Petrology, tectonic setting, and mineralization potential of late Devonian plutons in the central Cape Breton Highlands, Nova Scotia
Bibliographic record
Abstract
The West Branch North River (WBNR), Bothan Brook (BB), Centre Road (CR), and Peters Brook (PB) plutons are in the eastern Aspy terrane of central Cape Breton Island, part of Ganderia in the northern Appalachian orogen. The plutons are undeformed and were intruded after regional (Acadian) deformation and metamorphism in their host rocks. Their distinctive elongate shapes are the result of mainly post-shear emplacement in major shear zones related to juxtaposition of the Bras d’Or and Aspy terranes and hence their ages of ca. 375 Ma (BB and WBNR) and ca. 360 Ma (CR) constrain timing of major shear zone movement. The age of the PB pluton is uncertain. Petrographic examination of cut rock slabs and thin sections from about 50 samples showed a wide range in rock types. Samples from the WBNR, BB, and PB plutons range from medium- to coarse-grained equigranular biotite granodiorite to monzogranite, whereas the Centre Road pluton consists of mappable areas of monzodiorite, quartz monzodiorite, and granodiorite/monzogranite. Chemical analyses of 42 samples show a range in SiO2 from about 51% to 77% with lowest contents in the CR pluton and highest in the BB pluton. High K2O in most samples suggests that they have shoshonitic affinity. Total REE content and light REE enrichment are highest in the CR pluton and lowest in the BB pluton. The plutons generally display I-type chemical characteristics, and trace element compositions indicate that the magmas formed in a post-collisional slab-failure tectonic setting. The tectonic setting of the BB and WBNR plutons are consistent with that of the S-type Park Spur pluton, and chemistry and tectonic setting suggest a magmatic link of the CR pluton with the more evolved Margaree pluton. Although no mineralization has been observed, the presence of pegmatite in the CR pluton and highly evolved compositions in the BB pluton suggest some potential for Cu, Li, or other critical elements.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| 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) | 0.002 | 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".