Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada
Bibliographic record
Abstract
The St. Cyr area near Quiet Lake hosts well preserved to variably retrogressed eclogite found as sub-metre to hundreds of metre-long lenses within quartzofeldspathic schist in south-central Yukon, Canada. The St. Cyr klippe consists of structurally imbricated, polydeformed and polymetamorphosed units of continental arc crust and ultramafic–mafic rocks. Eclogite-bearing quartzofeldspathic schist forms thrust slices in a 30 km long by 6 km wide, northwest-striking outcrop belt. The schist unit comprises metasedimentary and felsic intrusive rocks that are intercalated on the metre to tens of metres scale. Ultramafic rocks, serpentinite and associated greenschist-facies metagabbro form imbricated tectonic slices within the eclogite-bearing quartzofeldspathic unit, which led to a previously held hypothesis that eclogite was exhumed within a tectonic mélange. The presence of phengite and Permian zircon crystallized under eclogite-facies metamorphic conditions in the quartzofeldspathic host rocks indicate that the eclogite was metamorphosed in situ together with the schist as a coherent unit that was part of the continental arc crust of the Yukon–Tanana terrane, rather than a mélange associated with the subduction of oceanic crust of the Slide Mountain terrane. Petrological, geochemical, geochronological and structural similarities link St. Cyr eclogite to other high-pressure localities within Yukon, indicating the high-pressure assemblages form a larger lithotectonic unit within the Yukon–Tanana terrane.RÉSUMÉLa région de St-Cyr renferme des éclogites bien conservées à légèrement rétrogradées qui se présentent sous forme de lentilles allant de la fraction de mètre à quelques centaines de mètres de longueur, au sein d’un schiste quartzofeldspathique du centre-sud du Yukon au Canada. La klippe de St-Cyr est structurellement constituée d’unités imbriquées, polydéformées et polymétamorphisées de croûte d’arc continental et de roches ultramafiques à mafiques. Les schistes quartzofeldspathiques à lentilles d’éclogites forment des écailles de chevauchement d’une bande de 30 km de longueur par 6 km de largeur de direction nord-ouest. Les schistes sont constitués de roches métasédimentaires et de roches intrusives felsiques intercalées à des intervalles qui vont du mètre à quelques dizaines de mètres. Les roches ultramafiques, serpentinites et métagabbros au facies à schiste vert forment des écailles tectoniques imbriquées au sein de l’unité quartzofeldspathique à lentilles d’éclogite, d’où une précédente hypothèse voulant que les éclogites soient un produit d’exhumation à partir d’un mélange tectonique. La présence de phengite et de zircon permien cristallisé sous conditions métamorphiques du faciès à éclogite au sein de la roche hôte quartzofeldspathique indiquent que l’éclogite a été métamorphisée en place, avec le schiste comme unité cohérente du terrane de croûte d’arc continental de Yukon–Tanana, plutôt qu’un mélange associé à une subduction de croûte océanique du terrane de Slide Mountain. Des similarités pétrologiques, géochimiques, géochronologiques et structurales lient les éclogites de St-Cyr à d’autres lieux de hautes pressions au Yukon, ce qui indique que les assemblages de hautes pressions forment une unité lithotectonique plus grande au sein du terrane de Yukon–Tanana.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 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".