Organic petrography and thermal maturity of the Paskapoo Formation in the Fox Creek area, west-central Alberta
Bibliographic record
Abstract
The Paskapoo Formation, which ranges in age from middle to upper Paleocene, is the major shallow aquifer in Alberta. This study is part of a larger GSC-led study on the potential environmental impact of hydrocarbon development in the Fox Creek area (west-central Alberta) on shallow aquifers. Fox Creek is located near the northern limit of the Paskapoo Formation. In addition to the underlying organic-rich source rocks in the study area, including the Duvernay Formation that is currently exploited for hydrocarbon resources, the Paskapoo Formation contains organic-rich intervals and coal seams. In order to investigate any potential internal hydrocarbon sources within the Paskapoo Formation, ninety-seven (97) cutting samples from the formation obtained from eight shallow monitoring wells (50-90 m) in the study area were studied for total organic carbon (TOC) content, organic matter composition and thermal maturity of coal seams using programmed pyrolysis analysis and organic petrography. The TOC content of all samples ranges from 0.2 to 8.8 wt. %, with a mean value of 0.95 ± 1.6 wt. % (n=97). The Tmax values of studied samples range from 347 to 463 °C, with a mean value of 434 ± 20 °C that suggest a range of thermal maturity from immature to peak oil window. The random reflectance (Rr) measurement and fluorescence microscopy on eighteen (18) selected samples with TOC content > ~1 wt. % shows a mean Rr value of 0.27% and 0.42% for the overlying till deposits and the underlying shallow depth sandstone, siltstone, shale and coal seams respectively, indicating a low rank coal ranging from lignite to sub-bituminous coal. Blue to green and yellow fluorescing liptinite macerals further confirmed the low maturity of studied samples. The low S2 yield of a large part of the samples (65%) resulted in unreliable Tmax values that overestimated the thermal maturity. Although the organic matter in the studied intervals are immature, exsudatinite, as secondary liptinite maceral, was observed in samples from the lower parts of the studied monitoring wells. Exsudatinite generally derives from the transformation of sporinite, alginite, resinite and varieties of vitrinite, which is a resinous or asphalt like material. Considering the thickness and distribution of coal seams in the studied samples, it is unlikely the exsudatinite will be a major source for aquifer hydrocarbon contamination in the study area. Additional stratigraphic studies and molecular geochemical analysis could provide an estimate of the total volume of possible organic compounds contribution to the aquifer in the study area. Due to the presence of coal seams in the studied intervals of the Paskapoo Formation, it is important to investigate the possibility of biogenic methane formation in Paskapoo shallow aquifers.
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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 | 0.001 | 0.001 |
| 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".