Arsenopyrite Re-Os age and zircon U-Pb geochronology of gold prospects, Caniapiscau-Koksoak area, northern Labrador Trough, Quebec
Bibliographic record
Abstract
The Labrador Trough of northern Quebec is perhaps best known for its giant iron ore deposits, but shows exploration potential for several other deposits types, including orogenic-style gold. In the Caniapiscau-Koksoak area, gold showings are commonly associated with late structural features in mafic to intermediate intrusive rocks and their vicinity, but the timing of mineralization is unclear. In this study, we provide geochronology results on two samples. A gold-bearing arsenopyrite mineral separate from a vein in the Golden Tooth structure (Willbob property) was dated by Re-Os using negative thermal ionization mass spectrometry (N-TIMS). A weighted average model age of 1810.7 ± 4.6 Ma was obtained, representing the first direct dating of gold mineralization in the Labrador Trough. It is interpreted as the age of structurally controlled, Montagnais sill-hosted vein-style gold mineralization in the northern part of the Trough and fits within the known age of the Trans-Hudson orogeny. At the Golden Tooth showing, the mineralized veins are interpreted to have formed during the last deformation episode in the region, D4. To provide additional geological context for the area a conglomerate from the Baby Formation (Koksoak Group) sampled on the Kan property was dated by U-Pb on zircons using a sensitive high-resolution ion microprobe (SHRIMP) and gives an estimate of the maximum age of deposition for the conglomerate at 2619 ± 11 Ma. This contrasts with regional geologic knowledge and clasts composition, which suggests that the Baby Formation is Paleoproterozoic in age rather than Archean.
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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 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.007 | 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".