Geochronology of a granitoid boulder from the Corsewall Formation (Southern Uplands): implications for the evolution of southern Scotland
Bibliographic record
Abstract
Synopsis A U–Pb monazite age of 474 ± 2 Ma has been determined for a weakly foliated granite boulder > 1 m in diameter from the Corsewall conglomerate, SW Scotland. The clast contains xenoliths and partly assimilated xenoliths of regionally metamorphosed rock from which the monazites have been derived. The age constrains the original emplacement of the pluton to between 474 ± 2 and c. 458 Ma, the age of the deposit in which the boulder is found. This age confirms an earlier Rb–Sr muscovite Ordovician age for boulders of this type and contradicts a pre-existing age of 1265 Ma used to suggest a source in Newfoundland and a post-Caradoc major lateral displacement of the Southern Uplands. The monazite age reaffirms that a basement-arc complex once existed north of the Southern Uplands and was the principal contributor of sediment to Ordovician–Silurian basins of southern Scotland. A source for the metamorphic detritus in the Dalradian block is unlikely, as the boulders would have been transported for > 150 km through zones of actively accreting terranes and marginal basins. The possibility of Archaean crust within this basement complex is further suggested by the Sm–Nd systematics of the granite boulders at Corsewall Point.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".