Magnetic fabric studies of the Nipissing sill province and Senneterre dykes, Canadian Shield, and implications for emplacement
Bibliographic record
Abstract
The 2.21 Ga Nipissing diabase sills intrude the Huronian Supergroup of the Southern Province. Coeval Senneterre dykes in the adjacent portion of the Superior Province are potential feeders for the sills. Anisotropy of magnetic susceptibility (AMS) data were obtained from both of these units to study flow patterns and test emplacement models. The sills exhibit three distinct paleomagnetic directions that are likely primary and represent a time-correlation tool within the magmatic event. Two of the three directions are also found in Senneterre dykes. Sites in the northern Cobalt Embayment carry an N1 (reverse) paleomagnetic signature. They possess maximum AMS axes that trend north-northwest–south-southeast, interpreted as the direction of magma emplacement. In one area, the data rule out a cone sheet emplacement mechanism. The N3 paleomagnetic signature is restricted to a sill and (or) dyke-like bodies near Lake Timiskaming, where the AMS axes are dominantly north-northwest–south-southeast, similar to that of the nearby N1 (reverse) sites. Sites in a geographically restricted area farther south carry an N1 (normal) paleomagnetic direction. The AMS patterns in these sites exhibit very poor within- and between-site consistency, compatible with the magma having crystallized statically in this volumetrically minor magmatic pulse. In the Sudbury – Elliot Lake area, the Nipissing diabase is deformed, and outcrops exhibit east–west elongation parallel to the fold axes of the enclosing Huronian sedimentary rocks. AMS fabrics are interpreted as reflecting this deformation rather than primary magmatic flow. Three of eight Senneterre dyke sites show horizontal flow patterns, whereas the remainder have more complicated AMS patterns.
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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 | 0.003 | 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) | 0.001 | 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".