Provenance and depositional environment of organic-rich calcareous black shale of the Late Ordovician Macasty Formation, western Anticosti Basin, eastern Canada
Bibliographic record
Abstract
The organic-rich Macasty shale in the Gulf of St. Lawrence was deposited in the Late Ordovician during the Taconic orogeny. The orogeny involved explosive volcanism and thrusting of allochthonous rocks in the eastern margin of North America. Neodymium isotope compositions of the shale show that the provenance is predominantly Grenvillian granite–gneissic rocks, which were widely exposed north of the basin, with little contribution from Taconic igneous rocks. The bulk composition and the presence of detrital kaolinite suggest that the Grenvillian source rocks underwent intense weathering before erosion. Fine-grained detritus was deposited in the Anticosti Basin, where abundant organic activity kept the sediment–water interface under anoxic conditions. This proposed interpretation is supported by the enrichment of redox-sensitive elements, such as As, V, and U, and by high δ 34 S for pyrite. Calcite cement formed in the pore space of sediments during the diagenesis at temperatures below 60 °C. The low-temperature diagenetic conditions are consistent with the preservation of abundant organic matter in the shale.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".