Proterozoic diabase sills of northern Ontario: Magnetic properties and history
Bibliographic record
Abstract
Magnetic fabrics show that a series of massive diabase sills (“Logan sills”) possess flow fabrics away from the midcontinental Proterozoic rift system, near its triple junction on the north shore of Lake Superior. Their intense remanences are commonly antiparallel to the geomagnetic field, requiring some knowledge of natural remanent magnetization in order to interpret of ground magnetic surveys. Thermal demagnetization, low‐temperature demagnetization, and the combined techniques yield differently oriented characteristic remanence vectors in some of these sills. Although the commonly reported “Keweenawan” reversed paleofield direction is verified by most A components, the orientation of vectors within sites and through the thickness of sills is large and may be attributed to reversals, excursions, and secular variation. B components are mostly down, but their orientation distribution is poorly concentrated. Low‐temperature demagnetization, prior to thermal demagnetization, tends to improve the consistency of vectors defined in subsequent thermal demagnetization. Moreover, in some cases, three to five cycles of low‐temperature demagnetization alone produces the same result as the more time‐consuming thermal demagnetization. Some within‐site scatter of the A components is large, and some anomalous specimen directions and alternate polarities may be associated with platinum group mineralization. Whereas the grand mean direction for all sites lies on the available apparent polar wander path between 1100 and 1300 Ma, the mean paleopole locations differ at the 95% level for different demagnetization treatments of specimens from the same sites.
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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) | 0.003 | 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".