Tectonostratigraphic framework of Upper Ordovician source rocks, Ottawa Embayment (eastern Ontario)
Bibliographic record
Abstract
Abstract Two intervals of Upper Ordovician organic-rich (gas-prone) source rocks are preserved in a regional fault block of approximately 1000 km2 within the Ottawa Embayment (eastern Ontario). They bracket an apparent conformable mid-Katian (late Edenian to early Maysvillian) transition from a relatively shallow-water carbonate platform setting to a deep-water shale basin within the local Taconic foreland basin. The platform succession is represented by the Lindsay Formation, and records deepening and replacement of a once skeletal-rich, productive platform environment by fossiliferous shale and limestone facies association (10 to 18 m thick) comprising the Eastview Member. Nodular and bedded crinoidal lime mudstone is intercalated with fossiliferous (trilobite, brachiopod) organic-rich (2–6% TOC) shale. The upper 2 m of the unit contain shale with dispersed to compacted accumulations of trilobites and brachiopods. The Eastview Member thickens to the southeast, and is overlain with apparent conformity by organic-rich (2–4+% TOC) shale of the Billings Formation. Regionally, this latter unit is approximately 20 m thick, and accumulated in an anoxic to dysoxic deep-water basin. Thin laminae of siltstone to fine-sandstone herald the later, principal, phase of basin fill by sandstone and shale that characterize the overlying Carlsbad Formation. Geophysical (gamma-ray) transects restricted to the western embayment reveal km-scale spacing of high-angle faults and small-scale synsedimentary horsts and grabens that formed after shallow (3–5 m) burial of the Eastview Member. One small-scale graben illustrates a near doubling (<40 m) of the Billings Formation. A tectonostratigraphic framework for source rock accumulation includes a first-order geodynamic control driving regional platform foundering, then a higher-order structural response that enhanced local thickness of organic shale and created faults subject to reactivation in post-Ordovician time.
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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 | 0.004 | 0.004 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.008 | 0.001 |
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".