Evolution of the Tyrone ophiolite, Northern Ireland, during the Grampian–Taconic orogeny: a correlative of the Annieopsquotch Ophiolite Belt of central Newfoundland?
Bibliographic record
Abstract
The Tyrone Plutonic Group of Northern Ireland represents the upper portions of a tectonically dissected suprasubduction-zone ophiolite accreted to the composite Laurentian margin during the Middle Ordovician. Understanding its development and relationship to the Tyrone Central Inlier, an outboard fragment of relatively high-grade, peri-Laurentian continental crust, is essential for reconstructing the closure of the Iapetus Ocean. The Tyrone Plutonic Group is composed of tectonized layered, isotropic and pegmatitic gabbros, sheeted dolerite dykes and rare pillow lavas. New U–Pb zircon thermal ionization mass spectrometry geochronology has yielded an age of 483.68 ± 0.81 Ma from pegmatitic gabbro. Geochemical characteristics, Nd and Sr isotope systematics, and zircon inheritance indicate that the Tyrone Plutonic Group formed above a north-dipping subduction zone, by the propagation of a spreading centre into a microcontinental block. Synkinematic, calc-alkaline tonalitic to granitic material preserved in the contact zone between the Tyrone Plutonic Group and the Tyrone Central Inlier has produced pressure estimates of 2.3–4.0 ± 0.6 kbar and temperatures of 525–610 °C. Coeval arc–ophiolite accretion at c . 470 Ma may explain how sillimanite-grade metamorphic conditions were reached locally in the underlying Tyrone Central Inlier. Strong temporal, geochemical and lithological similarities exist to the Annieopsquotch Ophiolite Belt of Newfoundland. Supplementary materials: Petrographic photographs, whole-rock, isotopic and mineral geochemical data, and U–Th–Pb isotopic data are available at www.geolsoc.org.uk/SUP18646 .
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".