Changes in Depositional Processes—An Ingredient in a New Generation of Sequence-Stratigraphic Models
Bibliographic record
Abstract
Abstract Existing sequence-stratigraphic models for shoreline deposits commonly assume a constant process regime throughout the relative-sea-level (RSL) cycle over a wide range of timescales (third-order cycles as well as high-frequency, fourth- and fifth-order cycles), with the possible exception that tidal processes may be more important during transgressions. However, the dominant process affecting the coastal zone is a function of multiple interdependent factors and can change at any time during high- or low-frequency RSL cycles; indeed, changes are possible on timescales as short as 1,000 years. Thus, the relative intensity of wave and tidal processes may change gradually or abruptly on a regional scale because of changes in bathymetry or coastal morphology caused by rising or falling water levels, and/or changing shelf width. The specific nature of the response varies as a function of the physiographic and tectonic setting because the attenuation or amplification of wave and tidal action is strongly dependent on local and regional bathymetry and coastal morphology. Fluvial energy may also vary with sea-level change, as a result of climate change. Moreover, whereas most facies and sequence-stratigraphic reconstructions are based on river-, wave- or tide-dominated end-member environmental models, the majority of real-world environments are of mixed-energy character where these processes coexist in subequal proportions. In such mixed-energy coastal environments, changes in the relative intensity of the depositional processes on a local scale can also cause stratigraphic variations in the nature of the deposits as the environments migrate laterally. Reconstructions of regional or local process changes are complicated by the fact that changes in the grain size delivered to the coast, as a result of systematic variations in fluvial accommodation and the degree of bypass, may cause product changes without any change in the processes. Fine and very fine sand, such as is dominantly delivered to the transgressive and highstand coastlines favors the preservation of wave-generated hummocky and swaly cross stratification, whereas medium and coarse sand, as is delivered to the falling stage and early lowstand coastlines, permits the development of current-generated (including tide-driven) cross stratification. Future sequence-stratigraphic models need to incorporate and be more sensitive to such process and product changes.
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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 | 0.002 | 0.006 |
| 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 | 0.002 |
| Scholarly communication | 0.003 | 0.004 |
| Open science | 0.004 | 0.002 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.004 | 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".