Mechanical Microdeformation and Kink–band Formation in Mica from the Colônia Impact Crater, São Paulo, Brazil
Bibliographic record
Abstract
A comprehensive examination using a transmitted light optical microscope was conducted to analyze the morphology and geometric parameters of kink band development in mica from the Colônia impact crater's crystalline basement rocks. Significant differences were observed between kink bands formed perpendicular and parallel to the [001] plane. Kink bands perpendicular to the [001] are narrow and elongated, exhibiting two distinct coplanar orientations with regular spacing and parallel planar fractures, which suggest a slip-dislocation strain mechanism. In contrast, kink bands parallel to the [001] plane exhibit a greater variety of shapes and a more complex internal structure. These kink bands can be grouped into six types: sigmoidal-shape, S-shape, lenticular-shape, Z-shape, Z-shape with internal dislocation, and Z-shape with internal rotation. The deformation patterns in these kink bands indicate two primary processes: flexural and shear strain. The most notable deformations induced by these strain mechanisms include the curvature of cleavage lamellae, delamination cracks, and fractures along the boundaries of kink bands. More severely deformed kink bands exhibit dislocation, rotation, and partial obliteration of internal cleavage lamellae. These characteristics differ from those of typical kink bands in tectonically deformed rocks, thereby reviving the longstanding debate regarding their potential use as alternative evidence in impact cratering investigations.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".