Geochemistry, geochronology, and fluid inclusion study of the Late Cretaceous Newton epithermal gold deposit, British Columbia
Bibliographic record
Abstract
Newton is an intermediate-sulfidation epithermal gold deposit related to Late Cretaceous continental-arc magmatism in south-central British Columbia. Disseminated gold mineralization occurs in quartz–sericite-altered Late Cretaceous felsic volcanic rocks, and feldspar–quartz–hornblende porphyry and quartz–feldspar porphyry intrusions. The mineralization can be divided into three stages: (1) disseminated pyrite with microscopic gold inclusions, and sparse quartz–pyrite ± molybdenite veins; (2) disseminated marcasite with microscopic gold inclusions and minor base-metal sulfides; and (3) polymetallic veins of pyrite–chalcopyrite–sphalerite–arsenopyrite. Re–Os dating of molybdenite from a stage 1 vein yielded an age of 72.1 ± 0.3 Ma (published by McClenaghan in 2013). The age of the host rocks has been constrained by U–Pb dating of zircon: Late Cretaceous felsic volcanic rocks, 72.1 ± 0.6 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013); feldspar–quartz–hornblende porphyry, 72.1 ± 0.5 Ma; quartz–feldspar porphyry, 70.9 ± 0.5 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013). The mineralized rocks are intruded by a barren diorite, with an age of 69.3 ± 0.4 Ma. Fluid inclusions in quartz–pyrite ± molybdenite ± gold veins yielded an average homogenization temperature of 313 ± 51 °C (number of samples, n = 82) and salinity of 4.8 ± 0.9 wt.% NaCl equiv. (n = 46), suggesting that a relatively hot and saline fluid likely of magmatic origin was responsible for the first stage of mineralization. Some evidence for boiling was also observed in the veins. However, the bulk of the gold mineralization occurs as disseminations in the wall rocks, suggesting that wall-rock reactions were the main control on ore deposition.
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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 | 0.004 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".