Biomagnetostratigraphy of the Vikinghøgda Formation, Svalbard (Arctic Norway), and the geomagnetic polarity timescale for the Lower Triassic
Bibliographic record
Abstract
A bio-magnetostratigraphy for the Lower Triassic is constructed, using the ammonoid biostratigraphy from arctic Boreal successions. Combined thermal and alternating field demagnetisation determines the Triassic magnetic field polarity in 86% of specimens, with 36% showing linear trajectory line-fits and the remainder great circle trends towards the characteristic magnetisation. Mean pole directions for the Deltadalen (=50°, φ=159°, dp/dm=3.9°/5.1°), Lusitaniadalen (=56°, φ=163°, dp/dm=4.4°/5.4°) and Vendomdalen (=57°, φ=143°, dp/dm=4.4°/5.4°) members fall close to the European Lower Triassic apparent polar wander path. Mean directions for two of these member-means pass the reversal test. The remanence is predominantly carried by magnetite. The polarity stratigraphy, when integrated with the ammonoid and meager conodont data is similar to that determined from successions in the Sverdrup Basin (Canada). The Permian-Triassic boundary post-dates a pronounced palynofloral turnover, and pre-dates a short duration reverse magnetozone (LT1n.1r). In the correlated Shangsi section (in S. China) LT1n.1r occurs after the FAD of H. parvus, but in the arctic is within the Otoceras boreale Zone. The late Griesbachian to early Smithian is mostly reverse polarity, with three normal polarity intervals, overlain by mid and late Smithian normal polarity. The Spathian contains four reverse polarity intervals, the oldest one within the early Spathian with the remainder in the late Spathian. Transition into the Anisian is within the uppermost reverse magnetozone, a feature documented in other sections of this age. The polarity pattern is correlated to other marine sections, indicating the robustness of the bio-magnetostratigraphic composite and its utility in calibrating Lower Triassic time.
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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".