Local Rotations Biasing Supercontinental Configurations: Revisiting a Key ca. 780 Ma Paleomagnetic Pole for Laurentia and Rodinia
Bibliographic record
Abstract
Abstract Tonian paleomagnetic data underpin quantitative Rodinia supercontinent reconstructions centered on Laurentia, but poles from orogenic regions such as the North American Cordillera can only be utilized confidently if local rotations are shown to be negligible. The ca. 780‐Ma Gunbarrel large igneous province is a case in point, exposed across thousands of km of the Cordilleran external zone. Here we present a paleomagnetic study of nine ca. 780 Ma mafic dikes in the Beartooth Mountains, Wyoming craton, and one mafic sheet from the Slave craton. A revised ca. 780 Ma pole with positive baked contact tests was obtained by averaging the 10 virtual geomagnetic poles (VGPs) from this study and VGPs from four intrusions previously reported from stable Laurentia. This new pole and the ca. 780 Ma pole from the Tobacco Root Mountains suggest that the latter region experienced a local ∼27° clockwise rotation, as additionally supported by comparisons of Laurentian poles from ca. 1,590 and ca. 1,450 Ma. The timing of the Tobacco Root rotation is constrained to 78–54 Ma using Cenozoic paleomagnetic data and regional cross‐cutting relationships of bounding fault structures. Now relying on the new Gunbarrel pole with coeval results from other cratons, a revised configuration of the paleo‐northern sector of Rodinia at ca. 780 Ma is proposed. The new configuration elucidates the blocks' paleogeographic relationships and provides critical constraints on exploring the coevolution of paleogeography, climate, and life.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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".