Expandability of anchizonal illite and chlorite: Significance for crystallinity development in the transition from diagenesis to metamorphism
Bibliographic record
Abstract
In mixed-layer illite/smectite containing >80% illite, the presence of an expandable component and changes in its abundance are difficult or impossible to detect with the X-ray diffraction (XRD) method using conventional polar interstratification compounds, e.g., solvation with ethylene glycol. Although high-grade diagenetic and very low-grade metamorphic (VLGM) samples do not expand in response to ethylene glycol treatment, the illite crystallinity (IC) improves significantly with increasing diagenetic/metamorphic grade. Improvement of IC in anchizonal to epizonal samples previously was thought to be related primarily to increase in crystallite thickness and decrease in the number of stacking faults. The present study reexamines the contribution of expandable components to IC in shale and slate samples from the Gaspé Peninsula for both the <2 μm and <0.1 μm size fractions in the high-grade diagenetic and VLGM zone. As tools, we have used XRD patterns and high-resolution transmission electron microscopy (HRTEM) lattice-fringe images of samples treated with n-alkylammonium cations. These studies reveal the presence of expandable components including R1- and R3-ordered structures and "expandable illite." Expandable 2:1 clay minerals decrease in abundance with increasing metamorphic grade. The improvement of IC with grade is due to the decrease in expandable layers and also to the decrease in the number of lattice defects and an increase in crystallite size. Stacking faults may be the main source of lattice distortion only when phyllosilicates consist of thick non-expandable layer silicates.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| 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".