Sequence Stratigraphic Architecture and Evolution of Platform Margin to Basin Sedimentation
Bibliographic record
Abstract
Abstract Stratal stacking patterns and platform distribution within the Devonian Beaverhill Lake Sequence of northern Alberta were influenced by several factors, those that were primarily external (e.g., climate change, trade-wind flow, terrigenous mud supply) and those that were internal (e.g., carbonate factory, water circulation, basin topography). Within the first-rank Beaverhill Lake Sequence, our study revealed two second-rank (1,2) and 10 third-rank (A-J) transgressive-regressive (T-R) sequences within the Beaverhill Lake Sequence, many of which were progradational and basin-filling, even during a relative rise in sea level. Furthermore, our study reveals three distinct phases of sedimentation during the depositional interval. The first phase of sedimentation occurred during T-R sequence A. During the initial sea-level rise of sequence A, the Peace River Arch fringing platform and Hay River platform initiated along the western margin of the study area. Platforms aggraded, but they did not prograde significantly, likely because detrital carbonate sediment was transported by surface currents into the inner platform and because of the proximity of the platforms to a limited but adequate supply of nutrients. The condensed limestone across the shallow Waterways Subbasin at the end of sequence A was produced by a local carbonate factory within or near the base of the photic zone, but under nutrient-starved conditions. Slope environments near the platforms contained a mixture of locally produced carbonate sediment and transported allochems. Therefore, this first phase of sedimentation during the Beaverhill Lake Sequence contains circulation-and nutrient-constrained carbonate platforms on the western side of the study area and limited carbonate accumulation within a shallow basin. Mixing of sediments between the two environments occurred only within slope deposits. The second phase of sedimentation occurred during the clinoformal infilling of the Waterways Subbasin with the progradation of the carbonate-siliciclastic Eastern Platform, the drowning and burial of the Hay River platform, and the back stepping of the Peace River Arch fringing platform. Lithofacies and faunas found on the Eastern Platform generally grade into deeper-water components, often by the increase in argillaceous sediment in carbonate beds and the loss of shallow-water organisms. Basinal sediments are mainly argillaceous in the thin toes of the clinoforms in the Waterways Subbasin. Evidence of sediment transport by gravity flow or other mechanisms from the Eastern Platform down the slope and into the basin is rare in core and restricted to occasional tempestite-like beds and individual allochems derived from shallow-water organisms. Although the transport of micrite basinward by water currents is likely to have occurred, an in situ fauna inhabited at least the upper portion of the slope environment and produced carbonate sediment. The third and final phase of sedimentation in the Beaverhill Lake Sequence was generally aggradational, with a much-reduced difference in topography between the Eastern Platform and the Waterways Subbasin. Lithofacies and faunas found on the Eastern Platform can be traced into the Waterways Subbasin. Faunas change little, but lithofacies tend to become more argillaceous throughout the study area. The definition of the Eastern Platform margin can only be seen in cross section where carbonates thin abruptly westward.
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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) | 0.001 | 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 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".