Grenville age deformation of the Sudbury impact structure: evidence from magnetic modelling of the Sudbury diabase dyke swarm
Bibliographic record
Abstract
Terra Nova, 24, 213–220, 2012 Abstract The Sudbury Structure is located <10 km from the Grenville Front; the northern boundary of the Grenville metamorphic terrane. Previous geological studies have suggested that late Grenvillian deformation (1000–1070 Ma) of the Sudbury Structure was limited to minor brittle deformation. Olivine diabase dykes, which were intruded at 1238 Ma, before the last pulse of Grenville deformation, cross much of the Sudbury Structure. Any Grenville age deformation of the Sudbury Structure therefore should produce systematic displacements in the geometry of the dykes. This study uses information derived from an aeromagnetic survey of the Sudbury Structure to map and measure fault displacements. Lateral displacements of dyke segments define a progressive increase in fault rotation from NE to SW across the basin. A two‐dimensional inversion modelling of magnetic anomaly profiles across segments of the dykes outlines a series of fault blocks with common dip. The dyke dip detected by the inversion models suggests that displacement on the faults included rotation about an axis perpendicular to the trend of the fault. The resulting model of scissor, or splay faults is compatible with previously published palaeomagnetic studies of the olivine dykes in the Sudbury region.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| 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".