Molar-Tooth Carbonates: Shallow Subtidal Facies of the Mid- to Late Proterozoic: Discussion
Bibliographic record
Abstract
From field work in northern Canada and many other examples documented in the literature, James et al. (1998) highlighted the potential use of molar-tooth structures (i.e., a series of spar-filled cracks) as a stratigraphic indicator for the Mesoproterozoic and Neoproterozoic. These authors also stated that all known occurrences where molar-tooth structures are volumetrically significant are from shallow-water carbonates. Although these are comprehensive statements, considering that most molar-tooth structures reported so far are from shallow-water Mesoproterozoic and Neoproterozoic deposits, I am concerned about such proposed temporal and environmental constrictions, which are not supported by the field data, summarized in the following. Detailed field work in the Grajau Basin, northern Brazil, revealed that structures similar to the ones reported by James et al. (1998) are volumetrically widespread in the Codo Formation. This is a lacustrine lithostratigraphic succession formed during the early stages of the South Atlantic rifting in the Aptian (e.g., Petri and Fulfaro 1983). The sedimentary features described here occur in lime mudstone to grainstone, ostracodal grainstone, and crystalline limestone interbedded with shales strongly affected by penecontemporaneous deformation, as indicated by a variety of complex convolute folds, small faults, fissures, and bed collapses. The molar-tooth structures occur throughout these beds, although they substantially increase in volume downward, where evidence for soft-sediment deformation diminishes. These …
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".