S and Z buckle folds as shear-sense indicators in the ductile realm: Field examples from the Grenville Province of Ontario and the Appalachians of South Carolina
Bibliographic record
Abstract
To promote a wider use of S and Z buckle folds in field-based structural studies, we first formulate three conditions under which quasi-cylindrical segments of gentle to close S and Z folds indicate the sense of finite-shear components. Based on our results of shear-sense mapping, we then assess the validity of published geological hypotheses in well-exposed parts of the western Grenville Province and the Southern Appalachians. Near the Central metasedimentary belt boundary of southeastern Ontario, which is widely interpreted as a 1090–1050 Ma ductile thrust, most orogen-normal, southeasterly plunging, gentle to close folds in the main foliation prove to have S style. This attests to a regional component of orogen-parallel sinistral shear that probably postdates the ductile thrusting. In gneisses and schists of the northern Inner Piedmont, six deformation events (D1–D6) are recognized by other workers. We focus attention mainly on early Alleghanian, orogen-parallel folds (F3) and associated mineral-shape fabrics in the Salem-Sunset area, western Inner Piedmont of South Carolina. Here, the orientation and S and Z style of mesoscopic F3 features attest to an orogen-normal component of distributed thrust shear, and thereby strengthen the case for northwest-directed displacements of ductile thrust sheets during early stages of the Alleghanian orogeny.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.004 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".