How many turbidity currents pass through a submarine channel during its lifespan?
Bibliographic record
Abstract
ABSTRACT Sediment gravity flows coursing through submarine channels are the most important conveyors of sediment and organic carbon to submarine fans. Submarine channel deposits, therefore, should record the archive of this sediment transfer. However, channel deposits have often been considered to be dominated by erosion and bypass, and thus an incomplete archive. We present data from a millimeter-scale investigation of an outcropping submarine channel element in the Cretaceous Tres Pasos Formation, southern Chile, that indicates that at least 520 sediment-gravity-flow events passed through a single channel during its lifespan. These 520 events are confined by one primary channel-form surface and 11 secondary channel-form surfaces that define the channel architecture. Three facies (axis, margin, drape) compose this architecture, with thick, coarser-grained, amalgamated event beds deposited in the axis, usually separated across secondary channel-form surfaces with thinner, finer-grained, non-amalgamated event beds deposited in the margin. The drape facies usually overlies secondary channel-form surfaces, and we interpret its presence as an indication of significant sediment bypass through the channel. The 520 events are mostly preserved in the channel margin (82%), but the volumetric composition of the channel element is dominated by axis deposits (58%), with margin (37%) and drape (5%) being less significant. This indicates that the axis deposits, while the focus of many channel-related studies, record only a fraction of the temporal evolution of the channel. The channel margin, on the other hand, is the archive of turbidity-current activity in the channel. Using reasonable event recurrence intervals and turbidity-current-event sediment volumes, we estimate that the studied channel was active for approximately 5,000 years with a total sediment load of 5.2 km3, with 4.5 km3 of sediment bypassing the channel downslope to a fan or lobe deposit. Estimates of both timing and volume compare well to age-constrained Quaternary submarine channels (e.g., Amazon, Zaire, Niger Y) and illustrate the importance of submarine channels as conveyors of sediment to the deep-ocean sink.
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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 | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.002 |
| 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".