Bibliographic record
Abstract
Abstract Abundances of rare earth elements (REE), Sc, Co, Hf, Ta and Th have been determined by neutron activation analysis in kimberlites from the Wesselton pipe, in micaceous kimberlites from the Swartruggens fissure and kimberlite from the Monastery Mine, Ison Creek and Somerset Island pipes. Kimberlites are characterized by a high REE content and have chondrite normalized REE distribution patterns which show extreme fractionation of the REE group, e.g. kimberlite La Yb = 100 ; micaceous kimberlite La Yb = 140 . Distribution patterns are linear, with weak negative Eu anomalies evident in the micaceous types. It is considered that the major sites of REE are apatite, perovskite and carbonate and that Eu anomalies are due to the presence of perovskite or mica. REE distributions are analysed in terms of partial melting and eclogite crystallization models by means of REE crystal-liquid distribution coefficients. Partial melting models indicate that the La Yb ratios of kimberlites and micaceous kimberlites can be produced independently by differing amounts of partial melting ( La Yb ratio (ca. 5) which was produced by extensive (15–20%) partial melting of garnet lherzolite mantle. REE distributions do not provide evidence in favour of any one petrogenetic model, especially with regard to La and Yb abundances; this is considered to be a reflection of errors in the magnitude of the distribution coefficients. Evidence bearing on the possibility of eclogite crystallization from kimberlitic magmas is reviewed (i.e. eclogite distribution, age, mineralogy of kimberlite and of inclusions in diamonds) and is interpreted to indicate that eclogite fractionation is the least likely means of generating kimberlite liquids. The relation of kimberlite magmatism to continental basaltic magmatism is considered in terms of a partial melting model in which the extent of partial melting of the mantle is dependent upon heat flow variations with time. The small volumes of liquid required in partial melting hypotheses are thought to be concentrated into kimberlitic magmas by shearing processes.
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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 | 0.000 |
| 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".