Buckle folding and deep-crustal shearing of high-grade gneisses at the junction of two major high-strain zones, Central Gneiss Belt, Grenville Province, Ontario
Bibliographic record
Abstract
Low-plunging, transport-parallel F3 folds are common at all scales in the Central Gneiss Belt of the Grenville Province, but few of these folds are sheath folds. Where the D1D2 Parry Sound shear zone intersects the D3 Shawanaga shear zone (SSZ) at a high angle, F3 folds formed at several scales (centimetre to greater than outcrop scale) in layered D1D2 "straight" gneisses. At the start of their evolution, the F3 folds formed just beyond the SSZ with hinges near orthogonal to the D3 shear direction and with typical buckle features, e.g., wavelengths vary with layer thickness, and hinges are discontinuous and bifurcate. The buckle folds evolved within the SSZ by rotation of hinges towards the shear direction. Even though hinges initiated at a high angle to the shear direction, sheath folds were not produced. In addition to tightening the buckles, the ductile reorientation produced thinthick (extendedshortened) limb pairs and very straight, ridge-like fold hinges and removed small folds from the extended limbs of larger folds. Such features may serve as criteria to distinguish transport-parallel folds that initiated in layering at high angles to the shear direction from those formed in layers containing the shear direction. A general shear parallel to the SSZ can reproduce several features inferred to mark stages in the progressive reorientation of the folds; the pure shear component of the general shear is inferred to have had a positive stretch direction down the dip of the shear zone, at a high angle to the transport (simple shear) direction. The interplay of buckling and shearing in the study area is, plausibly, the expression of deformation at the upper boundary of a channel-like flow that succeeded initial crustal thickening.
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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 | 0.001 |
| 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".