An outcrop evidence for polycyclic orogenies in the basement complex of Southwestern Nigeria
Bibliographic record
Abstract
In this work, the tectonic history of a classic outcrop of the Migmatized-Gneiss Complex of Southwestern Nigeria was systematically investigated. The aim of this research is to investigate how the polycyclic nature of the basement complex in Southwestern Nigeria is preserved at a local or outcrop scale. Detailed geological mapping of the outcrop was done using ‘bit-a-bit’ technique in four pre-defined quadrants. Structural measurements include a detailed inventory of fold geometry, attitudes of veins, joints, and boudins. The outcrop is characterized by alternating leucosomes and melanosomes, fractures, S-C fabric and microfolds. Three metamorphic events were interpreted in the outcrop M1, M2 and M3, which are linked to deformation D1 to D3. These events suggest that the outcrop evolved through a complex interplay of compression, extension, and late stage sinistral movement. Phase I extension is coincident with the emplacement of veins, which were later compressed into ptygmatic folds. These veins were intersected by joints associated with Phase II deformation. During the third episode of extension, quartzo-feldspathic veins were emplaced normal to the orientation of earlier joint sets. The N-S, NE-SW and NW-SE trends of the structures are consistent with the polycyclic fabric of the Nigerian basement complex. This work has shown that macroscopic structures in the study area present unique evidence for the regional polycyclic history of the bedrock in Southwestern Nigeria.
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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 | 0.000 |
| 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".