Chapter 4. Evidence of working petroleum play systems: oil seeps and slicks
Bibliographic record
Abstract
Maturation and accumulation of economic quantities of hydrocarbons are a common sedimentary component of continental rift basins around the world, both ancient and modern. Thus, groundwater is not the only fluid that may migrate along major rift faults away from basinal depocentres. De-risking petroleum exploration in rift basins requires demonstrating the presence of working petroleum play systems, and the presence of leaking hydrocarbons to the surface is a primary way of demonstrating they are operating. Oil seeps have been known in Lake Albert since 1925 and the Kingfisher, Mputa–Waraga and Jobi–Rii petroleum play systems are due to go into full oil production. Lake Edward, however, has remained a virgin frontier exploration area. Tufa–travertine limestones along the eastern rift-bounding fault of the Rwenzori Mountains have yielded organic residues which gas chromatography–mass spectrometry analyses indicate have a mature, oil-like distribution. Biomarkers suggest a marine shale source rock, the origin of which is at odds with both oils from Lake Albert and generation within the present East African Rift System. A Lake Edward Slick Survey also sampled oil on the water surface that has the same biomarker signatures as the tufa–travertine-derived residues. Together they suggest maturation from a deeper pre-Neogene (?Mesozoic–Paleogene) rift sequence.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.017 | 0.002 |
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".