A Devonian >2000-km-long dolerite dyke swarm-belt and associated basalts along the Urals-Novozemelian fold-belt: part of an East-European (Baltica) LIP tracing the Tuzo Superswell
Bibliographic record
Abstract
Two dolerite dyke swarms are recognized along and paralleling the Ural Mountains, Russia. The Uralian swarm is 1400-km long (2300-km long if traced from its inferred plume centre). Further north, the Pay-Khoy swarm can be traced through the Pay-Khoy–Novaya Zemlya fold belt for a distance of c. 250 km (800-km long if traced from its inferred plume centre). An Upper Devonian age for volcanism associated with the Pay-Khoy swarm is well constrained by isotopic data. A Devonian age for the Uralian swarm was until now supported mainly by broad geological field relationships between the dykes and host rocks, i.e. dykes locally cut Proterozoic, Ordovician to Devonian sedimentary rocks, but never Carboniferous sequences. Rare isotopic age determinations also support an Upper Devonian age for the weakly altered dykes. Herein, a new precise U–Pb baddeleyite age determination of 377.2 ± 0.9 Ma is reported from a large (>50-m wide) gabbro–dolerite dyke cutting the uppermost Proterozoic in the Middle Urals. This result confirms a predicted Upper Devonian age for the dyke and gives additional support to the Devonian age of the Uralian swarm. Given this precise U–Pb age, the Uralian swarm is correlated with the Pay-Khoy swarm, Devonian basalts which are widely distributed across the East European (Baltica) Craton, as well as alkaline magmatic rocks and kimberlites of more restricted distribution. Collectively, this Devonian magmatism can be combined into a Kola–Dnieper Large Igneous Province (LIP) with two proposed mantle plume centres: (1) a southern centre at the intersection of the Dnieper-Donets aulacogen and Uralian swarm and (2) a northern centre in the Barents Sea, at the convergence between the Pay-Khoy dyke swarm and an unnamed swarm extending from the northern coast of the Kola Peninsula, as well as converging rift/graben zones. Furthermore, this Kola–Dnieper LIP of the East European (Baltica) Craton, with its two plume centres, is approximately coeval with the Yakutsk–Vilyui LIP and its plume centre on the eastern side of the Siberian Craton. These two LIPs were in close proximity at that time and their three plumes may represent a superplume derived from an active part of a single deep mantle LLSVP (Large Low Shear Wave Velocity Province), the so-called Tuzo superswell.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".