Illitization and chloritization of illitesmectite and chloritesmectite mixed-layer clays in high-grade diagenetic and very low-grade metamorphic environments of Gaspe Peninsula, Quebec Appalachians, Canada : problems and solutions
Bibliographic record
Abstract
The present study deals with three main mineralogical and geochemical problems related to the behaviour of two common clay minerals---illite and chlorite---in the Lower Paleozoic sedimentary sequences of high-grade diagenetic and very low grade metamorphic (VLGM) zones in the Quebec Appalachians, Gaspe Peninsula. In high-grade diagenetic to VLGM zones, illite and chlorite coexist, but as they are notoriously fine-grained and intimately intergrown, tracing the chemical changes in chlorite with conventional (wet chemical method or electron microprobe) methods is a difficult task. A refined XRD method for the determination of the structural formula of chlorites was developed in this study. Application of this program to high-grade diagenetic to VLGM chlorite from the Gaspe Peninsula revealed that these chlorites are of "ripidolitic" to "pycnochloritic" composition and show a compositional homogenization in the anchizone, as compared to chlorite of the diagenetic zone. With increasing metamorphic grade, chlorites become less siliceous, have decreasing octahedral-site vacancies, and approach the ideal trioctahedral chlorite composition. Although Fe-asymmetry increases, the [Fe (total)] decreases, which may reflect a preferential decrease in [Fe (total)] in the brucite-like sheet. At high (>80%) illite levels in mixed-layer illite smectite, the gradual improvement of illite crystallinity (IC), coupled with advancing VLGM conditions, suggests some modification of the clay mineral structure, possibly involving loss of the still existing expandable layers. Failure to detect expandable components in anchimetamorphic illitic materials upon glycolation has led previous investigators to rule out the existence of expandable components beyond the high-grade diagenetic zone. X-ray diffraction (XRD) patterns and high-resolution transmission electron images of n-alkylammonium-cation-treated clay minerals showed the presence of expandable layers in high-grade diagenetic to VLGM phyllosilicates and document the impact of these expandable layers on IC measurements. With advancing diagenetic to VLGM grade, the intermediate metastable phases of a rectorite-like R1-ordered layer structure, either with an intermediate or high-charge vermiculite interface, and an R3-ordered structure are found in the fine fraction. (Abstract shortened by UMI.)
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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".