Transpression or polyphase deformation along craton margins: Insights from the Archean–Proterozoic boundary near Sudbury, Canada
Bibliographic record
Abstract
Continental margins vary in composition and configuration, resulting in complex structural geometries during deformation. One example is the Archean-Proterozoic boundary near Sudbury, Canada, where the Creighton-Victoria Deformation Zone (CVDZ) contains both reverse dip-slip and dextral strike-slip kinematic indicators. To resolve if these structures formed during a single transpression event or multiple overprinting events, the orientation, relative timing and style of the CVDZ are compared to those of adjacent regional structures. Regional fold axes and their axial planar foliation are subparallel to the steeply-plunging stretching lineation and steeply-dipping foliation, respectively, along the CVDZ. Phase equilibria modelling of syn-tectonic staurolite-chloritoid assemblages indicates that the regional folds and foliation formed at 480–565 °C, similar to temperatures estimated for the formation of dip-slip quartz crystallographic preferred orientations (CPO) along the CVDZ. This suggests that the CVDZ, regional folds and foliation formed during the same regional folding and reverse shearing event. Major lateral lithological changes and inflections in the orientation of the craton margin controlled the formation of structures, and evidence for regional transpression, such as strike-slip kinematic indicators, steeply-plunging stretching lineation, and obliquity of regional folds with respect to major shear zones, resulted from polyphase deformation and transcurrent reactivation of the Superior craton margin.
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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 | 0.002 | 0.004 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".