A mid-Cretaceous alkaline volcano in the Davis Strait
Bibliographic record
Abstract
The AT2-1 well in the Davis Strait between Canada and Greenland penetrated an approximately 1.2 km thick sequence of alkaline volcanic rocks with some intercalated sediments at depths between 3690 to 4850 m. These volcanic rocks can be mapped on 2D seismic data and constitute a cone-shaped 5 km × 10 km wide and >1.2 km high structural high named the Atammik Volcano. This sequence comprises two distinct parts, an upper part of phono-tephrite to basaltic trachy-andesite and a lower part of tephriphonolite and phonolite. Rock textures and structures testify to a volcanic origin, with the uppermost units showing textural evidence of being subaerially extruded. Zircon crystals found in a sample of phonolite from 4453 m were dated by in situ laser ablation ICP–MS technique to yield ages between 98 and 93 Ma, indicating a maximum age of the formation of the phonolitic volcano of 93 Ma (Turonian). Further, detrital zircons from the clastic material have been dated yielding Archean ages. The gamma ray log indicates three internal cycles within the phonolites, each cycle displaying a stratigraphically upwards decrease in potassium content, suggesting the existence of a longer-lived system undergoing repeated magmatic differentiation and eruption events. The upper volcanic sequence is less evolved and less alkaline than the lower, suggesting a change in primary magma compositions towards progressively higher degrees of melting of the underlying mantle. This fits into a scheme of progressively higher degrees of melting with time, which in a regional context probably corresponds to a rifting event.
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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 | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".