Palustrine Deposits on a Late Devonian Coastal Plain—Sedimentary Attributes and Implications for Concepts of Carbonate Sequence Stratigraphy
Bibliographic record
Abstract
Abstract Palustrine deposits in coastal environments can cover thousands of square kilometers and are stratigraphically important. Palustrine deposits that originated in supratidal marshes can be used to track shifts in the shoreline position, whereas palustrine deposits that formed in marshes above the peritidal realm are indicative of subaerial unconformities. Despite the importance of these deposits, there are few documented examples of ancient coastal palustrine deposits, and their sedimentary attributes remain poorly understood. Misinterpretation of coastal palustrine deposits as marine deposits, or calcrete, may partly explain this situation. The Upper Devonian Alexandra Formation, exposed in the Northwest Territories of Canada, is formed of two reef complexes that are separated by a Type I sequence boundary. At the landward part of the platform, this boundary is marked by a succession of coastal-plain deposits that is ~ 50 cm thick. The most distinct aspect of this succession are palustrine deposits characterized by charophytes, skeletal (Rivularia) stromatolites, and various pedogenic features including complex crack networks, root traces, and authigenic kaolinite. Karst features and calcrete, generally regarded as typical indicators of subaerial exposure, are not found. This study highlights the sedimentary attributes that can be used to identify ancient palustrine deposits in marine coastal regions, distinguish these deposits from calcrete, and demonstrates their sequence stratigraphic significance, when found in marine limestone successions. It clearly demonstrates that palustrine deposits, like those found in the Alexandra Formation, should be considered indicative of subaerial unconformities and sequence boundaries, in the same manner as karst and calcrete.
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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 | 0.001 | 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 | 0.000 | 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".