Harvey-Cardiff domain and its relationship to the Composite Arc Belt, Grenville Province: insights from U–Pb geochronology and geochemistryThis article is one of a series of papers published in this Special Issue on the theme of <i>Geochronology</i> in honour of Tom Krogh.
Bibliographic record
Abstract
Combined mapping, U–Pb isotope dilution – thermal ionization mass spectrometry (ID–TIMS) geochronology and geochemical studies in Harvey-Cardiff domain in the western Composite Arc Belt reveal the presence of a long-lived magmatic–metamorphic history between 1290 and 1030 Ma. Following intrusion of gneissic tonalite of the Anstruther and Burleigh gneiss complexes at ca. 1290 Ma, diorite of the Salmon Burn intrusive complex was emplaced at 1242.1 ± 1.1 Ma. A potassium-feldspar megacrystic monzogranite in the Salerno Creek deformation zone that forms the boundary between Harvey-Cardiff domain and Bancroft terrane was emplaced at 1211.3 ± 1.5 Ma, similar to the 1220 ± 1.6 Ma old Junction pluton and a previously reported age of ca. 1229 Ma from another Methuen suite granite in the domain. All three ages are 20 to 30 million years younger than Methuen suite ages elsewhere in the Composite Arc Belt (1250–1240 Ma). Deformation along the Salerno Creek deformation zone is constrained between 1211 Ma, the age of the megacrystic monzogranite, and 1050 Ma, the age of titanite grains from the Salmon Burn intrusive complex and a late alkalic dike. A monzogranite of the newly recognized Catchacoma granite suite yielded an age of 1067 ± 3.7 Ma, similar to the 1059.2 ± 1.6 Ma age obtained from the Cavendish pegmatite vein. These ages suggest a temporal link between late granite and pegmatite emplacement in Harvey-Cardiff domain. Metamorphic zircon, monazite, and titanite ages fall into three clusters (1082–1070, 1063–1045, and 1037–1030 Ma) and may represent a protracted metamorphic event or reflect distinct pulses during the Ottawan orogeny.
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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 | 0.001 |
| Science and technology studies | 0.001 | 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".