Recognizing the product of concave‐bank sedimentary processes in fluvial meander‐belt strata
Bibliographic record
Abstract
Abstract Downstream migration of point bars is an important process in meander belts. Inherent to downstream migration is sediment accumulation in concave channel banks, immediately adjacent to and downstream of convex point bars. Despite this, associated concave bank processes are often overlooked, with depositional products sparsely identified in the stratigraphic record. Counter‐point‐bar deposits are a type of concave‐bank deposit that have been positively identified in subsurface three‐dimensional seismic datasets, yet outcrop examples are not well‐constrained. This study characterizes and establishes recognition criteria of counter‐point‐bar deposits in outcrop using extensive exposure of Late‐Cretaceous meander‐belt deposits in eastern Alberta, Canada. Using a combination of traditional field‐based sedimentological analyses and three‐dimensional outcrop mapping with an Uncrewed Aerial Vehicle and Structure‐from‐Motion photogrammetry, point bar, counter‐point bar, and associated abandoned‐channel deposits, as well as adjacent floodplain deposits are identified. Bed‐scale characteristics of counter‐point‐bar deposits include interlaminated and interbedded siltstone and fine‐grained sandstone, abundant organic detritus, and evidence of deformation and slumping. At the bend scale, accretion packages bounded by internal erosion surfaces are composed of dipping siltstone and minor sandstone beds that extend from the top to the base of the meander belt. At the belt scale, positive identification relies on concave accretion surface mapping, their orientation relative to the meander‐belt edge (i.e. dipping away), and consideration of meander‐bend evolution. These results have implications for recognition of counter‐point‐bar deposits in analogous, less‐constrained data sets, which provides a foundation for more complete palaeoenvironmental interpretations.
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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 | 0.000 | 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) | 0.002 | 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".