Authigenesis of Titania Minerals and the Mobility of Ti: New Evidence From Pro-Deltaic Sandstones, Cretaceous Scotian Basin, Canada
Bibliographic record
Abstract
Abstract: Titania (TiO2) minerals are minor diagenetic phases in many sandstone–shale successions, but the conditions of Ti mobility and titania authigenesis are poorly known. Here, new modes of occurrence of authigenic titania minerals, filling pores and replacing phytodetritus, are documented from Lower Cretaceous prodeltaic sandstones in the offshore Scotian Basin of southeastern Canada. Textural relationships suggest that titania minerals formed at the same time as kaolinite, most commonly below lowstand sequence boundaries, related to flux of meteoric water. Such authigenic titania is most abundant in thin-bedded sandstones interbedded with thick prodeltaic mudstone in which fine-grained detrital Ti-rich minerals are concentrated. Textures in titania that has replaced uncompacted phytodetritus suggest microbial mediation in near-surface eodiagenesis. Eogenetic titania is enriched in phosphorus (∼ 0.6% P2O5) and may co-occur with authigenic fluorapatite and crandallite crystals. Such titania resulted from prolonged flow of meteoric water that dissolved P from apatite and feldspar, thereby enhancing Ti solubility. In basins with supply of immature sediment from granitic terranes and important diagenesis by meteoric water, the assumption that Ti is an immobile element and that rutile or other titania minerals are exclusively of detrital origin may not be valid. Probable mesodiagenetic titania has low P content, suggesting that Ti mobility under these conditions was facilitated by some other agent, probably organic acids. The results of this study illustrate that even in cases where titania minerals are volumetrically insignificant, their microtextures and trace-element chemistry can provide important insights into the character of fluid flow during diagenesis of siliciclastic rocks.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| 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".