High-resolution magnetic susceptibility as a proxy for sediment provenance change: age constraints on the Middle-Upper Eocene Atlasic event (central Tunisia)
Bibliographic record
Abstract
Abstract Magnetic susceptibility (MS) and clay mineralogy data from the Bougobrine and Souar sections (Middle-Upper Eocene) in central Tunisia are compared to known sedimentological and geodynamic data to highlight the timing of the Paleogene sediment source change. Previous works placed the Alpine compression event and the folding in central Tunisia at the Middle-Upper Eocene transition, followed by a shift in the sediment source at the Eocene-Oligocene boundary. Here, we show that the primary origin of sediments followed the tectonic events, leading to a significant change in the magnetic signal and clay mineralogy since the topmost Bartonian in the proximal section and the base of the Priabonian in the distal section. The hematite, goethite, and magnetite concentrations determine the variations in the magnetic susceptibility signal of the distal homogenous shales (Souar section). The shallow carbonate Bougobrine section exhibits less pronounced cyclicity due to diagenesis, high dilution by carbonate, and scarce magnetic minerals (washed towards the distal shales). Adverse cyclostratigraphic findings in the distal section indicate that multiple sediment sources during the Middle Eocene led to the absence of preserved magnetic susceptibility cyclicity. Our results indicate multiple source regions of the Lutetian-Bartonian deposits from the emerged northern, eastern, and SE provinces and a more dominant eastern origin from the Early Priabonian with a minor contribution from the north and eastern regions. Large rivers occurred during the Eocene-Oligocene transition, bringing siliciclastic deposits from SW Tunisia in line with previously hypothesized provenance patterns.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".