A reversal of the Earth's magnetic field recorded in mid‐Miocene lava flows of Gran Canaria: Paleodirections
Bibliographic record
Abstract
A paleomagnetic investigation has been carried out on a continuous series of 87 volcanic lava flows from the mid‐Miocene shield basalts of Gran Canaria. The sequence covers a reversal of the Earth's magnetic field from reverse to normal. Intermediate directions of the field are recorded in 34 lava flows. During the reversal the virtual geomagnetic poles (VGPs) show an accumulation in three consecutive areas: southeast of South America, east of India, and in the central Pacific. In addition to the reversal three excursions are recorded in the sequence, two preceding and one succeeding the reversal. The intermediate directions of the excursion just before and after the transition have the same VGP positions as the first and the last accumulation zone, respectively. From radiometric age constraints this transition corresponds very likely to a ∼14.1 Ma field reversal. The remarkable returns to the same transitional positions near South America and the central Pacific indicate preferred locations of the VGP during the transitional stages. Only the South America cluster can be correlated to VGP clusters observed in other reversals of the last 10 Myr and to lower mantle seismic anomalies. The VGPs in the Pacific track instead along the antipode of the site longitude. This indicates that mechanisms other than lower mantle heterogeneities additionally affect the transitional record of the sampled sequence and zonal harmonics are plausible candidates.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".