Age and Chemostratigraphy of the Finlayson Lake District, Yukon: Implications for Volcanogenic Massive Sulfide (VMS) Mineralization and Tectonics along the Western Laurentian Continental Margin
Bibliographic record
Abstract
Abstract The Yukon-Tanana terrane in the Finlayson Lake district, Yukon, represents one of the first arc–back-arc systems that formed adjacent to the Laurentian continental margin in the mid-Paleozoic. Back-arc rocks contain many large and high-grade volcanogenic massive sulfide (VMS) deposits. This study integrates U-Pb zircon geochronology, lithogeochemistry, and Hf-Nd isotopes to establish precise controls on tectonomagmatic activity adjacent to the western Laurentian margin in the Late Devonian to Early Mississippian. High-precision chemical abrasion- (CA-) ID-TIMS U-Pb zircon geochronology defines coeval arc (ca. 363.1 to 348 Ma) and back-arc (ca. 363.3 to 355.0 Ma) magmatism in the Finlayson Lake district that intruded continental crust of Laurentian affinity (e.g., Snowcap assemblage). Mafic and felsic rocks display geochemical and isotopic characteristics that are consistent with being formed from mixtures of depleted asthenosphere and enriched lithospheric mantle sources. These melts variably entrained Laurentian continental crust via high-temperature crustal melting due to basaltic underplating. The high-temperature back-arc felsic magmatism occurs at specific time periods coinciding with VMS deposits and supports previous genetic models for VMS mineralization that suggest elevated heat flow and hydrothermal circulation were due to regional-scale rift-related magmatism rather than from local subvolcanic intrusions. The short timescales and transient nature of tectonomagmatic events in the Finlayson Lake district suggest that rapid and complex subduction initiation of oceanic and continental crust fragments facilitated coeval compression, extension, and magmatism in the arc and back-arc regions. We thus reevaluate the presently accepted tectonostratigraphic framework of the Finlayson Lake district and suggest revised interpretations that shed light on VMS depositional environments and a possible broader association with the ca. 358 Ma Antler Orogeny. Results of this study have implications for incipient tectonics, magmatism, and mineralization along the western Laurentian continental margin and other orogenic belts globally.
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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 | 0.000 |
| 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 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".