Crustal architecture of SW Yukon, northern Cordillera: Implications for crustal growth in a convergent margin orogen
Bibliographic record
Abstract
A structural analysis of southwest Yukon based on mapping and the compilation of structural data is used to determine if convergent margin orogenesis has contributed to westward growth of North America. The crust of SW Yukon is tilted regionally to the ESE, exposing a >20 km section of crust. A down‐plunge profile is used to determine the geometry and evolution of the crust. Four lithotectonic packages are recognized. These are, from east to west, (1) the Triassic‐Jurassic Whitehorse Trough assemblage of arc and arc‐derived volcanic and sedimentary rocks, (2) the Devonian‐Mississippian continental Aishihik metamorphic assemblage, (3) the Jurassic‐Cretaceous metapelitic Kluane metamorphic assemblage, and (4) the Jurassic‐Cretaceous Dezadeash Group of arc‐marginal graywackes. The Early Jurassic Aishihik and Tertiary Coast plutonic suites are major synkinematic tabular intrusive complexes that facilitated crustal growth by subcretion of the Aishihik metamorphic assemblage beneath the Whitehorse Trough and the Kluane metamorphic assemblage and Dezadeash Group beneath Aishihik metamorphic assemblage and overlying strata, respectively. Early Jurassic crustal growth gave rise to a crust that became older and more radiogenic at depth; Tertiary growth gave rise to a crust that became younger and less radiogeneic at depth. Crustal growth by subcretion necessarily involved the removal of the lower crust and mantle of the upper plate. The lithotectonic assemblages and the tabular intrusive complexes along which they were assembled are identifiable in the seismic reflection data along Slave Northern Cordillera Lithosphere Evolution Project (SNORCLE) line 3 and are broadly imaged by a regional electromagnetic (EM) survey. The ACCRETE program to the south has documented a comparable and directly correlative crustal geometry across the Great Tonalite Sill. Our findings are inconsistent with crustal growth models of tectonic flakes being emplaced onto an autochthonous lower crust and mantle. Instead our findings support models (Lithoprobe Vancouver Island, and ACCRETE) of crustal growth at convergent margins as resulting from synmagmatic subcretion.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".