Influence of channelized-flow density structure on the stratal architecture of deep-marine levee deposits
Bibliographic record
Abstract
ABSTRACT Deep-water channel and levee deposits are common depositional elements on modern and ancient continental slopes. Unlike their channel counterparts, the spatial and temporal evolution of levee stratigraphy is much less well understood, in part because of the typically more recessive nature of levee deposits in the ancient sedimentary record, and sparse, widely spaced core control or seismic images of insufficient resolution in the modern. Moreover, it is generally inferred that levee development, at least in part, precedes the main phase of channel filling, the reasons for which remain largely unknown. In the Isaac Formation of the Windermere Supergroup (Neoproterozoic) of east-central British Columbia, Canada, well-exposed levee deposits are divided vertically into packages, each consisting of a sand-rich lower part overlain sharply by a mud-rich upper part. The lower part (3–10 m thick) consists mostly of medium- to thick-bedded, upper medium- to coarse-grained, lower-division turbidites intercalated with thin-bedded, fine-grained, upper-division turbidites. Along depositional strike away from channel-fill margins, the thickness of lower-division turbidites exhibit a distinctive thickening and then thinning over a few hundreds of meters that results in a similar thickening and thinning of the entire lower part of a package. The upper part (3–16 m thick) consists mostly of thin-bedded, fine-grained, upper-division turbidites intercalated with uncommon medium- to thick-bedded, medium-grained, lower-division turbidites. Significantly, the thickness of very thin- and thin-bedded turbidites in the upper part generally decreases stratigraphically upward whereas the thickness of intercalated medium- and thick-bedded turbidites changes little. The lateral and vertical changes in these deposits suggest that channelized flows were initially coarse grained and moderately well-sorted, causing them to exhibit negligible density stratification, and therefore high flow efficiency. We interpret that the velocity maximum occurred above the height of the incipient channel margins, thereby allowing the lower, coarse-grained, dense part of flows to easily overspill and deposit thick-bedded, coarse-grained turbidites in the lower part of each package. The sharp contact with the upper part of each package marks the point when relief from channel floor to levee crest exceeded the height of the velocity maximum in average throughgoing turbidity currents. Above this height, density of the flow decreased abruptly and consisted of significantly finer-grained sediment that overspilled to form the upper, finer-grained part of each package. Later the makeup of the sediment supply changed to a more polydispersed grain-size distribution, which caused the throughgoing currents to be more density stratified. This enhanced near-bed stratification and concentration effects, which in addition to intense interfacial mixing, resulted in rapid kinetic energy loss, and promoted deposition in the channel.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".