Field relationships, petrology, and tectonic setting of Neoproterozoic plutonic rocks in the southern Cobequid Highlands, Nova Scotia
Bibliographic record
Abstract
Geological mapping combined with U-Pb (zircon) dating and petrological work have resulted in revised interpretations of Neoproterozoic plutonic rocks in the southern Cobequid Highlands. The Frog Lake, Debert River, and McCallum Settlement plutons, as well as the western part of the Gain Brook pluton, consist of the same three components in varying proportions: dioritic rocks, tonalitic to granodioritic rocks, and granitic rocks ranging from monzogranite to alkali-feldspar granite. Based on petrographic and chemical characteristics, the dioritic rocks are comagmatic low-potassium tholeiite suite showing Fe- and Ti-enrichment trends. The tonalitic, granodioritic, and granitic rocks display similar chemical trends and constitute a comagmatic calc-alkalic suite. Both the tholeiitic dioritic rocks and the calc-alkalic intermediate to felsic rocks formed in a volcanic-arc setting, but lack of chemical continuity between them indicates that they are not comagmatic. However, mingled relationships and previously published and new U-Pb (zircon) ages indicate that they are the same age and likely formed in the roots of the same volcanic arc at ca. 615-605 Ma. Hence it is suggested that they be collectively renamed the Bass River plutonic suite. In contrast, the Gunshot Brook pluton in the eastern Cobequid Highlands, although apparently of similar age, displays petrological differences and is not included in the suite. The older Economy River Orthogneiss is chemically distinct and likely part of the previously identified ca. 750-730 Ma Mount Ephraim Plutonic Suite. The Bass River plutonic suite is similar in age and chemical character to some plutons in the northern Cobequid Highlands, Antigonish Highlands, and southeastern New England, and these areas may have been originally together, forming a distinctive part of West Avalonia.
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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) | 0.001 | 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".