Facies-selective porosity in the Silurian (Wenlock) Lockport Group dolostone succession (Elora, Ontario): improving characterization of formation-level porosity
Bibliographic record
Abstract
ABSTRACT This study improves porosity conceptualization in the Silurian (Wenlock) dolomitic Lockport Group using core-scale analysis of relationships between depositional facies and the distribution of macroporosity. This dolostone succession forms a crucial regional aquifer, and its shallowly buried to outcropping strata in the study region of Elora (Ontario, Canada) correlate with more deeply buried (> 400 m) petroliferous strata in the flanking Michigan and Appalachian basins. Periods of deposition recorded in the local Lockport Group lithofacies succession were influenced by eustasy and paleo-forebulge movement. Initial deposition established variably thick crinoid–tabulate coral shoals in rising accommodation space over a beveled paleosurface. Thickest shoals (∼ 30 m) are succeeded by tabulate coral mud mounds with stromatactis whereas thin shoals (∼ 15 m) are overlain by argillaceous cherty dolomudstone. Difference in water depth was eliminated through accumulation of subtidal dolomudstone between mounds while stromatoporoid-dominated buildups formed on mound tops. Continued shallowing resulted in regionally extensive fossiliferous peritidal facies. Inter-basin correlation suggests that shallowing in the Lockport succession was coeval with migration of mud mounds into the Michigan Basin and deepening in the Appalachian Basin. In the Lockport succession, about 40% of porosity is fabric-selective, represented by primary (fenestral, intraparticle) and early secondary (moldic) porosity. Fabric-selective porosity favors those facies dominated by tabulate coral, bivalves, and gastropods. An additional ∼ 10% of total porosity is non-fabric-selective (e.g., fractures, vugs, channels) yet exhibits a clear facies influence: solution-enhanced fractures bounding thin crinoid dolorudstone beds and channels developed along some facies boundaries. Remaining porosity is non-fabric-selective and exhibits a more subtle facies influence. This study demonstrates the importance of considering the influence of specific facies on porosity in formation-level hydrogeological analysis.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".