Petrochemistry, mineralogy, and Nd isotopic analyses of Tithonian alkaline lamprophyric intrusions, north-central Newfoundland, Canada
Bibliographic record
Abstract
The Newfoundland Atlantic margin in Eastern Canada formed through protracted lithospheric extension, subsequent rifting, and ultimately, breakup. Mesozoic–Cenozoic magmatism on and offshore Newfoundland coincided with, and potentially resulted from, the concurrent rifting and breakup. In north-central Newfoundland, the alkali monzogabbroic Budgell Harbour and Dildo Pond stocks, an accompanying lamprophyre dyke swarm, and a peridotite sill collectively form the Notre Dame Bay Magmatic Province and are products of a punctuated alkaline magmatic pulse on the Newfoundland margin at ca. 148 Ma (Jurassic, Tithonian) with contemporaneous rifting and the formation of offshore petroliferous basins. The stocks comprise coarsely modally layered phlogopite–ilmenite–magnetite–kaersutite olivine gabbro or essexite. The radially disposed lamprophyre dykes are aphyric to ilmenite–magnetite–diopside ± olivine ± kaersutite ± phlogopite porphyritic camptonites containing common feldspathic- and/or carbonate-dominant ocelli. Silica-undersaturated (kirschsteinite), oxidized (esseneite, calderite), and incompatible-element-bearing minerals (barite, kainosite) form paragenetically late, small grains in the groundmass mantling other phases. Mineral chemistry, lithogeochemistry, and Nd isotopic data indicate the rocks are similar to ocean island basalt and alkaline lamprophyres and were generated via low degrees of partial melting of a Neoproterozoic, weakly garnetiferous lithospheric mantle source. The intrusions occur along the intersections of broadly northeast-trending, inherited, Appalachian-cycle lithospheric scale faults with a prominent east–west step in the northeast Newfoundland Mohorovičić discontinuity along the northeast Newfoundland coast. The convergence of inherited structures with the topographic variation of the lithosphere–asthenosphere boundary likely focussed decompression melting of the lithospheric mantle driven through distal, edge-driven upwelling associated with continued extension in the northwest Atlantic.
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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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".