Paleoenvironmental and diagenetic effects on porphyrin distributions in the End-Devonian Exshaw Formation, Western Canada
Bibliographic record
Abstract
Porphyrin distributions were studied across 20 locations in the Western Canada Sedimentary Basin, particularly focusing on sediments deposited at the base of the Exshaw Shale, spanning the Devonian-Carboniferous boundary and contemporaneous with the Hangenberg mass extinction. Locations along a north–south transect represent thermally immature kerogen, while locations from east to west show a gradient of increasing thermal maturity. The study aimed to identify regional variability in syn -depositional environmental conditions and post-burial diagenesis influencing porphyrin preservation along the two transects. The relative abundance of three major categories of vanadyl porphyrins – cycloalkanoporphyrins, bicycloalkanoporphyrins, and etioporphyrins from the different sites exhibit notable spatial diversity, with the primary factor affecting their distribution being thermal maturity. Effects of paleoredox conditions and degree of organic matter decomposition were evaluated using trace element enrichments, thermal Rock Eval data, sterane and homohopane maturity indices.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".