic record
Abstract
The Limonite Creek property in north-central British Columbia contains several zones of silicic and acid-sulphate alteration. These zones grade through advanced argillic and aluminous mineral assemblages to sericitic and regional propylitic alteration. Alteration assemblages are characteristic of high-sulphidation systems, although the abundance of pyrophyllite and andalusite suggests formation at depths below typical epithermal environments. Alteration occurred between 212 and 52 Ma as determined from field relations and U-Pb dating of intrusions. The deformed nature of the alteration assemblages and a minimum age of alunite (144 ± 8 Ma) suggest formation in latest Triassic to Middle Jurassic time. Based on these age constraints, alteration zones at Limonite Creek are significantly older than the Eocene Equity Silver deposit (ca. 60 Ma), despite the latter's proximity and similar styles of alteration. Based on the new dates, host rocks at Limonite Creek are Late Triassic or older, and hence regional stratigraphy needs reassessment. Extensive exotic limonite deposits occur around the alteration zones and at lower elevations to the south. Radiocarbon dating indicates that the deposits have been accumulating for at least 8000 years. Iron released during weathering was transported in low-pH waters and precipitated initially as ferrihydrite, with subsequent conversion to goethite. Water chemistry confirms that the process is still active. In addition to iron, the limonite contains minor copper and zinc. The formation of low-pH waters and the transport of iron resulted from weathering of pyrite-rich alteration assemblages with negligible buffering capacity.
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".