Schist Belts of the Benin‐Nigeria Shield Reveal a Neoproterozoic History
Bibliographic record
Abstract
ABSTRACT Belts of metasedimentary rocks (schist belts) in the Benin‐Nigeria Shield (BNS) are investigated for the first time using U–Pb dating and Lu‐Hf isotope analysis of detrital zircons. We report maximum depositional ages that place their deposition firmly in the Neoproterozoic and link them with strata in the Dahomey Belt, the central African fold belt, and the Borborema Province in South America. The detrital zircon age distribution also includes Archaean dates and is dominated by ~2.1 Ga zircons. The latter are derived from juvenile granitoids, likely forming much of the basement of the BNS. We bracket the detrital zircon data with U–Pb dates and Lu‐Hf isotope data of both the oldest (Kaduna Gneiss, 3571 ± 3 Ma) and youngest (Maradun Group rhyolite and related granitoids, 586 ± 2 Ma) Precambrian rocks of the BNS. By doing so, we highlight a 3‐billion‐year‐old record of crustal evolution in central Africa.
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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) | 0.002 | 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".