Lower Miocene Nukhul Formation, Gebel el Zeit, Egypt: Model for Structural Control on Early Synrift Strata and Reservoirs, Gulf of Suez
Bibliographic record
Abstract
Abstract The Aquitanian-early Burdigalian (lower Miocene) Nukhul Formation at Gebel el Zeit, Egypt, was deposited during early stages of Gulf of Suez rifting. The unit dips 8-15° less than underlying prerift strata, indicating that significant rotation and extension preceded subsidence of the Gebel el Zeit fault block. The Nukhul Formation at Gebel el Zeit is up to 75 m thick in outcrop and consists of a lower sandstone and an upper carbonate unit. The formation varies considerably along strike because of syndepositional differential movement of small fault-bounded blocks. The lower clastic unit at South Gebel el Zeit contains poorly sorted, conglomeratic, marly sandstone that commonly displays grading and Bouma sequences. Beds were deposited below storm base by sediment gravity flows. Thicker intervals are inferred to fill small, structurally controlled, submarine gullies that funneled sand and gravel southwestward to a half-graben basin. In contrast, an inferred correlative, thin, basal conglomeratic unit in North Gebel el Zeit was deposited in a shallow-marine setting. The presence of basement clasts in Nukhul strata indicates early syndepositional uplift due to structural tilting. The upper carbonate unit consists of bioclast, peloid, and intraclast packstone, wackestone, and grainstone with minor floatstone, rudstone, and coral-algal boundstone. Carbonate strata were deposited variously in deep-marine, low-energy peritidal and subtidal, and reefal environments. Deeper submerged blocks were the site of carbonate resedimentation or deeper shelf deposition. Reefs and shallow-marine bioclast shoals formed on higher submerged blocks. Nukhul strata show that synrift reservoir prediction in the Gulf of Suez, the Red Sea, and presumably in other rifts requires mapping of synrift cross faults and fault block by fault block facies analysis.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 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".