Paleomagnetism of the Mississippian HP Pipe and the Western Margin of the North American Craton
Bibliographic record
Abstract
The HP pipe is a small oval (80m×40m) kimberlitic diatreme near Golden, B.C., in the fold-and-thrust belt of the Rocky Mountains. The pipe intrudes gently-dipping (∼10°S) Late Cambrian to Middle Ordovician limestones with nearly vertical contacts. It is comprised of carbonate breccia fragments and pyroxenite nodules in a light-green serpentine matrix and gives a Rb-Sr age of 348±7 Ma. A later phase of dark-green dikes cut the breccia and adjacent limestones. AF and thermal step demagnetization of 168 specimens from 42 oriented blocks was done using an automated cryogenic magnetometer in a shielded room for remanence measurement. The diatreme breccia and dikes retain a stable A remanence component after thermal cleaning above ∼400°C and AF cleaning above ∼20 mT. Their combined mean direction of 129.8°, −44.3° (α95 = 6.5°) after tilt correction gives a concordant Mississippian pole position of 138.5°E, 44.5°N (Dp = 5.1°, Dm = 8.2°). The limestones provide a positive contact test by giving a stable B component direction of 114.4°, −22.7° (α95 = 12.4°) with a concordant Late Cambrian to Middle Ordovician pole of 141.0°E, 24.3°N (δp = 7.0°, δm = 13.3°). These concordant poles indicate that the fold-and-thrust belt is part of the North American craton. Thus the suture with allochthonous terranes to the west must be located at or west of the Rocky Mountain Trench. Both the diatreme and limestones retain a low-coercivity and unblocking-temperature C component, isolated by vector subtraction without tilt correction, that records a minor overprint from the Laramide Orogeny combined with Pleistocene viscous remanence.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".