Iron oxides in fractured quartz – development and evolution of iron sandstone layers in the Kinshasa area, DR Congo
Bibliographic record
Abstract
Quartz grains in an iron sandstone layer in near-surface sandy deposits at Kasangulu, south of Kinshasa, DR Congo, are marked by the presence of iron oxides in subparallel horizontal cracks within the sand grains. This exceptional feature was investigated to understand its origin and paleoenvironmental significance. Based on thin section observations, supplemented by Mössbauer spectroscopy results and other data, the occurrence of filled subparallel cracks is attributed to iron oxide remobilisation following crack opening within an iron-oxide-cemented sand intercalation that became exposed through erosion, whereby crack opening is related to surface temperature fluctuations. The development of filled crack occurrences of this type requires a period of surface exposure, implying that their presence is indicative of the position of former surface levels. A macroscopically similar iron sandstone layer at another locality in the Kinshasa area, lacking filled cracks, provides indications for both surface exposure and cement type as factors in their development.
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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) | 0.001 | 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".