Formation of the Rustenburg Layered Suite by assimilation – batch crystallization (ABC) and – fractional crystallization (AFC)
Bibliographic record
Abstract
Abstract The Rustenburg Layered Suite (RLS) of the Bushveld Complex of South Africa is a vast layered accumulation of mafic and ultramafic rocks. The layers are widely assumed to result from fractional crystallization from a melt-dominated magma chamber. We derive compositions of all units of the RLS with thermodynamic models of assimilation of crust by a komatiitic parent magma. Ultramafic U-type cumulate layers represent crystal mush produced by single stages of assimilation-batch crystallization (ABC). Anorthositic (A-type) magma mushes emerged by a second stage of batch crystallization during ascent of melts supernatant to mid-crustal U-type cumulates. Only the ferrobasaltic magma of the Upper and Upper Main Zone formed via classical assimilation-fractional crystallization (AFC) and ponded in a melt-dominated magma chamber that subsequently evolved by fractional crystallization. Mineral deposits associated with reversals between mafic and ultramafic layers, hitherto attributed to magma chamber processes, might form in small intrusions entirely lacking melt-dominated magma chambers.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".