The Geshere syenite-peralkaline granite pluton: a key to understanding the anorogenic Nigerian Younger Granites and analogues elsewhere
Bibliographic record
Abstract
Periodico di Mineralogia (2011), 80, 1 (Special Issue), 199-215 - DOI: 10.2451/2011PM0016 Special Issue in memory of Sergio Lucchesi The Geshere syenite-peralkaline granite pluton: a key to understanding the anorogenic Nigerian Younger Granites and analogues elsewhere Shehu Suleiman Magaji 1 , Robert F. Martin 2,* , Echefu C. Ike 1 and Awajiokan E. Ikpokonte 1 1 Department of Geology, Ahmadu Bello University, Zaria, Kaduna State, Nigeria 2 Department of Earth and Planetary Sciences, McGill University, Montreal, Quebec H1A 1A7, Canada *Corresponding author: robert.martin@mcgill.ca Abstract The Geshere complex, one of the few intrusive centers among the Nigerian Younger Granites that has not yet been characterized, contains an association of syenite and peralkaline granite. The suite shows a classic sequence of rocks related by fractional crystallization of a parental magma, leading to the pseudoternary minimum in the granite system. The syenite is hypersolvus and contains a ferro-richteritic amphibole as the dominant femic mineral, whereas the most evolved granite is subsolvus and contains annite as the dominant femic mineral. Textural evidence points to the crystallization of these minerals from an interstitial femic melt present at the solidus of these rocks, in which magnesium is a trace constituent. Such a late melt appears because of the low thermal stability of these extremely Fe-enriched minerals and the massive removal of alkali feldspar. Calcite inclusions in the primary amphibole and annite, locally defining an emulsion texture, are considered to represent globules of a carbonate melt present at the source. Key words : syenite; peralkaline granite; anorogenic magmatism; Nigerian Younger Granites; ferro-richterite; annite; calcite globules; Geshere; 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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.005 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.005 | 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".