Fluvial to Estuarine Valley-Fill Models Without Age-Equivalent Sandy Shoreline Deposits, Based on the Clearwater Formation (Cretaceous) at Cold Lake, Alberta, Canada
Bibliographic record
Abstract
Abstract A commonly assumed element of sequence stratigraphic theory is that incised valleys must feed lowstand deltas. This model persists despite examples in which no lowstand deposit is present at the distal ends of some ancient and recent valley fills. The Clearwater Formation at Cold Lake Field, Alberta, Canada, presents a unique opportunity to investigate in detail the transition from fluvial incised-valley fills to open marine mudstone using over 1000 wells, over 400 with core, from an area of 3,200 km2. The presence of prominent marine well-log markers and the abundance and density of well logs allows confident correlation of the incised-valley fills. The Clearwater Formation consists of 13 stacked incised valleys with depths of incision ranging from 30 m to possibly 120 m. All of the valley fills show a depositional facies pattern from sandy fluvial or upper estuarine updip to muddy estuarine or marine deposits downdip. All of the valleys terminate downdip as thin (< 2 m) sheets of marine sandy mudstone. Significantly, none of the valleys are connected to downdip lowstand deltas, or even sandy lowstand shorelines. In addition, the valley-fill lithofacies differ significantly from the marine strata into which they are incised; they are sandier, and the sand fraction is coarser. The valley fills, therefore, are not composed only of reworked material eroded from valley walls, but represent sediment delivered from more proximal sources, presumably by rivers. Our examples demonstrate that the presence of deep incised valleys, even if they are filled with coarse material, cannot by itself be used to predict sand delivery to the paleo-shoreline or more basinward regions. We recognize two primary conditions for valley fills that lack associated sandy lowstand deposits: the lowest point of relative sea level was above the continental shelf edge (for passive-margin settings), and sediment delivery during early rising sea level was limited. For the examples cited we interpret that filling of incised valleys occurs during relative sea-level rise when only limited amounts of sediment can be delivered beyond incised-valley mouths.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
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".