Paleozoic evolution of the northern Laurentian margin: Evaluating links between the Caledonian, Ellesmerian, and Cordilleran orogens
Bibliographic record
Abstract
ABSTRACT The passive margins of Laurentia that formed during Neoproterozoic–Cambrian breakup of the supercontinent Rodinia record subsequent histories of contraction and translation. This contribution focuses on the northern margin of Laurentia, where recent geologic and geochronologic data have provided new insight into the evolution of northern North America. The Laurentian margin in East and North-East Greenland records synorogenic sedimentation and deformation associated with the Caledonian orogeny—the Silurian to Devonian continent-continent collision between Baltica and Laurentia that followed closure of the northern tract of the Iapetus Ocean. The timing of ultrahigh-pressure metamorphism and simultaneous sinistral and dextral strike-slip faulting in North-East Greenland indicates that the Himalayan-style orogen persisted through the Devonian. In contrast, the Franklinian margin further west records sinistral strike-slip translation of allochthonous crustal blocks and arc fragments starting in the Ordovician–Silurian and culminating with the Devonian–Carboniferous Ellesmerian orogeny, the origin of which remains enigmatic. We suggest that Ellesmerian deformation was related to widespread transpression associated with northward motion of Laurentia during Acadian and Neo-Acadian deformation along the Appalachian margin rather than orthogonal ocean basin closure and microcontinent-continent collision. The Pearya terrane and North Slope subterrane of the Arctic Alaska terrane, separated from the Franklinian passive margin by the Petersen Bay fault and Porcupine shear zone, respectively, best preserve the Paleozoic translational and transpressional history of the northern Laurentian margin. These two major structures record a complex history of terrane accretion and translation that defines the Canadian Arctic transform system, which truncated the Caledonian suture to the east and ultimately propagated early Paleozoic subduction to the Cordilleran margin of western Laurentia.
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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 | 0.001 |
| 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) | 0.002 | 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".