High-resolution stratigraphy of the deep-water lower Cloridorme Formation (Ordovician), Gaspé Peninsula, based on K-bentonite and megaturbidite correlations
Bibliographic record
Abstract
The Ordovician Cloridorme Formation is a thick foreland-basin turbidite succession that for several decades has served as a natural laboratory for the long-distance physical tracing and study of single turbidites. A robust temporal correlation of these deposits is a prerequisite for the evaluation of sedimentary processes. Published stratigraphic subdivisions of the lower part of the Cloridorme Formation have impeded rather than facilitated such studies because of errors in the physical correlation of contemporaneous deposits. Tracing of the deposits of exceptionally large gravity flows, known as "megaturbidites," was previously recognized as a useful stratigraphic tool. Here, we strengthen and revise the stratigraphic framework based on megaturbidites by considering nine widely traceable and geochemically fingerprinted tuffs (K-bentonites). Two discriminant functions incorporating the abundances of six trace elements (V, Sm, Nd, Th, Er, Zr) permit the unambiguous distinction of the lower four tuffs. The other tuffs can be successfully distinguished using bivariate plots of TiO2, Th, Sc, and Eu. The tracing and correlation of 71 megaturbidites and the nine K-bentonites permits a high-resolution subdivision of the lower Cloridorme Formation. Particularly thick megaturbidites mark the boundaries of three newly defined allostratigraphic members (St-Hélier Allomember, St-Yvon Allomember, and Petite-Vallée Allomember). This precise temporal framework shows that the stratigraphic heights of the contacts of lithostratigraphic members defined by other workers in 1969 and 1991 were miscorrelated by more than 400 m over short lateral distances!
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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".