Diagenetic alteration of magnetic minerals in Labrador Sea sediments (IODP Sites U1305, U1306, and U1307)
Bibliographic record
Abstract
In order to reveal the potential effects of early diagenesis on magnetic minerals in deep‐sea sediments, we studied early diagenetic zones and magnetic mineral characteristics of Lower Pliocene hemipelagic sediment samples from IODP Sites U1305, U1306, and U1307 on Eirik Drift, Labrador Sea. All samples analyzed were unlithified silty clay sediments recovered by a piston corer from depths down to 200 meters composite depth (mcd). Based on shipboard interstitial‐water geochemistry, we divided the sediment column from each site into six early diagenetic zones. Magnetite (Fe 3 O 4 ) was present at all analyzed depths, whereas maghemite ( γ Fe 2 O 3 ) was found only above the iron reduction zone. We attribute this to associated changes in interstitial redox conditions, which induced preferential dissolution of maghemitized surfaces on magnetite grains. Mineral magnetic results indicate a general down‐hole change in mean grain size of magnetic minerals. At Site U1307, which has relatively low organic carbon contents, the diagenetic zones occur at greater depths than at the other studies sites. This suggests that interstitial oxygen levels at this site remained high enough to degrade organic matter through oxic bacterial activity, and that detrital magnetic minerals have been preserved even at depth.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".