Architecture and Neogene kinematic of the Seagap fault, offshore Tanzania, West Somali Basin
Bibliographic record
Abstract
In the West Somali Basin, the classic plate tectonic reconstructions describe an early Cretaceous intraplate deformation of oceanic crust (Hauterivian to Aptian) followed by the activation of a major transform fault (Davie Fracture Zone) displacing Madagascar southward for more than 1000 km. In this contribution, using vintage and new high-resolution 2D, 3D seismic reflection data and exploration wells, we show the first clear images of a poorly known tectonic structure: the Seagap fault. The Seagap fault is represented by a complex fault zone of several hundred kilometres of extent, oriented parallel to the Davie Fracture Zone and defined by segment faults, relay zones and step overs structures. It appears to have continuously acted as left-lateral strike slip fault during the Paleogene and most of the Neogene. From structural and stratigraphic observations of both existing and newly interpreted 3D seismic data, the Seagap appears nucleating as a strike-slip fault by reactivating failed Jurassic oceanic spreading zones. At regional scale the main fault appears to cut the main Neogene pervasive extensional oblique rift structures and at place to re-work some of the major Cenozoic inherited structure, creating apparent restraining bend structure. The sinistral kinematic nature of the transcurrent history, suggests that the Seagap fault acted as an independent feature respect to the Davie Fracture Zone. During the Quaternary the Seagap, which also parallels the seismically active Kerimbas rift, shows reduced offsets and appears to slip with normal displacement. We discuss the tectonic significance of the Seagap fault with respect to both to the major extensional oblique rift structural trend offshore Tanzania and the Davie Fracture Zone.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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".