Tempestite frequency curves: a key to Late Ordovician and Early Silurian subsidence, sea-level change, and orbital forcing in the Anticosti foreland basin, Quebec, Canada
Bibliographic record
Abstract
Following partial closure of the northern Iapetus Ocean along the Newfoundland segment of the St. Lawrence Promontory, subsidence along the Anticosti Platform was influenced by residual thermal subsidence, renewed tectonic loading by thrust sheets to the south, and sediment loading. Basement subsidence, calculated by removing the effects of sediment loading, was between 2 and 5 cm/ka in the Caradocian, increasing to 8.6 cm/ka in the Pusgillian and Cautleyan, and reaching a maximum of 17.7 cm/ka in the Rawtheyan, during deposition of the Princeton Lake and Vauréal Formations. A marked decline in subsidence, beginning in the Hirnantian and continuing into the Early Silurian, may reflect decoupling of thrust loads to the south, although a further stage of thrust loading may have occurred in the Aeronian during deposition of the lower part of the Jupiter Formation. Storm frequency curves, produced using tempestite abundance, thickness, and grain size through more than a kilometre of carbonate strata on Anticosti Island, allow recognition of long period, 3rd-order trends. These are in part similar to local sea-level trends deduced from direct interpretation of sedimentary structures, but depart significantly from paleontological-based sea-level curves. Shorter period 4th-order cycles appear to be related to orbital eccentricity with periods of 100 and 400 ka. These may reflect periods with falling sea levels, increasing storm activity, or enhanced sediment flux to the middle and outer shelf.
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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 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".