A palaeomagnetic study of the Englandsháls and Lundarháls plateau lavas in Western Iceland
Bibliographic record
Abstract
As the subaerial continuation of the Mid-Atlantic ridge, Iceland’s basaltic lavas preserve Earth’s magnetic field history for the past 16 million years. Iceland’s morphologies are formed by various glacial-interglacial intervals, leaving behind glacial shaped valleys and gorges, exposing continuous lava sequences favourable for palaeo- \nmagnetic research. The first studies were carried out in the 1950s and ever since, a comprehensive magnetostratigraphy has been accomplished combining palaeomagentic data collected around Iceland. \nThis project aimed to address new directional data obtained from Lundarháls and Englandsháls plateau lavas, Western Iceland, through an investigation of their magnetic polarity with relation to the current Geomagnetic Polarity Time Scale (GPTS) by Ogg (2012). A combination of fieldwork sampling and ensuing laboratory measurements obtained directional data derived from principal component analysis (PCA) \nusing the open-source software PuffinPlot. After evaluation by carrying out Fisher statistics (see Fisher (1953)), a total of 617 from 766 samples are used for further analysis. Magnetic direction of 101 lava flows are determined, whereby their virtual \ngeomagnetic poles (VGP) are assumed to follow a geocentric dipole configuration. \nAcquired VGP positions provide a relatively continuous magnetostratigraphy. Stratigraphic logs were used to predict the number of missing lavas and correlate the sequences. The VGPs suggest three transitions towards reversed polarities, corresponding to the Mammoth subchron, Kaena subchron and the Gauss-Matuyama boundary of the GPTS. The normal polarities yield pole positions at Greenland -North Canada with excursional VGPs plotting near Japan similar to the pole path \nof the transitional flows. The reversed VGPs reveal pole positions with λp= 75°S. \nHowever, due to gaps in the sample collection and the presence of excursional lava flows (λp<45°), reversed and normal VGPs do not trend around the North and South Pole.
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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 | 0.002 | 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) | 0.001 | 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".