U-Pb geochronology and geochemistry from the northeastern New River belt, southern New Brunswick, Canada: significance of the Almond Road Group to the Ganderian platformal margin
Bibliographic record
Abstract
The Almond Road Group in the northeastern New River belt comprises two formations: the basal Snider Mountain Formation contains orthoquartzite, feldspathic quartzite, and quartzite pebble conglomerate; the gradationally overlying Ketchum Brook Formation is composed of feldspathic sandstone, laminated dark siltstone and shale, overlain by mafic lithic tuffs and basaltic flows. The Almond Road Group overlies latest Ediacaran to earliest Cambrian (early Fortunian) pyroclastic, volcaniclastic, and epiclastic rocks of the Belleisle Bay Group. Based in part on this relationship, the Almond Road Group was thought to be Early Cambrian, although an upper age limit had never been determined. A U–Pb (zircon) age of 475 ± 2 Ma for the West Scotch Settlement porphyry, a small felsic hypabyssal intrusion emplaced into the Ketchum Brook Formation, demonstrates that the Almond Road Group is no younger than Early Ordovician (early Floian) age. Its age is further constrained by LA ICP-MS detrital zircon data from a basal quartzite in the Snider Mountain Formation. Results show a dominant peak in the Ediacaran (ca. 575 Ma), with the youngest coherent cluster of ages at ca. 530–520 Ma. Together these data support a Cambrian age for the quartz-rich Almond Road Group and its platformal relationship to Ganderia.
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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 | 0.002 | 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) | 0.002 | 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".