Geology of the Three Ladies Mountain/Mount Stevenson area, Quesnel Highland, British Columbia
Bibliographic record
Abstract
In late Proterozoic to early Paleozoic time, continent-derived clastic sediment and minor carbonate of the Snowshoe Group were deposited in a continental slope to shelf environment, and shallow marine elastics and carbonates of the Cariboo Group were deposited nearer to the shore of North America. The Snowshoe Group is divided into a lower sequence of micaceous quartzite, pelite, and minor amphibolite, all interlayered with quartz diorite sheets; and an upper sequence of micaceous quartzite, pelite, and carbonate with minor calc-silicate and amphibolitic rocks. Early isoclinal (F1A) and NE-verging tight folds (F1B) formed together with a metamorphic foliation. Tight to normal, cylindroidal second phase (F2) folds, characterized by SW-vergence and NW plunge, formed during the mid-Jurassic Columbian orogeny at about the same time as accretion of suspect terranes southwest of the map area. Prograde metamorphism in the Barrovian series of amphibolite facies was synkinematic to postkinematic to F2 folding, with maximum metamorphic recrystallization outlasting deformation. Garnet-biotite geothermometry indicates temperatures of 525 ± 20°C for pelites near the kyanite to sillimanite zone isograd. Garnet-aluminosilicate-ilmenite geobarometry limits P to less than 7 kb. Grossular-anorthite-aluminosi1icate geobarometry gives P = 5.5 ± 0.7 kb. Retrograde metamorphism and F3 kink-folding occurred during uplift, followed by broad warping (F4) with NE trend. The low-angle, postmetamorphic Little River Fault emplaced chlorite to biotite zone phyllite and carbonate of the Cariboo Group, in the hanging wall, against staurolite-kyanite to sillimanite schists and gneisses of the Snowshoe Group, in the footwall, with latest movement of the hanging wall in an ESE direction. A Rb-Sr model depositional age of approximately 750 Ma, assuming an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.708, was obtained for Snowshoe Group metasedimentary rocks. Paleozoic plutonism is indicated by a Rb-Sr whole-rock isochron date of 530 ± 94 Ma with initial ⁸⁷Sr/⁸⁶Sr ratio of 0.706, and U-Pb dates on zircon, indicating a minimum age of 335 Ma and maximum age of about 450 Ma, for quartz dioritic gneiss intrusive into the Snowshoe Group early in its deformational history, pre-F1B folding. Late- to post-metamorphic pegmatite cooled through 400-500°C at 86 ± 3 Ma. The age of the Little River Fault is bracketed between intrusion of pegmatite and a Miocene(?) erosion surface.
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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 | 0.002 | 0.003 |
| Science and technology studies | 0.003 | 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) | 0.007 | 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".